[buildyourown]

I posted in the BMW porn thread about making Ti floating brake arms. The response was overwhelming. I am going to order a large quantity of tubing and make a run of them. These will be 3/4" in dia, with press fit alum ends. I know this design works, I have had it on my own bike for over a year.
I can make them to custom lengths with whatever size thread you need.
Price is set at a tentative $75. This may change based on tubing price/availability.

FYI, these are lighter than you can imagine when compared side by side to solid aluminum ones.

Anybody interested, who hasn't already contacted me, send me a PM.

 

[vitox]

cool, i dont need one but i think this kind of posts rock!

best of luck to you

 

[ThePriceSeliger]

i might be. can u make em to fit a gemini DH

 

[nickaziz]

how much weight will it save on a racelink?

 

[buildyourown]

i might be. can u make em to fit a gemini DH

NO,
Sorry I should have been more clear. This design will only work as a replacement for rods that have threaded ball joints. Also known as heim joints for you race car guys. The brake therapy is a good example of this design. Also, the brake must be designed so that the rod is in compression, not tension like on the gemini. Because the aluminum ends are pressed/bonded in, I wouldn't trust them in tension.

 

[dropmachine]

Would it work with the 9.5's floater?

 

[buildyourown]

how much weight will it save on a racelink?

don't know the dims of the racelink. But, a 18" long piece of 5/8" solid aluminum weighs 244g. An 18" long piece of 3/4 Ti tube weights 106g.
Do your own math

 

[dw]

I know 6061 T6 Tubing with welded ends is usd for the Yakuza Kumicho (Iron Horse) that floater rod is damn light as is. Do a lot of makers use solid 6061 rod? Seems counter intuative, you know what I mean? Good ol' Euler buckling equations..

Sounds like your part will be quite bling-tastic!

Dave

 

[buildyourown]

I know 6061 T6 Tubing with welded ends is usd for the Yakuza Kumicho (Iron Horse) that floater rod is damn light as is. Do a lot of makers use solid 6061 rod? Seems counter intuative, you know what I mean? Good ol' Euler buckling equations..

Sounds like your part will be quite bling-tastic!

Dave

Welding the tube ends is expensive so a lot of them are solid. The first ones I made where. I know the brake therapy ones are. I think the BMW are tubular 4130.
I think the V10 is tubular aluminum. So is the gemini's

 

[zedro]

I know 6061 T6 Tubing with welded ends is usd for the Yakuza Kumicho (Iron Horse) that floater rod is damn light as is. Do a lot of makers use solid 6061 rod? Seems counter intuative, you know what I mean? Good ol' Euler buckling equations..

Sounds like your part will be quite bling-tastic!

Dave

yeah i dont quite get it either. And wouldnt CF rods be even cheaper than Ti?

i used a ski pole for my mock-up...now that thing was stupid light...and equivalent Ti one would of been heavier.

 

[Fulton]

We're using solid aluminum rods on our bikes, that have been turned down to 12mm in the center, and about 18 mm at the ends. The rods are in tension, and hang below the chainstay. We used some larger diameter hollow rods originally, but they get pretty banged up, and hollow rods don't stand up to near the abuse that a solid one does.

Also, our solids rods, 15.5" long, minus the hem joints, are only 109 grams, and extremely durable.

 

[buildyourown]

Man, everybody is a critic.
Ti is quite a bit cheaper than carbon, and easier to work with. Especially for me cause I'm a metal guy.
Rods above the chainstay rarely get hit. I made a 1/2" dia solid alum rod for my super8 and it was borderline too flexy. That is a long application though.

 

[Sverre]

Superb job buildyourown.

The stock Bmw rods are made of 4130, and weighs 143g. (485mm. long. 19,1").

I'm looking forward to put my girlfriend on a diet

S

 

[buildyourown]

Sverre,
What size tubing it yours? I made mine from 5/8 tubing but it was short. I assumed 3/4" dia for the longer (18-19") ones would be a good choice.
Going with 5/8" would bring the weight down to 80g for a 18" length.

 

[Fulton]

Man, everybody is a critic.
Ti is quite a bit cheaper than carbon, and easier to work with. Especially for me cause I'm a metal guy.
Rods above the chainstay rarely get hit. I made a 1/2" dia solid alum rod for my super8 and it was borderline too flexy. That is a long application though.

whoa, i think you miss understood me, partly because i f#cked up my post. For a rod in compression, above the chainstay, I agree that a hollow ti rod would be just about perfect. Below the chainstay, in tension, maybe not, but as you've already stated, you won't be producing anything like that. I was just posting weight/info for reference....not to criticize you.

 

[jet]

Yeah. I was thinking that solid would be more flexy than hollow. On the other side; if you do happen to bend one, a solid would prolly bend back more than hollow. This may not be an issue with TI.

Will TI fold? I have never seen this. Has anyone else? I know it will break.

I need to get a TIG welder. And a lathe. And a jig.

I would love to build frames. Anyone from ABG on here?

 

[zedro]

Man, everybody is a critic.
Ti is quite a bit cheaper than carbon, and easier to work with.

well how much is your Ti tubing? quick search for CF tubes came up with 0.625"/0.520" @$33.60 per 4' (133.3g)


and gosh, just throwin stuff out there. If you dont want comments, post yer spam in the classifieds....

 

[zedro]

btw, i used 5/8" x 3/16"t which is way overkill, but i needed some meat to thread some 1/2" bolt ends into for extra adjustability.

 

[dG video]

btw, i used 5/8" x 3/16"t which is way overkill, but i needed some meat to thread some 1/2" bolt ends into for extra adjustability.

Holy crap dude,

Did you make that bike?

How does it ride? Any pics of the full bike?

Dan

 

[amateur]

Why go with a press fit? They make weld-in bungs for heims. IMO, fiber would be a better option, and if you're offering something, why not offer the whole thing(heims included)

 

[buildyourown]

I didn't mean to be snappy about the comments. You can give me all the flak you want. I'll take it as constructive criticism.

As for the choice of material: I found the tubing for about $18 a foot. So it is just a bit cheaper than carbon. I'd be suprised if the carbon one ended up being lighter. My friend is making a crabon one so we can compare when he's done.

amateur: I've never seen heim ends in Ti or in this small of a size. I bought some steel ones for my truck but they fit 1.25" ID. I don't make my own Ti ones cause it is overkill and Ti is a bitch to drill and tap. As for not including the ends: These are readily available and people won't nessecarily need new ones. They can reuse their old ones.

 

[DHS]

well i want one dammit

 

[kdog-rider]

would it work on a Giant DH

 

[buildyourown]

would it work on a Giant DH

Yes it will

 

[xy9ine]

speaking of heim ends, where could i find some in aluminum? (m8, male). i've seen them on some brooklyns & brake therapy kits. the only one's i've found online are imperial.

 

[buildyourown]

speaking of heim ends, where could i find some in aluminum? (m8, male). i've seen them on some brooklyns & brake therapy kits. the only one's i've found online are imperial.

I get mine from McMaster-Carr.
I have snapped the steel ones though so I don't think I would run the aluminum

 

[spookydave]

speaking of heim ends, where could i find some in aluminum? (m8, male). i've seen them on some brooklyns & brake therapy kits. the only one's i've found online are imperial.

Give these guys a call. I bet they have them in stock. They can even get them in ti but you better have the budget of an Indy team.

http://www.bakerprecision.com/

 

[randalliser]

There's some cheap Ti tubing that could be good here

 

[Sverre]

There's some cheap Ti tubing that could be good here

I saw that erlier. Looks interesting. I'm not sure about the wall-thickness..?

S

 

[zedro]

I saw that erlier. Looks interesting. I'm not sure about the wall-thickness..?

S

that would be fine being 3/4 OD

 

[shock]

Hi, late to the party as usual, but I thought I'd interject some pertinent data......

Our aluminum rods start out as 1/2" od, and are drilled on each end. In an 18" length, are 145 grams. We do make them for super 8"s in this size...borderline flexy? hasn't really been a problem, and absolutley zero failures/problems.

Our carbon rods in the same length weigh 60 grams. With aluminum oversize rod ends, 120 grams. BTW, the aluminum rod ends are stronger than an m8 steel rod end.

Someone said they've broken steel m8 rod ends??? I'm assuming they weren't ours (brake therapy). As far as I know, we've had no failures, if someone knows otherwise, please let me know (braketherapy@therapycomponents.com)

What else, euler's deal, not entirely relavant for the problem at hand, smaller diameter allows more tire/suspension clearance. Solid aluminum rods have plenty of strength/stiffness for the job at hand. Tubes are much more vulnerable (including our carbon rod) but for the weight weenies among us, can save grams.

I say our aluminum rod can be run over with a truck and still be bulletproof. The carbon rod, you gouge it or damage it, you replace it.

Tension vs. compression. That's why we make floaters with the rod above the swingarm, I'm not really comfortable hanging the rod and/or any brake component below the swingarm. I have a hard enough time keeping the derailler on the bike, but I can still make it down the hill without a rear de. Without a rear brake I crash.

So, Buildyourown, I would suggest at least a crimp fitting or structural adhesive to bond the end into the arm, yes even for compression applications. It's pretty embarassing when you try to hold the bike on an uphill with the back brake and the rod end pulls out (don't ask me how I know this).

But I think ther is a place for the TI rod, it fits inbetween the aluminum and carbon rod in weight and price, so it gives everyone another choice, all good.

Mmmm, tried to cover everything, I'm sure I missed something, and I'm sure someone will let me know if I did.

 

[zedro]

i'm kinda surprised alot of the floaters use solid rods....

 

[shock]

i'm kinda surprised alot of the floaters use solid rods....

Well, for all our "standard" floaters, we use a solid rod, drilled a super secret amount on the ends. Main reason, we stock over 10 different lengths, so cost/benefit ratio comes heavily into play. Reason #2, clearance. Especially for a bike like and M-1 or Stab, where you have to fit the rod inboard of the seatstay and still provide tire clearance. Reason #C, absolute bullet proofness, as I said, you could run over the solid rod with a truck and put a 30 degree bend in it, and it wouldn't fail.

Funny thing is, an "unnamed" oe customer of ours had a hollow rod that they said was lighter. When we weighed them, our solid rod was lighter, as well as cheaper and more reliable, with better clearance.

Tubes are good, but when you bring all the consideration in, not necessarily better

 

[zedro]

well the .625/.375 rod i use weighs about the same as a 0.5" solid rod actually....but of course is stronger .....it's a pretty overbuilt rod..err tube.

yeah those proper M8 rod ends are pretty burly. The ones i've seen on BB7s were complete junk tho

 

[shock]

well the .625/.375 rod i use weighs about the same as a 0.5" solid rod actually....but of course is stronger .....it's a pretty overbuilt rod..err tube.

yeah those proper M8 rod ends are pretty burly. The ones i've seen on BB7s were complete junk tho

Zedro, does anyone ever tell you... no wait, how many people tell you that you spend way too much time on these boards....

So, of course you are correct, the rod size you mention is almost identical in weight, (and tensile strength) to a 1/2" solid rod (unless you have to weld in inserts in the end, in which case it is then heavier). And of course it is stronger in torsion (irrelavant) and has less tendency to buckle. But, as both are overbuilt (remember burly has been banned), that strength difference doesn't matter. And you can't use an m8 rod end in that size tube (without inserts), so there...

I could (and probably am) be wrong, but weren't the bb-7 rod ends 6mm (as are Foes) but even if they were m8, yes the quality of those were crap, which is why we use a much better quality rod end. But then again, our stuff costs too much money.....I remember seing a bb-7 at Whistler with a bent rod end, and when I pointed it out to the owner, he got mad at me, like I was bashing his bike or something.....

 

[zedro]

Zedro, does anyone ever tell you... no wait, how many people tell you that you spend way too much time on these boards....

So, of course you are correct, the rod size you mention is almost identical in weight, (and tensile strength) to a 1/2" solid rod (unless you have to weld in inserts in the end, in which case it is then heavier). And of course it is stronger in torsion (irrelavant) and has less tendency to buckle. But, as both are overbuilt (remember burly has been banned), that strength difference doesn't matter. And you can't use an m8 rod end in that size tube (without inserts), so there...

I could (and probably am) be wrong, but weren't the bb-7 rod ends 6mm (as are Foes) but even if they were m8, yes the quality of those were crap, which is why we use a much better quality rod end. But then again, our stuff costs too much money.....I remember seing a bb-7 at Whistler with a bent rod end, and when I pointed it out to the owner, he got mad at me, like I was bashing his bike or something.....

gimmee a real job and i'll lay off the boards....

well using that tube allows for a bend in my case, but also will take a side impact better, ie. bending forces (which i noticed, carefully omitted ). My main point was, i could go lighter even and retain the important strength factors. Inserts are no biggy IMO. I just thought using Al-tube was a more cost effective way of reducing weight

You might be right about 6mm rod ends, but i could still tell the steel quality was garbage. At 4-5$ a pop, theres no reason to cheap out on something decent that'll save the day.

 

[shock]

Ha, real job, so you mean not bike related. Or my "day job" in car racing, also not a real job. Okay so I've never had a real job myself, what's your point....I'm actually unemployable in the real world, so I just hang out with flakes like me....

As for cost effective, here's a question...which is stronger, a solid rod with a gouge, or an equivelant cross section tube with a gouge?

Also, a solid rod drilled and tapped, or a tube with seperately machined rod end ends welded in?

Bottom line to me? I've seen tubes with the equivalent cross section fail (maybe because of damage, maybe because of inferior quality (ie, available tubes are 6061, and our rods are 2024)

And again the expense, yes I agree, why skimp on a few bucks for cheap rod ends, but when you're trying to produce a commercial product, every dollar counts. Believe me, on this point I'm not arguing, but I have to try to reduce costs without reducing reliability, and the solid rod (drilled on the ends) seems to win. That's why all our stuff ends up being stronger (and more expensive) than other products.

And cheap rod ends suck

 

[zedro]

Ha, real job, so you mean not bike related. Or my "day job" in car racing, also not a real job. Okay so I've never had a real job myself, what's your point....I'm actually unemployable in the real world, so I just hang out with flakes like me....

As for cost effective, here's a question...which is stronger, a solid rod with a gouge, or an equivelant cross section tube with a gouge?

hehe, like my job interviews where i wear a nice shirt and slacks rather than a thick coating of dirt and sweat, thinking "wtf am i even doing considering working in this egghead infested cubicle land of misery....i want to play with grease!"

the cost effective part was a reference to the Ti thing (original point of the thread), rather than the solid dealy-os.

material-properties based arguments always produce the worst threads :dancing:

 

[dw]

What else, euler's deal, not entirely relavant for the problem at hand, smaller diameter allows more tire/suspension clearance.

How exactly are you calculating buckling load in a compressed element if Euler buckling isn't relevant? Its not only relevent, its necessary in my opinion. Maybe I just like calculating things though...

Case in point, Profile DH bike. I personally had to modify several of them at Platekill a few years back because the rods were buckling. Hit the rear brake, rod buckles into the wheel, wheel locks up, suspension locks out, you crash. A quick run of the Euler buckling equation showed that the section was just too small.

Anyways, carry on

Dave

 

[ThePriceSeliger]

i still dont understand the difference of the ones your making compared to the ones comming stock on a Gemini DH. I know you eplained it earlier but I am not very good with tech talk, so will you tell me in normal person language please.