RS Mag 21 servicing


Old School Hero
Does anyone service old RockShox Mag 21’s?
Been offered a bike with some on.
Just want know if it can be done, and how much it might cost.


Retro Guru
One day I'm going to pull mine apart and swap the lowers onto my Paris Roubaix forks and I'm planning to do a rebuild video. No promises on when though. Go to get a disk brake adapter to fit the replacement Bomber Z2s first.


Retrobike Rider
Orange 🍊 Fan
Wadsy does this sort of thing on a pretty regular basis - but not sure how busy he is at the mo.
Give him a try


Retrobike Rider

Yeah, you'll find that and more in the archive here ... e/Service/

The cost of a full service is not really in my opinion worth it for the fork, unless you do it yourself.
I've services quite a few and rebuilt from part many over the past 10 years or so I've been on here.

When you get them
- Pump them up, you'll need needle in a pump (basketball/football) to do that.See if they then piss the air back out.
If not, you're good for now

Then pop the caps off, poor some oil out see what it looks like.
If horrible or you just want to do it anyway, buy some 5 wt oil, unless you are on the heavier side (see sutherland tweaking manual) and add a bit to each and flush out what you can a few times.
Then fill with out, fit caps, set the oil level and pump up and go for a ride (you can buy nice pumps of ebay that have a dial at the low pressure up to 60 PSI range).
If they loose air over time, you can make/buy/get me or somebody else to fix the air seals for you, should be no more than a tenner maybe.
Give them a go and tweak.

If other stuff happens, like oil out the main seal or warn bushes, they can be replaced but you need to split the forks apart.. which can be done at home without the tools most of the time.

Have fun, have a go, oil doesn't cost that much.

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