that is wrong, pure and simple. The top crown supports the lower crown through the sliders in all moment directions, this is the key you are missing. I don't understand why you arent seeing this simple fact.Cave Dweller said:
Long Travel RS SC from Tapei
- Thread starter OGRipper
- Start date
I'm sticking another crown over my stem "a la patineto" for the first ever in the history of ever triple crown. I might even stick one just above the sliders. I might lose some travel but boyoboyoboy is it gonna be stiff.zedro said:
Sweet, that would be so burly you could probably lose a whole leg that way...a "pennytech" lefty...kidwoo said:
german BIKE magazin tested the first boxxer ride vs sherman breakout plus
torsional stiffness 20,3 / 29,6
braking stiffness 189,9 / 284,1
(Nm/°)
torsional stiffness 20,3 / 29,6
braking stiffness 189,9 / 284,1
(Nm/°)
My next fork is going to be nothing but crowns.kidwoo said:
I wear a crown when I play halo.Just James said:
For dumb people like me I like to think in simple terms.zedro said:
Single crown: If I hold a garden shovel with both hands grasping next to each other a foot from the end of the handle and have some one push on the blade I have to fight hard to keep it from moving.
Dual Crown: Now move your hand closest to the end of the handle out (so your hands are roughly a foot apart) and have a friend push down on blade again. It takes consideralbly less effort to steady and maintain the blades position.
With comparable clamping area (two hands) the Dual Crown example will be much stiffer at the crown. How much? Don't know, don't care.
Is it enough to change anyones opinion here? Again...don't know, don't care.
How does 1.5 fit into this? Maybe it is giving the guy holding the shovel bigger forearms to hold the single crown?
not dumb at all....gotta know your audience thoRhinofromWA said:
Notice that as RS forks finally get internals that actually work and compare well to the competition, you hear less and less from me.
Looks like they're going to have an excellent lineup next year, I'd say the boxxer needs bigger stanchions to compete with the other companies at 8" of travel, but other than that they are looking pretty decent.
Looks like they're going to have an excellent lineup next year, I'd say the boxxer needs bigger stanchions to compete with the other companies at 8" of travel, but other than that they are looking pretty decent.
You weren't my audience *kiss-kiss*zedro said:not dumb at all....gotta know your audience tho
It was for the other yahoo's (like me)
i know :redX:RhinofromWA said:You weren't my audience *kiss-kiss*
It was for the other yahoo's (like me)
You have mis quoted me.zedro said:
What i said is the top crowns function in a pure fore and aft motion is to just provide a spot to apply a reaction force.
If im incorrect then so is every bridge that has ever been built. So, in a bridge are you saying the supports add to the stiffness of the bridge, or is it due to the thickness / construction of the beam spanning the supports that makes the differance?
Think about it, if the leg was made of spaghetti having a chunky crown will make freak all difference. The extra stiffness is from the section of leg between the upper and lower crown, as long as the top crown can take the reaction force every thing is sweet.
In a twisting/deflection motion it is more of a case of the legs twisting along its axis, therefore surface area of contact is very important to try and resist this twisting motion.
So, are you saying it is not possible AT ALL to make a single crown as stiff as a tripple clamp?. I can guarantee that a breakout is stiffer then a huffy triple crown.
It comes down to how well it is engineered and SRAM seem to be on the ball. I will bet good money that that fork will be stiff as, care to take me up on that?
They look to be 1_1/8
If it is as stiff as you're expecting,won't that stiffness therefore take a bigger toll on the headset,frame and possibly bushes without a top crown to dissipet/take some of the load?Hense my statement about maybee it would be better with 32mm stanchions so they have some give(not for feel wich ultimatelly is more important).Possibly 1.5 will give the headset more strength but then won't the frames take more abuse,sorta passing the buck to the frame builders but I guess thats ok,just will mean yeah the fork weight might be similer to tripples but frame weights will increase.
Whats the bet? How many beers and what two forks are we comparing?I will not bet against any 32mm tripple as I think they're flexy.
I think 66 vs 888 is the most even comparison and your witnessing bent steerers or whatever should ad to my above statement/question.
Or maybee the new Travis,they do them in both do they not?
Whats the bet? How many beers and what two forks are we comparing?I will not bet against any 32mm tripple as I think they're flexy.
I think 66 vs 888 is the most even comparison and your witnessing bent steerers or whatever should ad to my above statement/question.
Or maybee the new Travis,they do them in both do they not?
you're assumption is that the reaction force is applied at a single point on the fork tube from the crown, when reality it's applied at multiple points and at various magnitudes.Cave Dweller said:
also, the reaction to reducing twisting is coming from friction between the fork tubes and the crown. friction IS a function of normal force and the coefficient of friction between the two surfaces. it is NOT a function of surface area.
i dont even know what anyone is arguing about anymore, but it's fun. i like being a nerd. almost as much as i like riding my bike
all the protos that have been around have been 1 1/8th
not sure if that means production ones will be, but i would expect that. those pics look like 1 1/8 to me too.
not sure if that means production ones will be, but i would expect that. those pics look like 1 1/8 to me too.
Curtis put down your design book, put down the bong and go finish your senior project. God knows we need more pedals out there without bearings. Haha, just kidding bro...I like to see you learned something in streangths.beaverbiker said:you're assumption is that the reaction force is applied at a single point on the fork tube from the crown, when reality it's applied at multiple points and at various magnitudes.
also, the reaction to reducing twisting is coming from friction between the fork tubes and the crown. friction IS a function of normal force and the coefficient of friction between the two surfaces. it is NOT a function of surface area.
i dont even know what anyone is arguing about anymore, but it's fun. i like being a nerd. almost as much as i like riding my bike
But I'd be willing to bet that a duel crown 40mm stanchion fork is stiffer than that single crown. You have to compare apples to apples.Cave Dweller said:
That being said I've ridden a Sherman breakout and a slider on identicaly prepared ASX's and the slider was stiffer. That was as close to apples to apples as it's going to get. The difference isn't going to matter to most people, but it's there.
i never said that, does it seem like i'd make such a silly claim? All i was arguing is that you were ignoring a few force components which reveal how dual crowns stiffen up a fork for a given chassis; you are oversimplifying the actual force model. The lower crown wants to twist along the same axis direction as your hub; that force moment (torque) will cause a fore-aft flex. Using a second crown bridged with stanchions will help prevent it from twisting along that axis (among others). A single crown is simply unsupported in this respect, and even doubling its size will still not achieve the same results as having a dual crown at half the size.Cave Dweller said:
Don't start arguing that a DC SID isnt gonna be as stiff as an SC 36 to prove a point cus i'll have to come over there and slap ya!
I rarely post but since no one has said anything yet......
Looks like there are new internals in the Totem. Note the new sticker on the crown. Not the same Motion Control one. I know the little blurb says they will be launching the Mission Control damping sytem next year but they make it sound like a lower-end version of Motion Control. Maybe it's just their name for the BoXXer version of MC where the floddgate acts as a high speed compression adjust rather than a lockout.
The fork will also be coming in 1 1/8 as well as 1.5.
There was a vid of it in action a while back on the Blck Box site.
Looks like there are new internals in the Totem. Note the new sticker on the crown. Not the same Motion Control one. I know the little blurb says they will be launching the Mission Control damping sytem next year but they make it sound like a lower-end version of Motion Control. Maybe it's just their name for the BoXXer version of MC where the floddgate acts as a high speed compression adjust rather than a lockout.
The fork will also be coming in 1 1/8 as well as 1.5.
There was a vid of it in action a while back on the Blck Box site.
Ahhhmmmm....... no. You can't assume this is a box sliding on the ground with you typical straight line F=ma stuff. You are talking a rotational motion.beaverbiker said:
Think about it logically. Are you saying that it would take the same amount of torque to rotate a leg in a crown 1cm thick as one that is 1km thick?? Don't think so champ.
If you read all my posts you would have seen i already said that.maxyedor said:
Zedro, of course i am simplifying!zedro said:
Something as "simple" as a suspension fork is both a static and a dynamic system. There is no way you could model the problem in every loading situation it will encounter during its life time. And we haven't even delved into the dynamics of the fork, it would have multiple degrees of freedom that would no doubt be highly non linear and would also have multiple natural frequencies, damping and mode shapes that would effect the strength of the fork.
If you don't make simplifications you would never be able to model it. There is no way you could model that fork either statically or dynamically without simplifying the problem, well, maybe if you had access to the NASA super computers and you had a hell of a lot of time on your hands. I work on multiple degree of freedom non-linear vibration problems daily, you have to simplify if you want to ever get any results.
That, my friend, sounds like a "plucked from thin air" assumption, do you have the calculations to back that upzedro said:
Don't forget a box section that is twice as thick and twice as wide is fours times as stiff.......
actually basic force and beam equations and a basic understanding of mechanics without crunching numbers will tell you so since everythings relative. Whats stronger/stiffer, an I-beam (ie. DC) or the equivalent flat bar without the I part (ie. SC). An I-beam is nothing more than an efficient really big flat-bar with the fat removed....Cave Dweller said:That, my friend, sounds like a "plucked from thin air" assumption, do you have the calculations to back that up
anyways enough of this...
As far as the stiffness issues go, either design can be made stiff enough, and determining which is stiffer per gram is just splitting hairs.
But back on topic, here's some info I saw over at MTBR about what's in store for 2007 from RS. There are two new technologies, an expanded motion control damping system called mission control, and a new rapid travel reduction system called 2-Step. None of this stuff below is confirmed as far as I know.
I'd love a coil 2-Step Lyric for my prophet, in silver.
The dirt:
Pics:
Totem:
Domain:
But back on topic, here's some info I saw over at MTBR about what's in store for 2007 from RS. There are two new technologies, an expanded motion control damping system called mission control, and a new rapid travel reduction system called 2-Step. None of this stuff below is confirmed as far as I know.
I'd love a coil 2-Step Lyric for my prophet, in silver.
The dirt:
- Mission Control Damping: Rebound, high and low speed compression, floodgate/lockout.
- 2-Step Travel Adjust: rapid 45mm travel reduction.
- High-end single crown
- 40mm stanchion
- 180 or 135-180mm travel
- 1 1/8 or 1.5 aluminum steerer
- 2-step/Solo air/Fixed coil
- Mission Control
- Maxle
- High-end single crown
- 35mm stanchion
- 160 or 135-160mm travel
- 1 1/8 or 1.5 aluminum steerer
- 2-step/Solo air/U-Turn
- Mission Control
- Maxle
- Budget single crown
- 35mm stanchion
- 180 or 135-180mm travel
- 1 1/8 or 1.5 aluminum steerer
- 2-step/Solo air/Fixed coil
- Motion Control
- Maxle
- Budget single crown
- 32mm stanchion
- 100mm travel
- 1 1/8 steerer (probably steel)
- Solo air/Fixed coil
- Motion Control
- Maxle
Pics:
Totem:
Domain:
Ok, time to stop and read all the posts:
Someone posted test results of the Boxxer ride vs. the Breakout plus. These agree with my real world tests - Bkout + and '03 Super T - on my 7 Point. I'm no little guy (190lbs) and I raced both forks. I could not tell an increase in stiffness by switching to the Super T, as most dc proponents would have you believe. Also, if you're running a 1.5" headset, you've increased the bearing size and surface area dramatically. In my experience, there is no resulting decrease in frame/ headset life.
But don't let me stop you from trying to bludgeon each other with elementary physics...
Someone posted test results of the Boxxer ride vs. the Breakout plus. These agree with my real world tests - Bkout + and '03 Super T - on my 7 Point. I'm no little guy (190lbs) and I raced both forks. I could not tell an increase in stiffness by switching to the Super T, as most dc proponents would have you believe. Also, if you're running a 1.5" headset, you've increased the bearing size and surface area dramatically. In my experience, there is no resulting decrease in frame/ headset life.
But don't let me stop you from trying to bludgeon each other with elementary physics...
Hah! You're both failing to understand the difference between static and kinetic friction... and unfortunately surface area does matter in this, static, situation.Cave Dweller said:
You're also failing to catch the difference between force and torque. Ignoring the static vs. kinetic part, Beaver is actually right, because he used the term "force." Who knows if he understand why...
Also, because it's static, that is the two surfaces are static in relation to each other, friction really has nothing with the stiffness of the system. Focus purely on the stress/strain of the sections in your analysis.
Oh, how I miss these discussions. Y'all keep on keepin' on.
good find there john. personnally i will just stick with the pike i just ordered. its going to be much lighter than the forks presented above.
good find there john. personnally i will just stick with the pike i just ordered. its going to be much lighter than the forks presented above.
Good discussion here. I miss reading these type of post. I have been too busy at work to keep up with this thread. Engineering bicycle parts is so much more fun that auto parts. Too bad the auto industry pays 3-4 times what the bike industry does.ohio said:
Next topic: what shorts have the best support. No post allowed without at least a free body diagram.
i prefer a zero-force system myselfChrisKring said:Next topic: what shorts have the best support. No post allowed without at least a free body diagram.
I rode my 2006 Boxxer Team for the first time on Sunday. All I can say is it is a huge improvement over even the 2005 WC I rode last year. Right out of the box the 2006 was preforming noticably better on high speed low amplitude hits than any bicycle fork I have ever used. My 2003 and 2005 WC forks were set up but the 2006 was better before I even started to turn the knobs. I especially liked that I could tune the compression while riding. I really need a way to tune the bicycle suspension like I do on my MX bike where I hit the same whoop section repeatedly while stopping and turning the clickers.Jm_ said:
Truth indeed: the ladies can't get enough of the engineering steeze:ohio said:
We're used to all nighters, we know all about heat transfer, we do it with more torque, engineering couples have better moments, we know how to manage stress and strain, we know how to use rigid cantilevers, 'Lubrication, friction, and wear,' is a class, and we design and build large erections
haha that is funny john. but also so true at the same time. these rules only apply to engineers that are in the major catagories though. i.e. not C.S. and C.E.'s
i hadn't really thought of it that way. that sounds like the reason for the clamping design on the Bos inverted fork.beaverbiker said:
also. in my experience, the majority of flex in a fork is in the stanchions and bushing slop anyway, so i think you guys are arguing about something that doesn't really come into it.
Though there is some deflection in an undersized steerer. I'd say apples to apples would be two forks that weigh the same, the sc with a 1.5 and the dc with a 1.125.
Though there is some deflection in an undersized steerer. I'd say apples to apples would be two forks that weigh the same, the sc with a 1.5 and the dc with a 1.125.
Its Todds new free ride bike - he has just moved to Canada and now wears only Sombrio and no pads.