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Cantilever rear hub offset from centerline

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    Posted: 15 November 2021 at 10:54pm
I think some of Burrows bikes were like that? Are there any caveats?
As far as I recall, they felt a bit weird at first, but than completely normal... should your seat centerline lie on the 'diagonal' between the wheel contact patches for best effect?
I want to build one because it seems simple to do using tech available to me (3d printing + carbon tubes).

I've had the hub itself laser cut:


Some people said that headset bearing might not work well for that purpose, but I think they should do just fine - after all, I've personally seen them used as *suspension* bearings on DF (Gt Force) MTB, so they should take radial loads with gusto, and being 'angular contact' they should work particularly well for a cantilevered load I think...

I want to try my hand in creating a new (carbon) frame for my 90 deg angle FS MBB - I want it lower, lighter and more aero, but retain full suspension front triangle.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote AlanGoodman Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2021 at 3:02am
Never even noticed it on the Ratracer or Windcheetah to be honest…
Both handle fine.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote XAPBob Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2021 at 8:59am
Windcheetah - I was wary of it initially, and the trike is fractionally less stable turning hard right, but it's not significant.

The hub and axle are, of course, items that are likely non trivial to get replacements for - but you're making them yourself which makes that a moot point.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Balor Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2021 at 9:02am
Great! I'll proceed with that.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Balor Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2021 at 5:29pm
Well, that was the easy part.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote XAPBob Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2021 at 3:50pm
Looking nice, I like the transitions, I presume you've actively decided on all the different profiles.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote russellbridge Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2021 at 4:27pm
Personally I don't like offset rear hubs - the few times I've ridden Ratracers I immediately noticed that the bike had a lean on.  I'm sure you get used to it, but I didn't like it
Russ
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Balor Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2021 at 11:33pm
Originally posted by russellbridge russellbridge wrote:

Personally I don't like offset rear hubs - the few times I've ridden Ratracers I immediately noticed that the bike had a lean on.  I'm sure you get used to it, but I didn't like it
Russ

I think it should be completely fine if you weight will be centered on the line between contact patches.
That means that your seat will need to be offset on that line as well... funny thing is, I already need this kind of offset, because I need a fairly large pedal extender on the right foot (my feet are somewhat deformed).

By moving the seat to the left, I would not longer need it... maybe I'll need one on the left now, but I can live with that :).
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Balor Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2021 at 11:38pm
Originally posted by XAPBob XAPBob wrote:

Looking nice, I like the transitions, I presume you've actively decided on all the different profiles.

Yea, I've thought that since I have that option, I might as well try and add some passive suspension by 'grading' the core in 'tail' region (outlayer is actually TPU! Fairly rigid for tpu, about like car tires) and going w/o inner carbon tubing.

Since I'll be be mostly using thick carbon sleeve, it should be massively stiff in torsion, stiff laterally due to 'fishtail' highly ovalised geometry but flexy in vertical plane. How flexy.... remains to be seen. I can simply add more carbon layers if things not stiff enough.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote russellbridge Quote  Post ReplyReply Direct Link To This Post Posted: 23 November 2021 at 10:59am
All looks good and well thought out. Are you using 'wet lay up' carbon fibre, or 'pre-preg' with an oven?

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