My wife's bike has a fork by RST, Sofi.

Definitely a budget fork, however is working quite well for the occasional use.

I saw that the the seals rings are quite damaged, and I was looking to substitute them.

I cannot find any manual online, and furthermore there isn't the classic screw on the bottom...

How do you open such low-cost forks and service them? enter image description here enter image description here

  • bicycles.stackexchange.com/questions/43232/… and bicycles.stackexchange.com/questions/57934/… are relevant pre-existing questions. One has instructions, the other has an assembly diagram that should help.
    – Criggie
    May 16, 2021 at 0:03
  • Thanks for the reply, however the issue here is: I do not have the "4mm hex bolt on the bottom of the slider leg". So I was wondering, before to open the fork, is someone had experience on that case.. Maybe directly from top accessible...
    – Profeta64
    May 17, 2021 at 9:03
  • @profetea64 hmm - maybe, it could be this fork is designed to be unserviceable ? That's a guess Could you post some clear and well-lit photos of your fork? That might help jog someones memories. Use edit to update the question.
    – Criggie
    May 17, 2021 at 9:21
  • Could be that it is unserviceable... But I do not find any details about that... However it is funny, because officially exists available the rst sealing ring as spare parts..
    – Profeta64
    May 20, 2021 at 10:23
  • Excuse-me, do you know the seal kit diameter? Feb 5, 2023 at 9:28

1 Answer 1


On similar forks I've dealt with, the trick they're playing is that the coil spring inside is the part that joins the upper to the lower.

Hidden inside the lower, there's a threaded boss welded in, and a bolt threaded into it. It's an M5 cap screw from what I've seen, although there could be variations. You access it by poking a 4mm allen socket on a long extension down through the coil spring. This secures an unusual looking round "block" which has unusual screw threads form on the outside. The fork spring threads over it, and the whole assembly is secured to the lower with the cap screw.

There's another such "block" that secures the top of the spring to the upper. If memory serves, on the one I've taken apart, you get that threaded out of the spring with a 5mm or 6mm allen fitting that's exposed once you remove the preload adjuster.

The preload adjuster comes off with a plastic wrench that RST sells. If you're willing to accept some marring, you can typically get them off and reinstalled with improvised tools.

I have no idea whether replacement wiper seals are available, and doubt this is worth dealing with even if they are. It's grease-lubricated inside and the grease is thick and lasts a long time, intended never to be opened or serviced.

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