[nato]

Stick with it bud, people follow the mob in this hype filled culture. Do what you do and good things come from it.

P.S. Im damn glad to read smart posts.... Im liking this place more and more!

 

[thaflyinfatman]

Funny I got pretty much the same answer from my friend paul.

thanks for the exelent explanation mister thaflyinfatman


At least in the case of the WB fork, the wall thickness of the fork tubes is the same, actually a little thicker if you count the materials for the treads, in fact i took on of the caps apart last night (sad thing to be doing in new years) to make sure the tread were not deform and the cap came out with out any trouble at all, on the shiver, 888 and Super -T i have no idea of the wall thickness variation since i never got the chance to check.

thanks again for your wise and proper input...

actually since you know how of fisics is so deep, what do you think about the setup...!?!?
specially about my empirial claims of less fork flex do to the extended distances in between the crowns...??

The wall thickness at the lower crown is the critical part (I'm guessing that since you mentioned threads, you were referring to the thickness at the upper crown), because the lower crown is the one that is always under a greater load.

As for what I think of the setup, I'm kind of surprised that you can run such a huge stack height between the crowns and still have enough tyre clearance - that fork must be pretty tall if you run it with a conventional setup? That said, that frame does appear to have quite a short headtube.

Regarding stiffness, yes it will be stiffer torsionally when the crowns are further apart. The primary source of flex in inverted forks is due to the fork uppers twisting (or twisting in) the lower crown (and rotating/twisting the upper crown) so that each leg tries to move further away from parallel with the other leg. For example, if (from the rider's position) the front wheel appears to be twisting to the left, the left fork leg will be pushed backwards and the right leg pushed forwards. The stanchions will rotate slightly in the uppers so that there is still a straight line between the axle clamps (obviously, because the axle is holding it like that), but because the stanchions are not fixed torsionally to anything but each other, they have relatively little bearing on the stiffness. So back to the uppers - the further apart the crowns are, the more leverage the top crown has over the lower crown (and vice versa), to hold the fork leg closer to the axis it's meant to be in. This basically translates to more torsional stiffness.

Lateral (fore/aft) stiffness would also be slightly improved, but I very much doubt that kind of flex is a problem on that specific fork anyway.

 

[vitox]

ha!

cool


seen it done before, it just works thats all.

ive tried a couple of times but never with a combo that didnt either make the clamp grab outside the "allowed" area or the tire clearance too small.

what about using the WB integrated stem and mounting the upper crown upside down?

 

[patineto]

The wall thickness at the lower crown is the critical part (I'm guessing that since you mentioned threads, you were referring to the thickness at the upper crown), because the lower crown is the one that is always under a greater load.

Thanks again mister thaflyinfatman...

I manufacture Motorcycle parts so i'm pretty use to Vernier calipers and guages,in this case I use my mitutoyo "Cylinder bore" guage to measure the internal wall thickness on the tubes all the way to the lower clamps and then compare it with the outside diameter of the forks to find out the tube wall thickness....

so i'm sure everything is fine..

As for what I think of the setup, I'm kind of surprised that you can run such a huge stack height between the crowns and still have enough tyre clearance - that fork must be pretty tall if you run it with a conventional setup? That said, that frame does appear to have quite a short headtube.

Regarding stiffness, yes it will be stiffer torsionally when the crowns are further apart. The primary source of flex in inverted forks is due to the fork uppers twisting (or twisting in) the lower crown (and rotating/twisting the upper crown) so that each leg tries to move further away from parallel with the other leg. For example, if (from the rider's position) the front wheel appears to be twisting to the left, the left fork leg will be pushed backwards and the right leg pushed forwards. The stanchions will rotate slightly in the uppers so that there is still a straight line between the axle clamps (obviously, because the axle is holding it like that), but because the stanchions are not fixed torsionally to anything but each other, they have relatively little bearing on the stiffness. So back to the uppers - the further apart the crowns are, the more leverage the top crown has over the lower crown (and vice versa), to hold the fork leg closer to the axis it's meant to be in. This basically translates to more torsional stiffness.

Lateral (fore/aft) stiffness would also be slightly improved, but I very much doubt that kind of flex is a problem on that specific fork anyway.

sometimes I regreat two things...

One that I became a Industrial designer as oppose to a mecanical Engenier.

second that my lenguage skills are so limited in part do to my dixlexia (handicap in any lenguage, even in Espanol my native lenguage) and part for being a lazzypig and stay away from the writen word since is so dificult for me, but the only way to learn after all...

but one thing is for sure you explain the reasoning behind my aproach in a perfect way


thanks again for your Input and exelent know how and descriptions skills..

 

[patineto]

ha!

what about using the WB integrated stem and mounting the upper crown upside down?

Don Vitox Please refer to answer #40 were I explain my concerns about any type of integrated stems, even after saying that I try the aproach you suggest a few months ago, but ussually the clamping area (specially the mounting bolts) are to close togheter and they collide with the headset and steer tube..

actually just for fun and i'm being working on a "Wide footprint" clamping sistem that will make Any handlebar far stiffer than the current "Acept it" aproach ussing basic geometric and fisical theories

I show you soon..

 

[Kornphlake]

I strongly suggest you check the clearance again, to me it looks like under full compression your tire would be hitting the frame. How did you check for clearance anyway? I always remove the springs from my forks and compress them as far as they should compress just to double check the bounce test.

I've actually thought about doing something like that on my bike too, I've got a short headtube and about an inch and a half of steerer tube above the stem that I've yet to saw off. I think I could fit my stem below the top clamp if I wanted to drop my bar height a half inch or so and then I wouldn't need that honking spacer on top of the upper crown.

As I read your posts I kept thinking that you must not be a native english speaker, dyslexia must make things a whole lot more difficult to communicate on the internet. You've got some determination to do what you do and argue your points over the internet even though it must be pretty tough to do, for that I commend you. If it works for you and makes you faster who cares what works for everyone else, like you say you didn't stay alive this long by doing stupid careless things. If you've got a natural ability to look at something and say it will work or break with a moments glance don't second guess yourself just because it looks unconventional.

 

[dhbuilder]

obviously you're taller than the average d.h. racerboy. i'm 6ft. three with a 36in. inseam and folks bust my chops about the amount of seat post i run, and stem spacers too. it looks like your set up takes alot of load off of the tall steerer tube. that part makes good sense. have you had any issues with the top crown hindering any body movement or crash impact ?bottom line, it's your bike. if people don't like it....

 

[OGRipper]

That said, that frame does appear to have quite a short headtube.

Yeah I was thinking was Kornplake said, you need a short head tube to make it work with most current forks.

Patineto, what is your headtube length anyway?

 

[patineto]

I strongly suggest you check the clearance again, to me it looks like under full compression your tire would be hitting the frame. How did you check for clearance anyway? I always remove the springs from my forks and compress them as far as they should compress just to double check the bounce test.

that is exactlly how it did it...

but for my first attemp (4 months ago) I also measure ussing the O-Ring on the fork leg with the fork fully compress and then extrapolate that data to the crown..

I've actually thought about doing something like that on my bike too, I've got a short headtube and about an inch and a half of steerer tube above the stem that I've yet to saw off. I think I could fit my stem below the top clamp if I wanted to drop my bar height a half inch or so and then I wouldn't need that honking spacer on top of the upper crown.

So what stop you...!?!?
comun sense...

Looks to me like you are a super smart and consiensus fellow, so i'm just wondering why you did not go "All the way"

As I read your posts I kept thinking that you must not be a native english speaker, dyslexia must make things a whole lot more difficult to communicate on the internet. You've got some determination to do what you do and argue your points over the internet even though it must be pretty tough to do, for that I commend you. If it works for you and makes you faster who cares what works for everyone else, like you say you didn't stay alive this long by doing stupid careless things. If you've got a natural ability to look at something and say it will work or break with a moments glance don't second guess yourself just because it looks unconventional.

well even if i spend almost 9 years at school (getting diferent deggres,, not just trying to graduate from one) I never learn how to use a typewriter since the mistakes will be far to many...

I start to use a keyboard (Thanks to the "backspace" and "delete" keys) about 4 years ago and today i can not get enogh of it,,, every posting to me is super painful and I edit it, again and again for "missplace" letters and every time i get a little better, (i does not get any easier, it never will)

well sound like your ingles is not you first language,,,

what is...!?!?

 

[patineto]

Yeah I was thinking was Kornplake said, you need a short head tube to make it work with most current forks.

Totally this will not work (at least not that well) with a really long headtube, but for the short ones, make the fork and the stem far stiffer and torzionally stable.

Patineto, what is your headtube length anyway?

"Real headtube" ....

4 1/8"

total stack...
including a lower king Steelhead and a convensional upper with everything...

5 1/4"

 

[patineto]

obviously you're taller than the average d.h. racerboy. i'm 6ft. three with a 36in. inseam and folks bust my chops about the amount of seat post i run

Thanks for making me feel small for ones...

i'm 6'2'' with short legs (33.5") and long torzo and arms (wierd,, ussually all the extremities ..including neck...feature similar proportions)

I also have a masters in ergonomics, so i'm far to aware of the proper biomecanical settings, plus my knees are not that great after a million skateboard crashes many years ago, so i need to be really careful about leg extension all the time to not hurt them even more..

and stem spacers too. it looks like your set up takes alot of load off of the tall steerer tube. that part makes good sense.

well you hit the nail right on the head...

I was looking for many things including improve rigidity of the stem and torzional improvement in the way the wheel tracks..

i think i acomplish that quite well..

have you had any issues with the top crown hindering any body movement or crash impact ?

nOPe Not at all, not even ones...

maybe i'm just old (43) and to stiff to really push the bike to the point that the clamp becomes a issue...

actually if you really think about it, the clamp at the very top only adds less than a 1/4' of a inch(about 3/16'' actually), but in that compromise also "Rounds" all the edges. making the whole set up far less prone to Hurt you (since nothing really sicks out)

bottom line, it's your bike. if people don't like it....

Is kind of funny in a really Sad kind of way, but i'm being around mecanics for far to long and i'm always concern (Most of the time.. except for a few Maverick's i have the pleasure to work with) in how they have "Safety meetings" every half a hour but even wrost how close minded and "Set on the old ways" some of them are....

Just remenber the "Writh Brothers" (The airplane guys) and what they did for humanity a little more than a century ago.. (even if the germans.."otto lilliental".. were flying Gliders 15 years before) they still were very inovative, problem solvers with a really open mind that let them to discover basic prinsiples that still in use today in modern airplanes..

just be proud of your work and challenge you brain as much as you can..

 

[dhbuilder]

43 ain't old. heck i'm closin in on 49 here real soon. and i honestly don't think i've peaked yet. alot of the "younger" guys i ride with(or in front of) would probably back me up on that. keep rippin you " punk assed kid"

 

[Jm_]

I strongly suggest you check the clearance again

Another good question is;

Are there any bottom-out bumpers in the fork, like the ones in a manitou? You wouldn't normally be able to compress these, but under extreme circumstances (where you wouldn't want to endo) they will.

 

[1soulrider]

The more I learn about you and your work the more respect I have for you.
True innovators are often laughed at and overlooked by the mindless masses. It seems to me that the only real criticism that has come up is that 'it just doesn't look right'.
Keep on tinkering.

 

[vitox]

Another good question is;

Are there any bottom-out bumpers in the fork, like the ones in a manitou? You wouldn't normally be able to compress these, but under extreme circumstances (where you wouldn't want to endo) they will.

there are, actually there are 3 of them, one for topout the other two for bottom out (iirc, its been a long time i peeked inside one of those)

to all those who are concerned with the wall thickness, dont be, those legs are the same on all WB inverted forks and they are straight walled all the way down to the upper bushing placement which is of course pretty far away from where patineto is clamping his lower croen to.

anyway, its not like its that hard to measure tire clearance.

 

[Spokompton]

I'm too lazy to read all the replies.

Here's my $.02

You are putting more stress onto the steer tube at the top of the headtube.

When the top crown is flush with the headset, the forces acting on the steer tube are a sheering force which it can take plenty of. There isn't any room for bending.

With the top crown way up there you are in effect putting more stress on the steer tube because it is no longer a sheering effect. It's now a bending effect.

This is the main reason Turner uses 3d rockers that reduce the the amount of shock mount needed, thus reducing the likelyhood of the mounts bending.

Same effect as having weight put onto a string. While holding a string that's 2 inches long, it is much easier to keep it straight with 2 pounds of weight on it, compared to having 2 feet of string with 2 pounds of weight in the center.

Now the real question is whether or not the steer tube can handle this to a safe degree. Just because it works for you doesn't mean it isn't being stressed to 95% of its limit.

I'm too bad at math to calculate this out right now to find exact values, but the idea remains the same. Having the top crown way up there is clearly putting stresses into the stere tube that were not designed to be there.

 

[vitox]

Don Vitox Please refer to answer #40 were I explain my concerns about any type of integrated stems, even after saying that I try the aproach you suggest a few months ago, but ussually the clamping area (specially the mounting bolts) are to close togheter and they collide with the headset and steer tube..

actually just for fun and i'm being working on a "Wide footprint" clamping sistem that will make Any handlebar far stiffer than the current "Acept it" aproach ussing basic geometric and fisical theories

I show you soon..

hey now i remembered when i set up a fork like that, way back in the 00 i had to set up a disco volante with a boxxer and only had a flat crown so before i got a flat crown for it, i put the tall drop (back then RS had 3 crown heights, that and boxxers came with extra tuning springs) crown on over the stem so i could see how the angles would turn out and at the same time be able to parking lot test it safely while tinkering with the eccentrics, i cant remember it being bothersome for kneee clearance at all.
discos are notorious for short headtubes, also around 4" just like on your bike.

as for your concerns with integrated stems, youre of course right, its a guestion of give and take (like in the monkees song) but in a racing application or especially with inverted forks, it takes away one of the irritation moments you can have after a crash, lining up a fork is a lot easier. that being said, the thomson x4 is so light and pretty it takes away a lot of the benefits you could have with an integrated stem.

i have seen this setup on a few kids bikes at the races here, i guess for lower bar height.
one of them also had springs mounted outside the fork stanchion, which right now got me thinking about what the inner radius of a fox40 spring is?

 

[patineto]

43 ain't old. heck i'm closin in on 49 here real soon. and i honestly don't think i've peaked yet. alot of the "younger" guys i ride with(or in front of) would probably back me up on that. keep rippin you " punk assed kid"

well I quess in my case is not so much about the "Fabrication date" that the High Milliage...

My Bike coach use to tell me something like this many years ago...

"Ricardo be careful.. life is like a Credid card, you spend and spend but sooner or later you are going to end up paying for it and the wrost part is that you never know how much the interest rate is going to be..."

Needless to say I was Overdraft, over spend... and all the other bad stuff from pushing my self a little to hard for far to long..

 

[patineto]

Another good question is;

Are there any bottom-out bumpers in the fork, like the ones in a manitou? You wouldn't normally be able to compress these, but under extreme circumstances (where you wouldn't want to endo) they will.

You Know JM I did not go that far..

maybe I need to take you advice and do a "Full Monty" on Them and really see that i have before i go fubar over the handlebars..

 

[patineto]

The more I learn about you and your work the more respect I have for you.
True innovators are often laughed at and overlooked by the mindless masses. It seems to me that the only real criticism that has come up is that 'it just doesn't look right'.
Keep on tinkering.

Thanks 1soulrider...
is actually not so hard to do, you just need to leave the preconceptions on this side and go for what the laws of fisics tell you, since more humans are far to contaminated with way to many missconceptions..

Go ahead Try it out is not so hard,,, Hell I can not do a "Manual" to safe my life, thinking outside of the box is for sure far less dificult...

 

[patineto]

there are, actually there are 3 of them, one for topout the other two for bottom out (iirc, its been a long time i peeked inside one of those)

to all those who are concerned with the wall thickness, dont be, those legs are the same on all WB inverted forks and they are straight walled all the way down to the upper bushing placement which is of course pretty far away from where patineto is clamping his lower croen to.

anyway, its not like its that hard to measure tire clearance.

Well I guess you safe me from a mess on the carpet..
Do you think they will compress that far to really high the upper crown...!?!?

so Vitox do you have any X-ray fotos of the WB forks...?!?!

actually what i really want will be some tuning advice since i'm not extremlly happy about the way this forks perform...

I see your "tuning" posting before and they are Brilliant, i just wish you made one for a fork I have,,, Maybe you did and i just don't know about it...

 

[patineto]

I'm too lazy to read all the replies.

Here's my $.02

You are putting more stress onto the steer tube at the top of the headtube.

When the top crown is flush with the headset, the forces acting on the steer tube are a sheering force which it can take plenty of. There isn't any room for bending.

With the top crown way up there you are in effect putting more stress on the steer tube because it is no longer a sheering effect. It's now a bending effect.

This is the main reason Turner uses 3d rockers that reduce the the amount of shock mount needed, thus reducing the likelyhood of the mounts bending.

Same effect as having weight put onto a string. While holding a string that's 2 inches long, it is much easier to keep it straight with 2 pounds of weight on it, compared to having 2 feet of string with 2 pounds of weight in the center.

Now the real question is whether or not the steer tube can handle this to a safe degree. Just because it works for you doesn't mean it isn't being stressed to 95% of its limit.

I'm too bad at math to calculate this out right now to find exact values, but the idea remains the same. Having the top crown way up there is clearly putting stresses into the stere tube that were not designed to be there.

Thanks Spokompton sadlly my level of structural undertanding is deep enogh to get my "In Trouble" but not sufficent to keep me away from it...

so far is two diametrally oposite opinions and sincerlly i have no idea who is "more" right...

 

[Spokompton]

Thanks Spokompton sadlly my level of structural undertanding is deep enogh to get my "In Trouble" but not sufficent to keep me away from it...

so far is two diametrally oposite opinions and sincerlly i have no idea who is "more" right...

I agree in that the way you have it will result in more stiffness.

on the flip side, there is no doubt AT ALL that the steer tube is seeing more stress than it would with the crown lower.

THE BIG question is how close to the steerer tube's limit are you getting? Also, how bug do you go? Ride Dh or do large drops?

 

[patineto]

hey now i remembered when i set up a fork like that, way back in the 00 i had to set up a disco volante with a boxxer and only had a flat crown so before i got a flat crown for it, i put the tall drop (back then RS had 3 crown heights, that and boxxers came with extra tuning springs) crown on over the stem so i could see how the angles would turn out and at the same time be able to parking lot test it safely while tinkering with the eccentrics, i cant remember it being bothersome for kneee clearance at all.
discos are notorious for short headtubes, also around 4" just like on your bike.

Funny... Some how a few years ago i discover the possiblities of this set up by mistake when we(Stonnned parts manager) order the wrong clamps for a Boxxer and i end up mounting the clamp on top for the weekend until we got the proper clamp a few days later...

then i remenber about it,
when i try to mount my Scott's damper about 4 month ago..

as for your concerns with integrated stems, youre of course right, its a guestion of give and take (like in the monkees song) but in a racing application or especially with inverted forks, it takes away one of the irritation moments you can have after a crash, lining up a fork is a lot easier. that being said, the thomson x4 is so light and pretty it takes away a lot of the benefits you could have with an integrated stem.

that totally make sense, specially if you are not paying for you own equipment when the sponsor pick up the bill...

In My case I don't race much and for sure I don't get paid to destroy my equipment, but for sure I can understand your argument really well.

For sure You are a "smartlly pant fellow" just the way i like it..

i have seen this setup on a few kids bikes at the races here, i guess for lower bar height.
one of them also had springs mounted outside the fork stanchion, which right now got me thinking about what the inner radius of a fox40 spring is?

Man that must scratch the surface coating of the forks in no time...

keep posting you progress,,,i'm sure will be fun and for sure useful..

 

[vitox]

Well I guess you safe me from a mess on the carpet..
Do you think they will compress that far to really high the upper crown...!?!?

so Vitox do you have any X-ray fotos of the WB forks...?!?!

actually what i really want will be some tuning advice since i'm not extremlly happy about the way this forks perform...

I see your "tuning" posting before and they are Brilliant, i just wish you made one for a fork I have,,, Maybe you did and i just don't know about it...

glad you like the autopsy series posts!

i have some exploded views of white forks, but im not on my work pc so ill post later.

as for your clearance concern, just see to that you have say 185mm of space between the rubber and the crown. that fork is also relatively easy to modify for more travel since wb cartridges always are capable of far more than the spring is.

tuning-wise (i didnt have a digital camera when i used to work the WB´s often so no threads...), if your not happy with the performance i suggest you find out if your fork has metallic or plastic bushings inside, if they are plastic (difference is huge in performance, at least in my experience) you can spot them because they are fairly tall, more than one inch, if they are metallic, check them for even wear (with a flashlight or one of those cool new LED headlamps).
then lube, i used to use slick honey but you can use the more readily available motorex manitou grease, its the honey colored one you want.
you can also lube with oil but that will require good seals and if you have been running the fork dry (no lubrication oil) then chances are your seals will not work, call WB for the seal and possibly bushings because that particular oil seal size is hard to get (32ID and i think 39OD).
the damper on that fork isnt quite as drag free as the one on the piggyback fork though so you might never get the same performance as on the dh3 or 2.0 (possibly my favorite inverted forks of all times) but there are a couple minor things you can do to it too.

 

[patineto]

I agree in that the way you have it will result in more stiffness.

That is for Sure...
the bike responds extremlly well to handlebar imputs and the wheel track almost telepatetically .

on the flip side, there is no doubt AT ALL that the steer tube is seeing more stress than it would with the crown lower.

THE BIG question is how close to the steerer tube's limit are you getting?

I need to wait until my Mega Metalurgical Geeks friends come back from vacation and back to work at the berkeley and livermore Labs to ask them about the posible loads and failures..

for sure I Undertand you concern about sheering loads, on the good side the steer tube being aluminum (not so good i know) features about 3mm of wall thickness..

Also, how bug do you go? Ride Dh or do large drops?

Drops... Nothing More that 6"/8" feet high .
fast i did race at mamoth on a hardtail two times (94' and 95') and i reach almost 48mph,, so i'm not that slow, plus i grow up in the full rigid days, so i'm used to float over things really wellas oppose to high them really hard.

 

[patineto]

glad you like the autopsy series posts!

i have some exploded views of white forks, but im not on my work pc so ill post later.

as for your clearance concern, just see to that you have say 185mm of space between the rubber and the crown. that fork is also relatively easy to modify for more travel since wb cartridges always are capable of far more than the spring is.

tuning-wise (i didnt have a digital camera when i used to work the WB´s often so no threads...), if your not happy with the performance i suggest you find out if your fork has metallic or plastic bushings inside, if they are plastic (difference is huge in performance, at least in my experience) you can spot them because they are fairly tall, more than one inch, if they are metallic, check them for even wear (with a flashlight or one of those cool new LED headlamps).
then lube, i used to use slick honey but you can use the more readily available motorex manitou grease, its the honey colored one you want.
you can also lube with oil but that will require good seals and if you have been running the fork dry (no lubrication oil) then chances are your seals will not work, call WB for the seal and possibly bushings because that particular oil seal size is hard to get (32ID and i think 39OD).
the damper on that fork isnt quite as drag free as the one on the piggyback fork though so you might never get the same performance as on the dh3 or 2.0 (possibly my favorite inverted forks of all times) but there are a couple minor things you can do to it too.

Man Vitox even You S^^t smells like french perfume....

what a great Posting,,,

I think i need to read it a few times to really understand it at full deep, but so far I can tell you i have the delrin (plastic) bushing and that the fork bushings are for sure really dry...

i get back to you when i asimilate your posting a little better..

 

[Kornphlake]

that is exactlly how it did it...

but for my first attemp (4 months ago) I also measure ussing the O-Ring on the fork leg with the fork fully compress and then extrapolate that data to the crown..

Well I guess it's just the camera that makes it look like the tire would collide with the down tube. You're a smart enough guy to know if there's really enough clearance or not, but from time to time we get guys who really don't have enough common sense to think that if they can't get the tire to rub somewhere by bouncing on the fork it'll be okay. "Double check" is my standard warning.

So what stop you...!?!?
comun sense...

Looks to me like you are a super smart and consiensus fellow, so i'm just wondering why you did not go "All the way"

I really don't feel like there's any reason to get my handlebars any lower than they already are. Otherwise I'd be game to do what you've done. Who cares what my bike looks like as long as I can keep up on rides.

well even if i spend almost 9 years at school (getting diferent deggres,, not just trying to graduate from one) I never learn how to use a typewriter since the mistakes will be far to many...

I start to use a keyboard (Thanks to the "backspace" and "delete" keys) about 4 years ago and today i can not get enogh of it,,, every posting to me is super painful and I edit it, again and again for "missplace" letters and every time i get a little better, (i does not get any easier, it never will)

well sound like your ingles is not you first language,,,

what is...!?!?

Ingles is my first language but I'm fluent in espanol as a second language. I learned spanish through conversation more than anything else, I'm super self concious about written spanish though, as I know that what I write isn't even close to gramatically correct. I only had about 2 months of formal Spanish classes outside of high school so I don't really know all the rules of the written language, when people ask I tell them I speak Mexican Ghetto Spanish. Heck, I'm not even sure of all the gramatical nuances of the English language and I've been speaking it for quite a while and I've had well over a decade of written English courses.

 

[patineto]

Well I guess it's just the camera that makes it look like the tire would collide with the down tube. You're a smart enough guy to know if there's really enough clearance or not, but from time to time we get guys who really don't have enough common sense to think that if they can't get the tire to rub somewhere by bouncing on the fork it'll be okay. "Double check" is my standard warning.

actually maybe I Overlook something...

I did all the Measurement for this fork on my First (and favorite) Balfa FR that have a totally "Flat" Down tube.

But your Comment about the tyre highing the DOWNTUBE got me thinking and you are right,, the downtube on the balfa HD is somehow Bend at the end making for a lower downtube profile as you can see on the picture..

I just Check really fast and I think i still a have about 3/4" of a inch but i'm going to go deeper and take the springs out before i ride it again...

Another thing i learn over the years is that....
Being Stubborn can also get you Kill and that is much easier to acept you make a mistake and for sure I confess I Totally overlook the downtube clearance on the new HD,,, assuming that they were the same as the old FR...

for sure Thanks for the heads up...

I really don't feel like there's any reason to get my handlebars any lower than they already are. Otherwise I'd be game to do what you've done. Who cares what my bike looks like as long as I can keep up on rides.

Sure I don't claim this set up is the cure for everything,, is just a alterative with some benefits and i'm sure some short comings

Ingles is my first language but I'm fluent in espanol as a second language. I learned spanish through conversation more than anything else, I'm super self concious about written spanish though, as I know that what I write isn't even close to gramatically correct. I only had about 2 months of formal Spanish classes outside of high school so I don't really know all the rules of the written language, when people ask I tell them I speak Mexican Ghetto Spanish. Heck, I'm not even sure of all the gramatical nuances of the English language and I've been speaking it for quite a while and I've had well over a decade of written English courses.

some people have it, some don't..

on of my best girlfriends learn 5 other diferent languages, some of them like italian in a two month vacation,, the funny part was that she sound more italian that even the iTalian, same with german, french...

Man she was so sexy , i miss her so much..


actually i was born in New york but we move to sur america when i was 18 months old, to never return (expet for one vacation) until 1994..
I did take a million ingles classes but I always suck at them, the thing that got me to learn Ingles were the Skateboard magazines that i want to read so bad, and years later bicycle and motorcycle and a bunch of books about composites, engenierring and design

for a long time I understand the spoken ingles pretty well, specially on movies were the tempo is kind of slow and the pronunciation proper, reading takes time but i can do it...

Typing...oh well..

we are Fonetical... like in Spanish the words are spell exactlly as they sound,, in inlges half of them are "VIsuaL" like in i need to write them,, then look at them and see if they look right (Half the time I have no idea what is wrong with them until i try a few permutations) and the word like "Just Right"

oh well I keep trying, maybe some day i will also learn about the proper gramatic structures,,
to me that is a total mistery and almost blackmagic

 

[patineto]

Okay I just check the downtubes and everything is fine...

was all a "Optical Ilussion"
as you can see the Lower pivot point on the FR, is far forward and also lower than the botom bracket, making for a straight tube, that pretty much have the same measurements as the HD

Look at the Location of the lower VPP mount on the HD,, above the bottom bracket shell.

anyway i got lucky this time nothing was wrong, but I need to admite I overlook the downtube issue (assume they were the same) and at the end we all know they are only Two rules that always aply the laws of fisics but also the sad, sinister and persistent Murphy's law...

 

[dhbuilder]

well I quess in my case is not so much about the "Fabrication date" that the High Milliage...

My Bike coach use to tell me something like this many years ago...

"Ricardo be careful.. life is like a Credid card, you spend and spend but sooner or later you are going to end up paying for it and the wrost part is that you never know how much the interest rate is going to be..."

Needless to say I was Overdraft, over spend... and all the other bad stuff from pushing my self a little to hard for far to long..

although the english is rather broken, all the above statements are very well put.
old guys are still gettin it done.

 

[Biscuit]

I've wondered about this before, it would make the fork much stiffer for the same reasons a dual crown is stiffer than a single crown.

My concerns:
1) Making sure the fork isn't internally butted, which you already addressed.
2) Making sure the crown didn't hit the seals on an non-inverted fork, which you already addressed.
3) Hitting my knees on the crown, which I think is more painfull than falling.
4) I'm trying to think if that would put more stress on the headtube, but I'm still recovering from new years and don't want to think.
5) There is potential for the front wheel to hit your downtube when fully compressed. Which would be bad. But a lot of forks are way too long as it is, so you might be okay there.
6) Your english is getting much better Patineto.

*edit: apparently no. 5 has also been addressed. 5 pages is too much reading for me.

 

[vitox]

Man Vitox even You S^^t smells like french perfume....

what a great Posting,,,

I think i need to read it a few times to really understand it at full deep, but so far I can tell you i have the delrin (plastic) bushing and that the fork bushings are for sure really dry...

i get back to you when i asimilate your posting a little better..

thanks for the compliment but i totally disagree! (my old housemates too)

if you have the plastic bushings then youd do yourself a favor by replacing them as quick as possibe, they are just not up to par with the rest of the fork.
go to www.ekosport.com and call them up about a bushing/seal kit for a dh fork, i think the part number is 873x, careful so you dont get any plastic bushings again.
btw the metal bushing is the same you find in RS boxxer pre 2005 upper bushings. the newer forks use 4 per side but you dont need more than 2 or 3.
post when you get them, that way we´ll have another post in the autopsy series, removing and installing bushings on these and most other inverted forks is really easy.

 

[patineto]

thanks for the compliment but i totally disagree! (my old housemates too)

well I don't even have Roommates for that exact same reason...

if you have the plastic bushings then youd do yourself a favor by replacing them as quick as possibe, they are just not up to par with the rest of the fork.
go to www.ekosport.com and call them up about a bushing/seal kit for a dh fork, i think the part number is 873x, careful so you dont get any plastic bushings again.
btw the metal bushing is the same you find in RS boxxer pre 2005 upper bushings. the newer forks use 4 per side but you dont need more than 2 or 3.
post when you get them, that way we´ll have another post in the autopsy series, removing and installing bushings on these and most other inverted forks is really easy.

Exelent,,
i will call them tomorrow...

I replace many seals, Bushings and valves over the years on bicycles and motorcycles, i have absolutlly no fear about performing this operation...

gracias Amigo..

 

[NORTON]

oh if you are ever around berkeley (near san francisco) just bring your shoes , gloves and helmet, since i have a whole stable of bikes you can ride, including a nice tandem a bunch of single speeds and corss country bikes plus two balfas and hopefully soon two Nicolai's .

If I'm ever in the area I will definately look you up! You have so much passion for bikes in all your threads I'll bet you are a lot of fun to ride with I extend the same offer to you if you are ever in Colorado, I just don't have so many cool bikes

Yeah you are understanding wrong. The couple moment exerted on the HEADTUBE (for a given/fixed headtube length) is a function of the distance from the axle to the top headset cup. As you can imagine, running the fork up that high relative to the headtube actually shortens the distance from axle to upper headset cup, thus reducing the load on the headtube. Having such widely spaced crowns means that the load on each crown is reduced too. However, if the crowns are placed in a region of the tube that is thinner than the area intended to be clamped, you greatly increase the risk of damaging the tube.

Well I'm still no engineer but you seem to assume that the only input of force comes from the wheel. That's mostly true but I think it works in both directions. You can change it to- "The couple moment exerted on the HEADTUBE (for a given/fixed headtube length) is a function of the distance from the handlebar/stem/top crown interface to the bottom headset cup. " and it still makes sense.

Jump off a cliff and you sink an awful lot of force into the bars, at least I do with my craptastic landings, regardless how much the fork absorbs. Not as much as comes from the wheel/fork lever, of course, but still there. Or not. But it sure looks like it to me! Hmm--- the force acts on the same area as the wheel/fork lever (headtube), and the handlebar/stem/top crown area is so much shorter than the fork (less leverage), that even if I am 100% correct, there is zero danger of failure. And if I'm wrong, it doesn't matter at all! Cool!

 

[patineto]

If I'm ever in the area I will definately look you up! You have so much passion for bikes in all your threads I'll bet you are a lot of fun to ride with I extend the same offer to you if you are ever in Colorado, I just don't have so many cool bikes

thanks...

the amount of bikes does not matter is the spirit what really counts...

actually i'm being in Colorado at least ones a year for the last 3 years,,, I love the mountains and the people too...

Well I'm still no engineer but you seem to assume that the only input of force comes from the wheel. That's mostly true but I think it works in both directions. You can change it to- "The couple moment exerted on the HEADTUBE (for a given/fixed headtube length) is a function of the distance from the handlebar/stem/top crown interface to the bottom headset cup. " and it still makes sense.

Jump off a cliff and you sink an awful lot of force into the bars, at least I do with my craptastic landings, regardless how much the fork absorbs. Not as much as comes from the wheel/fork lever, of course, but still there. Or not. But it sure looks like it to me! Hmm--- the force acts on the same area as the wheel/fork lever (headtube), and the handlebar/stem/top crown area is so much shorter than the fork (less leverage), that even if I am 100% correct, there is zero danger of failure. And if I'm wrong, it doesn't matter at all! Cool!

Actually I make Motorcycle handlebars mounts for a living as part of my Company ergononimic services, so i'm well aware of the forces that you encounter

stuff like this

or like this.

and i also have a nice Group of really happy campers as client and friends..

one more reason to get my prototype of the "Wide mount" sistem made so i show you a Bicycle Bar mount "Ricky Style"...

 

[thaflyinfatman]

I'm too lazy to read all the replies.

Here's my $.02

You are putting more stress onto the steer tube at the top of the headtube.

When the top crown is flush with the headset, the forces acting on the steer tube are a sheering force which it can take plenty of. There isn't any room for bending.

With the top crown way up there you are in effect putting more stress on the steer tube because it is no longer a sheering effect. It's now a bending effect.

This is the main reason Turner uses 3d rockers that reduce the the amount of shock mount needed, thus reducing the likelyhood of the mounts bending.

Same effect as having weight put onto a string. While holding a string that's 2 inches long, it is much easier to keep it straight with 2 pounds of weight on it, compared to having 2 feet of string with 2 pounds of weight in the center.

Now the real question is whether or not the steer tube can handle this to a safe degree. Just because it works for you doesn't mean it isn't being stressed to 95% of its limit.

I'm too bad at math to calculate this out right now to find exact values, but the idea remains the same. Having the top crown way up there is clearly putting stresses into the stere tube that were not designed to be there.

The polar moment of inertia of a steerer tube is relatively large compared to say a handlebar or similar. You're right in saying the top of the steerer will now be under a bending load, however, single crown forks put ALL the bending load that the fork has to deal with on the steerer tube (whereas even in this case, the pair of shear forces can generate a very large couple moment). I'd be EXTREMELY surprised (as in, on the scale of "Why didn't the sun come up this morning?") if the top of the steerer tube failed because of this.

 

[thaflyinfatman]

Well I'm still no engineer but you seem to assume that the only input of force comes from the wheel. That's mostly true but I think it works in both directions. You can change it to- "The couple moment exerted on the HEADTUBE (for a given/fixed headtube length) is a function of the distance from the handlebar/stem/top crown interface to the bottom headset cup. " and it still makes sense.

Jump off a cliff and you sink an awful lot of force into the bars, at least I do with my craptastic landings, regardless how much the fork absorbs. Not as much as comes from the wheel/fork lever, of course, but still there. Or not. But it sure looks like it to me! Hmm--- the force acts on the same area as the wheel/fork lever (headtube), and the handlebar/stem/top crown area is so much shorter than the fork (less leverage), that even if I am 100% correct, there is zero danger of failure. And if I'm wrong, it doesn't matter at all! Cool!

I can see where you're coming from, but I think you may be missing a bit of information here. If you analyse the system by just using force on the axle and the subsequent moment it places on the headtube, you can do it very simply (as I outlined above). This is because you know that force on the axle is going to be vertical (or close to) all the time, so you know the force vectors and the moment arm(s) that apply. However, if you start with the handlebars, you need to know exactly which direction your hands push in when you land... and you also need to know the reaction force vectors at the bottom bracket (because that's obviously affixed to the headtube by means of the front triangle, so the force at your feet also has an effect on the loads on the headtube) and the rear wheel etc. Whilst this is definitely possible, it's much more complex and likely to be inaccurate IMO.

But yes like you say, either way it's highly unlikely to be dangerous.

 

[patineto]

The polar moment of inertia of a steerer tube is relatively large compared to say a handlebar or similar. You're right in saying the top of the steerer will now be under a bending load, however, single crown forks put ALL the bending load that the fork has to deal with on the steerer tube (whereas even in this case, the pair of shear forces can generate a very large couple moment). I'd be EXTREMELY surprised (as in, on the scale of "Why didn't the sun come up this morning?") if the top of the steerer tube failed because of this.

Man mister Flying FatDude...

you are really good at this stuff...

your argument about the single crown pretty much solve the whole puzzle...

thanks again for your exelent Imput..

 

[patineto]

So far i have 3 bikes running the same setup and loving it, hopefully soon i will get a longer steer collumn for a DC shiver I have to install on my Nicolai and then will be four (Anybody know if the make upper drop {not flat but gulfwing} crowns for the shivers...!?!?)

this one is my friend david's bike that i'm building for him just the way i like it..

here is the new member of the team, a awesome 2001 balfa BB7 (Notice the inwards linkage plates).

the BB7 bottom bracket is so high the drop crowns on the 888 work kind of okay, at least a lot less rake front end than ussual.

as ussual I improvise a few little solutions, including a way to keep the cables from rubbing on the frame but at the same time to keep them free to move as much as they need..

first I wrap some electric tape to the frame (helps the frame is black) then I place a pair of zipties about One inch apart, this help secure another ziptie with a Loop that provides a nice and unrestricted range of motion for the wires,,, as ussual if I saw the problem before I install the cables on the bike I may go even fancier ussing some O-ring or something with out adjustments like a ziptie,,oh well is always next time..