Hello all, I got this bike (2013 CUBE AMS 120 Pro) yesterday and it's my first full suspension setup. After I aired up the shock I noticed it bangs into the frame when it's fully extended.
Further investigation showed me this shock is not original to the bike. The original shock measurement was 200 x 51 and the shock currently on it is a 216 x 63
My question is, when shopping for a replacement do I have to get exactly a 200 x 51 shock? Is there a method to determine what the maximum size is? 200 seems like an uncommon size and I can only find what looks to be one decent brand available as NOS on ebay. I see a lot more that are 205 x 60 though…
by JeveStones69
3 Comments
I haven’t owned an FS in awhile, but if I recall correctly, the first measurement is the length (entire unit) and the second measurement is the stroke (the portion of the shock that actually compresses which may or may not be the entire length of the “stanchion”)
Best bet is to check with the manufacturer and/or an owner’s group for that specific bike, because if there is a combination of measurements that work, they will be able to tell you.
The larger number is the more crucial one, but you should try to exactly match the shock specs for the bike as weird things may start to happen on the fully-compressed side of the travel otherwise.* The concern here is strange things happening with the lever rate of the frame mid-stroke and further on a longer shock, where the frames lever rate and original shocks spring rate were designed to be matched in a certain way. If you increase stroke you will have a low spring rate at what was designed to be a very deep point in the frames travel, and crashes may happen behind the seatpost, or in the worst case wheel-onto-seat tube.
I would also look *very* carefully at the seat tube where the shock has been crashing into it. If I noticed this on a frame I would fully pass on it for fear of unseen damage there (and gross incompetence elsewhere in rhe bikes maintenance history).
*Unless you really know what you’re doing or have a good reason to do otherwise, I would even try to exactly match the stock shock tune as well.
Most likely the previous owner wanted to increase the rear travel from 120. But judging by the 20% sag marker being so close to the seal, and the shock is already touching the frame, their calculations were totally wrong lmao. In theory you could get 148mm of rear travel with this shock at the cost of a steeper ht angle among some other minor things.
Maybe, just maybe this shock allows for travel adjustment. Service it and see if you can put tokens in the negative chamber, a -1cm will bring it almost back to spec and the bike will become usable. No need to splurge money on a replacement shock