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Help with Mag 21 Rebuild/Tuning

4K views 3 replies 3 participants last post by  felixcurly 
Hi alltogether,

this is my first post in this forum. Normally I am reading/writing in german (vintage) bike forums. But I couldn't get the help I need so I am trying my luck here.

I have a Rockshox Mag21 fork for my Specialized S Works Mtb. While rebuilding it, I did not only want to change the seals and O-rings, but I also would like to adapt it to my rider weight (~62 kg). Rock Shox has a nice manual, which I tried to attach here.
Following this manual I should choose the following setup:
  • softer valve spring (25lb)
  • no "valve spring preload", so no washers under the vavle spring
  • compression bleed hole with 1,5 or 2mm (depending on cross-country or downhill use)
  • no rebound bleed hole or 2x1,0mm (depending on cross-country or downhill use)
I have the disassambled fork here on my work bench (see pictures below). No coming to my problems... :oops:;)
  • Do you agree with the proposed setting? any propositions?
  • How do I know which valve spring I have? I should be able to check that by compressing the spring. The manual says there is a 25lb and a 40lb spring - but which length change should the spring make under this weight?
  • Honestly: I do not understand where the compression or bleed hole(s) should be.
  • what does this sentence mean (from the manual): "valve plates are a tuning variable. The .005” relief step machined into plates used from 1994-97 improves small bump response"
Thank you very much for your patience and help - I am looking forward to your comments!

Felix

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Hello Felix I can help you with all your Mag 21 problems. It's too much to write it all down here. Just send me an email to b_tight11@yahoo.de
Then we can change phone numbers and I will send you the information you need to setup the Mag 21 properly to your weight specifications. You can also make a tuneup to 63mm travel. I will tell you also how to mix the fork oil close to manufacture settings.
Greetings Jürgen
 
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