"dookie" <
[email protected]> wrote in message
news:[email protected]...
> the mag21 is air sprung and oil damped.
>
> the knobs on top of the legs adjust compression damping only.
Not really. It's actually a blow-off valve, to adjust the lock-out threshold. Tightening it will
lock the fork except on the biggest hits. People were concerned that fork movement would absorb too
much pedaling energy, thus the adjustable lock-out. Bontrager modified the forks that came with his
bikes to eliminate this feature, and they worked very well.
> spring rate is adjustable by changing the air pressure in each leg. 80-120psi as previously stated
> will blow the seals in a heartbeat...30-50psi is more like it. inflate/deflate with a standard
> ball needle, *greased* and inserted through the hole in the center of the damping knobs. yes,
> these seals are fragile, and virtually impossible to find replacements for these days. also, there
> isn't much air volume in the legs, so if you use a floor pump go *slowly* .
>
> rebound damping can be adjusted only by changing the oil weight...10wt was oem i believe...5wt or
> even 3wt, especially in conjunction with higher air pressure and a low compression damping setting
> was 'the hot setup' and resulted in a much more supple ride. to change the oil, deflate the legs
> by inserting a loose needle (ie: not attached to a pump) in the fill port, then loosen the bolts
> in the crown that clamp the legs in place and unscrew the (long winded) top caps of each leg. dump
> the old oil out and refill...*don't quote me on this*, but i believe the correct oil volume is
> ~2cm from the top of the leg, about as deep as the top caps extend into the leg.
>
> i just sold my mag21, but rode the **** out of it for a long time. it was a great fork in its day,
> and while a bit fragile, very reliable if properly maintained. i had mine totally rebuilt by rock
> shox a couple times, and replaced the top air seals a couple times more myself. if yours doesn't
> have boots over the stanchions, get some. also, keep an eye on ebay for a rebuilt kit, which
> includes pretty much everything you'll need to keep it up (including instructions)...except for
> the top air seals.
I don't think they were fragile at all. In fact, they were more durable and reliable than anything
else, until very recently. However, most forks since the mid-90 outperform the Mag, which by modern
standards is too flexy and doesn't have enough travel.
Matt O.
