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Curved fork unicrown restricts fender - How to get more clearance?

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Curved fork unicrown restricts fender - How to get more clearance?

Old 08-06-18, 02:55 PM
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TallRider
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Curved fork unicrown restricts fender - How to get more clearance?

I'm mounting Planet Bike Hardcore fenders on a 1989 Panasonic mountain bike, to use as a commuter. This is the 26" version of the fenders designed for traditional mountain bike tires. The fender is 58mm wide, and the fork blades are 69mm apart, but the curved unicrown of the fork keep the fender from being as high as it should be. I'm not worried about tire clearance (these fenders are for rain and dust, the bike won't be ridden on gravel) but it would be nice to mount the fender closer to the crown and use the mounting slot correctly.

I think my options are:
a) cut/dremel out the top of the metal mounting slot. fender stays fairly close to the wheel, hanging from a longer, more exposed bit of steel
b) bend the fender in between the fork blades - it's flexible plastic, although I suspect this will introduce stresses that crack the fender
c) file or dremel a divot in the corner of the fender where it contacts the fork blades, so that it can slide further up. this may weaken the fender, but only the unweighted part that sticks ahead of the fork, and there will be plastic above and below the divot.

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Old 08-06-18, 03:18 PM
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Many vintage fenders were shaped to go around the fork blades.

I'd be tempted to do option:

D) Heat and shape the fenders. Maybe a paint stripper, or there is a mini version of heat gun at electronics stores for shrink wrapping.

Or, perhaps

E) Try to find better fenders.
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Old 08-06-18, 04:12 PM
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I’d go with option 3 (and thanks for making this thread easy to reply to!)
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Old 08-06-18, 04:19 PM
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I'd also go with "option C", the Dremel, to notch clearance in the fender, or use a heat gun per "option D"recommended by CliffordK to accomplish the same narrowing of the fender where it hits the fork blades. I wouldn't modify the mounting bracket to allow the fender to stay close to the tire as some clearance between them is required for safety.
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Old 08-06-18, 04:24 PM
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"c"
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Old 08-06-18, 05:04 PM
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I have successfully trimmed fenders with a Dremel so they fit between fork legs or seat stays.
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Old 08-06-18, 07:01 PM
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Option C. Leave plenty of clearance to avoid rattles; you do not need a particularly close fit in that area. For extra style points finish the raw edge with something like this: https://www.amazon.com/Edge-Trim-Bla.../dp/B00KG9BAY0 Use a bit like this, https://www.amazon.com/Dremel-561-Mu.../dp/B00004UDIB the rotary saws won't work well.
As for D I would be concerned that the heat gun might have unexpected/difficult-to-control results, but if you could fixture it properly so the curve doesn't get distorted.it might work.
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Old 08-06-18, 07:16 PM
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...if I were doing this, and tire clearance was not an issue, I would just manufacture something from metal strapping that would allow me to extend that metal mounting strap thingy. I have plenty of leftover stuff from fender mounting kits where it would not be problematic. Just a simple flat piece of metal with two holes, one on each end, in whatever length you require.
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Old 08-06-18, 07:53 PM
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Thanks everyone! The dremel worked. I just cut a rectangular piece out, leaving a ridge along the bottom of the fender for support in the vertical plane (so the unsecured part of the fender in front of the fork isn't popping up and down. The plastic stuff is pretty tough, and the squared-off edge of the fender seems designed for durability while riding on bumpy surfaces. Or maybe the design is there b/c a lot of MTB tires have a more squared-off profile.
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