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Using 28c tires with a recently purchased carbon fork, I found I had only ~1mm of tire clearance from the top of the brake caliper. However, if I mount my wheel slightly lower in my fork ends so that it just clears the lawyer tabs, but is no longer flush with the top of the fork end, I have a more acceptable ~3mm of tire clearance.

Is there any danger in riding my bike with my wheel mounted in this way? I am using QR skewers if that matters.

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    You'll need to clamp the wheel pretty tightly to the dropouts to stop it moving - possibly causing damage to carbon fibre. If the wheel moves back into the dropouts after hitting a bump, you wheel could suddenly jam against the fork.
    – Nic
    Commented Jun 23, 2016 at 20:20
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    It sounds like a recipe for something bad to happen, if it does slip back all the way in after hitting a bump and the tire bottoms out it will be more expensive than just getting a different tire. Also even 3mm is not a large space between wheel and fork. Sounds scary to me..
    – Nate W
    Commented Jun 23, 2016 at 20:26
  • Can you change the brakes?
    – Chris H
    Commented Jun 24, 2016 at 6:41
  • Don't do it! Going downhill at a good speed you hit a bump and the axle slips. You go head-over. People break their necks that way.
    – Daniel R Hicks
    Commented Jun 24, 2016 at 12:02
  • Would Surly monkey nuts work for you? Stick them on the skewers and go. They might need s tiny bit of filing so you are retained by the lawyers tabs. Aluminum is quite strong in compression.
    – zipzit
    Commented Jun 25, 2016 at 2:03

2 Answers 2

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The QR interface is designed such that the axle is fully seated in the dropouts before engaging the QR. The QR engagement should be firm, but it is not designed to hold the wheel in the way you describe. Dangers of trying to do what you suggest are:

  1. Severely over-tightening the QR (which you may need to do to keep the wheel in place) could potentially result in QR breakage. If the QR breaks there will be nothing to hold your front wheel on and there is a very good chance you will end up in a bad crash.
  2. If you do not seat the wheel, it is easy to accidentally clamp on an angle. Given you want to clamp a fair ways down in the dropout it is easy to get really off-angled if you are not paying attentions. As in (1) if you are severely over-tightening this could damage the drop outs and contribute to problem (1).
  3. Even if you can get this to work, 3mm of clearance is still incredibly tight. Tires can expand and contract with temperature and speed (meaning this clearance could start to disappear) and small debris picked up by the tires could result in a jammed wheel (briefly giving you the ability to fly).

If something does go wrong my bets are on (1) or (3). The short of it, is that your frame simply isn't designed for 28mm tires. This is the issue with short reach caliper brakes (now what most define as standard reach). Frames with mid-reach caliper brakes can support tire sizes up to around 32-35mm depending if you want to run fenders as well.

Unfortunately, the N+1 rule has struck again...

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  • I would betting on debris being the problem. I've seen old-school bent wire tyre scrapers ripped off by surprisingly large chunks of stuff that stick to the tyre (bigger than goatheads). Even a goathead is going to cause distress with 1.5mm clearance, get a wet day and a bit of gravel and I'm not sure you'd superman so much as slide out. Be interesting to perform the experiment..
    – Móż
    Commented Jun 24, 2016 at 1:10
  • @Móż did those old wire tire scrapers work?
    – Rider_X
    Commented Jun 24, 2016 at 3:23
  • Some people swore by them, but IMO they were better combined with the horizontal flap to take the water off, because when you're dealing with very, very rare events like punctures it's really hard to tall. I am having trouble searching for them effectively, but I vaguely recall looking ages ago and not finding any useful stats. I'm not convinced, but if I ran skinny tyres I'd be tempted to experiment (my 406-38 marathon plus generally wear out before they get punctures)
    – Móż
    Commented Jun 24, 2016 at 4:16
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I've got this exact case on my road bike. 23mm tyres were too horrible, 25 were better, so I went to a 28mm tyre and I have about 1.5 mm of space between the brake bridge and the rolling outside of the tyre.

And its not caused a single problem in 500 km of riding to date.

The only way it could cause a problem is if your tyre was bulging from being off the clincher-hook, or if something was stuck to the tyre, like mud or snow or similar.

Mount the wheel properly - that's the single most important part of this answer. Then deal with the fag-paper clearances if it becomes an issue.

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    It may have worked out so far...
    – Rider_X
    Commented Jun 24, 2016 at 3:32
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    Are they fully slick tyres? Because there are plenty of 28mm tyres match as my marathon plus) that have just which groove to hold stones that stick out by more than this.
    – Chris H
    Commented Jun 24, 2016 at 6:40

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