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PostPosted: Fri Aug 10, 2012 10:18 am 
Dirt Disciple

Joined: Mon Nov 14, 2011 2:10 pm
Posts: 70
Ok, this may seem like a bizarre call for help to you old hands, but I was brought up on MTBs with vertical dropouts. Frankly, horizontal dropouts on geared bikes just baffle me, they seemed designed to introduce error into the tracking of your rear wheel.

Anyhoo... I can't get my rear wheel to stay straight. I'm running fairly fat 32-630 (27 x 1 1/4) tyres, which leave only a few mm clearance at the chainstays. I've wound the dropout adjuster screws all the way back to get the wheel further back and maximise this clearance, and I'm using a high quality Allen-bolt QR's which I'm torquing up hard. I'm sure that, when my wheel goes on, the clearance is even between the chainstays. However, pretty soon I start getting tyre rub on the left chainstay. I could take the adjuster screws out completely to get even more clearance but frankly, I'd rather know that my wheel was staying put. So, is there something I'm missing?!


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PostPosted: Fri Aug 10, 2012 11:27 am 
Retro Guru
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Joined: Wed Apr 25, 2012 2:08 pm
Posts: 2185
Location: Shrewsbury
Sounds like as you pedal the tension is skewing the rear wheel, so it can't be tight enough.

Have you taken a close look at the QR as you tighten it. It could clamping against the end of the axle but not tightening against the drop out properly. If so it could be your axle is to long.

Take the skewer out completely, then slide your wheel back into the drop outs. The axle should be about the same or slightly shorter than the space between the drop outs.

If you measure the inside gap between your drop outs the overall axle length for quick release is ideally plus 5.5 mm on each side.


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PostPosted: Fri Aug 10, 2012 12:14 pm 
Dirt Disciple

Joined: Mon Nov 14, 2011 2:10 pm
Posts: 70
Robbied196 wrote:
Sounds like as you pedal the tension is skewing the rear wheel, so it can't be tight enough.

Have you taken a close look at the QR as you tighten it. It could clamping against the end of the axle but not tightening against the drop out properly. If so it could be your axle is to long.


Thanks R, that did actually just occur to me. I was planning to repack the wheel, so I'll check that I have even amounts of axle sticking out beyond each locknut and that it's not wider than the dropout.

On a similar note, I thought I'd resolved the problem in my last round of fettling. I'd mounted the conical spring on the QR skewer on the wrong side so it was sandwiched between the dropout and the QR nut. Putting on the correct side (where the QR nut has a recess to take it) means the nuts are both flush against the outside of the dropout, but it still slips!

I guess mounting a wheel in horizontal dropouts is just something that I never saw my Dad (or anyone else) do, so I've just not worked out the "knack" for doing it. Is there a particular trick?


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PostPosted: Fri Aug 10, 2012 12:25 pm 
Old School Hero

Joined: Fri May 18, 2012 11:24 am
Posts: 194
Location: London SW
You need a QR with internal cam, like Shimano or Campagnolo... external cam ones do not hold the wheel strongly enough in horizontal dropouts...


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PostPosted: Fri Aug 10, 2012 12:30 pm 
Dirt Disciple

Joined: Mon Nov 14, 2011 2:10 pm
Posts: 70
ugo.santalucia wrote:
You need a QR with internal cam, like Shimano or Campagnolo... external cam ones do not hold the wheel strongly enough in horizontal dropouts...


I'm not using QRs, I'm using these Allen bolt skewers, which I'm torquing up with a long-arm Allen key.


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PostPosted: Fri Aug 10, 2012 12:32 pm 
Retro Guru
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Joined: Wed Apr 25, 2012 2:08 pm
Posts: 2185
Location: Shrewsbury
It should be straight forward, but you need the check that axle length.

Here's a vid: http://www.youtube.com/watch?v=Z8fB5ySntcA

Another point, if you've wound the drop out adjuster screws right out use those to square up the wheel, then tighten the QR.

Can you post a pic?


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PostPosted: Fri Aug 10, 2012 1:19 pm 
Dirt Disciple

Joined: Mon Nov 14, 2011 2:10 pm
Posts: 70
Robbied196 wrote:
It should be straight forward, but you need the check that axle length.

Here's a vid: http://www.youtube.com/watch?v=Z8fB5ySntcA

Another point, if you've wound the drop out adjuster screws right out use those to square up the wheel, then tighten the QR.

Can you post a pic?


Well my dropouts and adjusters are pretty standard, like the ones in the first picture here except that I'm using Allen-bolt skewers rather than QRs.

Part of the problem I'm having is the need to constantly pull the wheel backwards against the tension of the chain so that the axle is hard up against the adjuster bolts. Obviously I'm having to do this one-handed since I need the other one to use the Allen-key to tighten the skewer. I find this a problem even with the chain on the smallest chainring and smallest sprocket. Do you usually drop the chain off the chainring when mounting a rear wheel?


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PostPosted: Fri Aug 10, 2012 1:30 pm 
Retro Guru
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Joined: Wed Apr 25, 2012 2:08 pm
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Location: Shrewsbury
Its the derailleur that tensions the chain, but from the way you describe it, the chain sounds to short. If your on the small chain ring at the front and the smallest sprocket it should be easy to push the wheel back into the drop outs.

Have you had a new chain fitted? If the chain is short that could be causing your problem. A new chain should be wrapped around the largest chainring and the largest sprocket without going through the derailleur, pull the two ends together then add one complete link. Break the chain at that point and fit it as normal through the derailleur.

You could try winding the drop out adjusters all the way in. This in effect lengthens the chain so there's less tension.


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PostPosted: Fri Aug 10, 2012 5:46 pm 
Old School Grand Master
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Joined: Fri Oct 14, 2011 8:41 pm
Posts: 8226
Location: Cumbria
Chromed dropouts ?

Shaun


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PostPosted: Mon Aug 13, 2012 11:51 am 
Dirt Disciple

Joined: Mon Nov 14, 2011 2:10 pm
Posts: 70
Midlife wrote:
Chromed dropouts ?

Shaun


No, nothing that flash, just painted Suntour dropouts.


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