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Increasing Tire Clearance on Steel Fork

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Increasing Tire Clearance on Steel Fork

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Old 09-14-18, 07:19 PM
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Colnago Mixte
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Increasing Tire Clearance on Steel Fork

I have an older Mangaloy fork from an '86 Univega Gran Rally that needs a couple more mm clearance to be able run 28 mm tires.

I was wondering if it might be possible to add some material into the inside of the fork dropout to get a tiny bit more tire clearance, or would this even work? I have a mapp gas torch, silver rod and flux, as well as some experience.

The fork has no "lawyer lips" and there seems like there's plenty of clamping area to hold the front wheel on safely. Pic is not my fork, it's just for illustration.
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Old 09-16-18, 05:14 PM
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JohnDThompson 
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On track forks, it's not uncommon to file the underside of the crown for tire clearance. If you're using a crown-mounted brake (as opposed to cantilevers or V-brakes that mount on the blades), take care not to compromise the mounting hole.
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Old 09-16-18, 05:22 PM
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No, it's a road bike running 700 x 28's. The tires clear, just barely. I would like to have another mm or two of clearance just to avoid constantly scraping dirt off the front tire with the brake calipers. Fork crown has 3 or 4 mm clearance, but the brakes are a couple mm lower.

I tried out all the road brake calipers I have and found the ones that clear the tire the best, some old 1980's Shimano single pivot calipers. I may just file them down a little, but I would rather not if i can avoid it.
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Old 09-16-18, 11:07 PM
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Doug Fattic 
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Yes it probably would be possible to braze some additional material in the dropout to increase the length a mm or 2 from the axle to the brake hole as long as its slot is long enough. After cooling they could be filed carefully so the wheel will center. Of course once you start playing with heat its possible to extend its length by replacing the dropouts too. They vary in length and it is possible to find longer ones. For a frame builder with a fork fixture this would not be a big deal. However doing it with simple tools to check alignment and length and rake to insure accuracy increases the challenge a lot. There are ways to do this and the method I would use if I wasn't in my well equipped shop would be to braze one dropout in 1st and make length and alignment corrections before brazing the 2nd one on..
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Old 09-16-18, 11:18 PM
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I don't know of it helps, but my Campy Veloce dual pivots have plenty of clearance for my 28mm tires, and got them for $40 on chainreaction
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Old 09-17-18, 01:18 AM
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I had very tight tyre clearance with my Campag Centaur brakes - the skeleton ones dating from about 2006

I recently fitted an Ultegra R8000 groupset to this bike and was very surprised and pleased to find that the tyre clearance increased by at least 3mm possibly as much as 5mm. I didnt take any exact measurements.

They brake much better too.

If you measure from centre of the mounting bolt to the underside of the brake caliper, I will do the same and you can see what the difference is and if it might sort your problem.
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Old 09-17-18, 06:44 AM
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Here's the situation. Looks like I already have essentially maximum clearance on the brakes.
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Old 09-17-18, 08:36 PM
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OK, I did some tests, and by placing the axle 1/8th inch lower in the front dropout, this gives me about 1/8th inch more tire clearance.

I think that I can fabricate some sort of insert to place into the fork dropouts, it doesn't necessarily even have to be metal. And I ought to be able to just JB Weld it in there. In theory anyway ...

Will report back if anyone is interested.
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Old 09-17-18, 10:29 PM
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Mr_Asifi 
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I'm interested, just in case I might need to do so in the future. I saw a cool Peugeot PSN 10 on here with gravel tires, which I'm hoping I can put on my bike eventually. Hate having to avoid certain paths because of the gravel/dirt
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Old 09-18-18, 06:09 AM
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I think this would be a very easy and useful mod for people who can clear bigger tires in the back but not up front. And if I can figure out a way to successfully use JB Weld instead of brazing, it could work on any fork including carbon and aluminum.
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