Thru axle tolerances

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Ravnsnaes
Posts: 103
Joined: Thu Dec 22, 2005 2:48 pm
Location: Denmark

by Ravnsnaes

I'm in the process of building up a new bike. I find that the front wheel is very loose fitting and hard to align, because the fork legs are 102mm apart instead of the specified 100mm for standard thru axle fitment. Is this considered normal? The manufacturer says so, but I have yet to come across such a loose fit on any other brands.
Just want to check wether or not to make a deal out of it.

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eucalyptus
Posts: 527
Joined: Thu Mar 19, 2020 3:51 am
Location: Sweden

by eucalyptus

My latest fork (Chinese) also had 102 mm gap

My Italian made Basso is 100mm spot on (incredible workmanship on the fork)

When I asked around 100mm +- 2mm appears to be okay tolerance. Not saying I agree with this. But the fork tightens up around the hub once installed.

I haven't had any problems so far

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joejack951
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Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE
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by joejack951

As someone in the thru axle business, I can confirm that 102mm is technically in spec. The fork specs I’ve seen when I’ve gotten my hands on original drawings are all 100 mm +2/-0. Now, manufacturing any product where you are right on the edge of your spec is generally considered poor quality control. Any slight change to the process could send that dimension out of spec; ideally everything is produced centered on the spec and with plenty of leeway above and below. But this is the bike industry so I’m completely not shocked to see forks at 102 mm spacing (or slightly more).

It does make fitting a wheel more annoying, especially if you have loose fitting end caps, like say the 15 mm end caps that Bitex supplies. Once thru axle is tightened you’ll never notice the wider spacing, assuming the fork ends are close enough parallel when drawn in to 100 mm.

mikemelbrooks
Posts: 345
Joined: Wed Jun 16, 2010 10:58 pm

by mikemelbrooks

I have a Chinese replacement fork in my TCR and it's very slightly too narrow. Having to prise the fork legs apart while aligning the disc in the caliper is a real pain.

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ultimobici
in the industry
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by ultimobici

mikemelbrooks wrote:I have a Chinese replacement fork in my TCR and it's very slightly too narrow. Having to prise the fork legs apart while aligning the disc in the caliper is a real pain.
Not to mention a bad idea long term.


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