Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

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

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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

Old 08-06-18, 02:55 PM
Senior Member
Thread Starter
TallRider's Avatar
Join Date: Oct 2005
Location: Fresno, CA
Posts: 4,451
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Likes: 0
Liked 4 Times in 4 Posts
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.

TallRider is offline  
Old 08-06-18, 03:18 PM
Senior Member
CliffordK's Avatar
Join Date: Nov 2014
Location: Eugene, Oregon, USA
Posts: 23,513
Mentioned: 182 Post(s)
Tagged: 0 Thread(s)
Quoted: 9739 Post(s)
Liked 312 Times in 247 Posts
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.
CliffordK is online now  
Old 08-06-18, 04:12 PM
mechanically sound
frankenmike's Avatar
Join Date: Jan 2007
Location: Dover, NH
Posts: 1,501

Bikes: Indy Fab steel deluxe, Aventon cordoba, S-works stumpy fsr, Masi vincere, 92 Hardrock commuter, Dahon mu uno, Outcast 29

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked 15 Times in 12 Posts
I’d go with option 3 (and thanks for making this thread easy to reply to!)
frankenmike is offline  
Old 08-06-18, 04:19 PM
Senior Member
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 31,748

Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!

Mentioned: 34 Post(s)
Tagged: 0 Thread(s)
Quoted: 1255 Post(s)
Likes: 0
Liked 83 Times in 71 Posts
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.
HillRider is offline  
Old 08-06-18, 04:24 PM
Join Date: Mar 2013
Location: TX Hill Country
Posts: 5,936
Mentioned: 87 Post(s)
Tagged: 0 Thread(s)
Quoted: 1110 Post(s)
Liked 144 Times in 93 Posts
'74 Raleigh Internat'l. '77 Trek TX900 FG. '90 Vitus 979. '10 Merckx EMX3. '13 Soma Stanyan
Bandera is offline  
Old 08-06-18, 05:04 PM
Bad example
Join Date: Nov 2015
Location: Seattle and Reims
Posts: 2,930
Mentioned: 33 Post(s)
Tagged: 0 Thread(s)
Quoted: 773 Post(s)
Liked 17 Times in 14 Posts
I have successfully trimmed fenders with a Dremel so they fit between fork legs or seat stays.
Keeping Seattle’s bike shops in business since 1978
Aubergine is offline  
Old 08-06-18, 07:01 PM
Senior Member
dsbrantjr's Avatar
Join Date: Sep 2010
Location: Roswell, GA
Posts: 6,571

Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta

Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 799 Post(s)
Likes: 0
Liked 124 Times in 105 Posts
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.
dsbrantjr is offline  
Old 08-06-18, 07:16 PM
3alarmer's Avatar
Join Date: Nov 2010
Location: The Big Tomato
Posts: 17,716

Bikes: old ones

Mentioned: 248 Post(s)
Tagged: 0 Thread(s)
Quoted: 15697 Post(s)
Liked 320 Times in 274 Posts
...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.
3alarmer is offline  
Old 08-06-18, 07:53 PM
Senior Member
Thread Starter
TallRider's Avatar
Join Date: Oct 2005
Location: Fresno, CA
Posts: 4,451
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Likes: 0
Liked 4 Times in 4 Posts
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.
TallRider is offline  
Related Topics
Thread Starter
Last Post
Bicycle Mechanics
01-02-19 08:44 AM
Classic & Vintage
10-28-16 03:55 PM
Bicycle Mechanics
06-21-13 12:51 PM
Bicycle Mechanics
03-05-13 11:30 AM
Long Distance Competition/Ultracycling, Randonneuring and Endurance Cycling
05-15-11 07:17 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.