What fork is this
Oh those numbers look very good for a mostly road fork. I get why a-c is an important dimension to consider for overall bike geometry, but I wish we also had a standard measurement for the distance from the center of the dropouts/ta holes to the lowest point on the inside of the crown.
Also, for wiggle bikes in particular, would longer and thinner fork legs do some work keeping things floppy, or is there a point at which you want some stiffness in the legs for wheel tracking but more give in the headtube?
Iāve considered the latter a lot, as my bikes usually have a 220-250mm ht. Iāve gotten a lot of feedback from framebuilders over the years about how that much headtube can be a little flexy. Iāve always assumed that a headtube, with headset and steerer in it, is going to flex way, way less than the comparatively free legs of a fork, but maybe itās doing different work, keeping the frame in line while the fork legs are responding more to changes in the road surface.
As I type this out I realize that this is probably something that Jan Heine or Craig Gaulzetti has written about pretty extensively, and Iāll be thinking about this more when my Endpoint wiggle machine shows up.
Isnāt a headtube flexing just the tt and dt flexing? Could imagine a long ass steerer having some flex, but headtube itself just doesnāt make sense to me.
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Yeah Iām wondering what twisting the ht is resisting
Right, I guess lateral flex on the headtube is a thingā¦ but doesnāt seem like a thing that youād want.
Yeah, people whose opinion I trust, after running the numbers for frame dimensions that would work for me, usually recommend a very beefy steerer
Steerer flex is a thing - Breezer used to make a rigid MTB fork that necked down from 9/8" to ~1" in the middle to give the fork some more flex.
But I canāt see there being any significant flex coming from a head tube.
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I feel like the head tube is coupled into the bottom bracket swing. Is that planing?
headtubes for tapered steerers lead engineers to make everything else bigger too, especially the downtube
Tom Ritchey gives that as his explicit justification for making off-trend forks like this:
Ritchey did a talk with Grant where they got into that at NAHBS last year.
He wasnāt wrong, just an asshole.
I feel bad for starting this thread and never making anything happen. Just donāt have the $. If anyone does and wants to make something cool I can get you in touch with the best factory there is.
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Oh, I think we figured nothing would happen, since several hundred $500 unicorn forks is kind of a weird thing to go broke over.
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Longer headtube will change how the front ātriangleā responds to load, if you think of it as as a four bar linkage with pivots at the HT/DT and HT/TT joints, in a way that could be could easily mistaken for steerer flex
Archibald Sharpās 1896 book did an analysis of what frame dimensions would have no torque on the headtube joints while JRA. That turns out to have nothing to do with how we pick frame geo but I think itās relevant to flex.
the trick would be to also make a rack and frame to go with it
why bother if youāre only going to go a little broke?
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Precisely. And without an import business for parts to support the frame experiment how do you even survive?
Ah, makes sense, I think. So itās more of a twisting that wouldnāt really recruit the steerer as a stiffening member?
Sounds good.
Weāll need someone handy with FEA, and someone who is real good at surfacing in SW.
Tooling cost for a full size run of frames and forks would be at least a 100k. Factory enginerds can handle layup. You can count on paying for a fair amount of scrap while nailing that down and then passing ISO fatigue and impact tests. Maybe a trip or two to Shenzhen.
So 200-300k later you have your <1500g planetastic crabon unicorn frameset. And each one from here on out costs a few hundred bucks FOB.
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and by the time you maybe sell most of the initial run, you have to redesign things for new equipment standards?
wow the bike biz is brilliant!!
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Not saying I actually want to do this butā¦ has someone who actually knew what they were doing successfully brought a frameset to market through crowdfunding?
Assuming the design work is done when you launch your campaign you could probably deliver the frames less than a year after getting the funding.
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hey @EndpointBraden @Andpoint_Endy yāall awful quiet over thereā¦
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