Broken SKS longboard - what to do?

Hi all,

My Pompino’s rear fender cracked at the seat stay yesterday, much to my disappointment. I’d had the guards fitted for around 1.5 years, and probably covered a couple of thousand kilometres with them.

The hole in the seat stay bridge faces down, meaning that the only way to attach them was to drill a hole in the fender. I had a little rubber washer on the seat stay bridge, and a regular washer on the inside of the fender.

I have done some reading online, and found that other people have experienced this. My questions:

  • Is this due to stress caused by the fender constantly being in tension, in addition to having been weakened by me drilling the hole through it?
  • Would drilling a slot rather than a hole help with this? I figure it would allow some adjustment to have the fender sitting more… naturally.
  • Should I just buy another set of the same, or try something else? Anybody had experience with Planet Bike Cascadia fenders?
  • Would aluminium fenders fare any better? I’m no materials engineer! I was checking out some Cascadia ALXs online, but I would have to drill them too.

Here are some pics of the break for reference:

Any ideas would be most welcome!

The fender must have been installed under tension, so vibration has fatigue cracked it. In future, careful spacing at the CS bridge and adjustment of the attachment at the stays and prebending the stays so they sit in the same place when unbolted as when bolted would mitigate this. Likely the hole also had a nick or something that helped the crack start, filing/sanding the hole smooth would help, a slot wouldn’t help much as the tension on the fender would still exist.

Repair: Cheap option is to repair the one you have. Get some gorilla tape from bunnings, mate the faces, tape them together. Then get some thin (1-2mm) metal stock, aluminium would be easiest to form and work with, make some brackets, one for the outside and one for the inside form to the fender profile and attach them to the guard, either a couple of pop rivets on each piece or some M5 bolts and nylocs. Attach the guard to the eyelet with a hole through the brackets.

Replacement guard:

  1. Do the same installation but ensure it’s fitted with no residual stress, aluminium guards will suffer the same fate.
  2. Install a formed aluminium brace to the guard and bolt through that in addition to (1), could have a single one on the inside but be sure that you don’t just move the failure point to the end of the brace…
  3. Use the supplied clip on/ slide on seatstay bracket and add a small 90º bracket (ask your local LBS for something from their rack parts bin) to that to bolt it up to the eyelet.

Zip tie it and forget about it. Had this happen a few times. But read above, incorrect installation.

Oh, yeah, x’d zip ties, that’s easily the quickest repair. Gorilla tape the halves to seal from spray, drill holes, file/sand any burrs, and x stitch it with zip ties. Plus the zip ties will allow it to flex.

I had an SKS that had a partial crack, drilled a crackstopper hole at the end and then stitched it up. No worries.

Well that was quick! I should also mention that I did re-read your excellent excellent recommendation thread before pulling the trigger on this too :slight_smile:

Noted. I also find it slightly more challenging with a single speed bike since I have to take care when adjusting or removing the rear wheel.

I already annoyingly snapped the front fender at the lower stay attachment as I had clipped one too many gutters etc, so I think it’s worth starting anew with a fresh set. Fortunately I have another set of new longboards sitting in my garage waiting to go on my girlfriend’s bike. I believe her seatstay bridge has a horizontal-ish facing hole, meaning I will have to use that bracket to mount the fender. Nonetheless I will use this as a valuable lesson in tension minimisation. However, how do you get good fender line AND keep the tension to a minimum?

Noted: another pair of longboards it shall be!

Forgive my lack of imagination, but how would that angle bracket help if the hole in my seatstay bridge faces the fender? Attach angle bracket to seatstay bracket? But then how do I screw this into the downward facing hole in the seat stay bridge?

Thank you again for your time. Helpful as always!

P.S. The bottom bracket you gave me when I bought your splatter pedals and the spacer from you has served me well since I have had the bike, but now I have its replacement in my bag, ready to install. Thanks yet again :slight_smile:

Use the quick release brackets from your broken front fender on your new rear fender, then pop the stays out when removing rear wheel. It won’t make the prettiest fender line, but maybe set it up at the rearmost wheel position so you won’t be pulling it back and adding tension to the guard.

horizontal dropouts and perfect fender line / stay setup is unlikely to happen.

To get the best setup you can, you’ll have to bend the stays, a bend at the dropout end so they’re not trying to flex outwards, tweaks on the ends of the stays so if you loosened the bolts they wouldn’t spring away in any direction. 2 pair of pliers or channel locks will help you make clean bends.

seatstay bracket on guard, bolt 90 degree bracket to seatstay bracket, then bolt through the other hole in the bracket to the frame eyelet.

… And then slide the fender onto the bracket. Will investigate!