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So some of you may have spotted my earlier post asking for feedback on different suspension designs for XC racing and some help designing a frame- [url= http://singletrackmag.com/forum/topic/singletrackworld-please-design-my-bike-for-me ]here[/url] and I have finally come up with something resembling a rocky mountain element as I'm yet to find a significantly bad review on them - and they look pretty sweet too!
But the one thing that has come up about them is that they use 165x38mm shocks, and that although they are good for a little weight saving over a longer design (eg 200x50), and give me the ability to make the frame a bit more compact, I have heard that they suffer on small bump compliance and generally aren't as good as a longer shock. I can see this being true as you would have to run a higher pressure to get the right amount of sag, but is this actually true?
I know there won't be anyone out there that has been able to use both in the same frame due to frames being designed around a specific shock, but has anyone got or ridden two similarish bikes but with different size shocks (preferably of the same design) - and can give me a definitive answer if longer shocks are better?
For XC racing, I'd suggest that you're looking for efficiency rather than out and out suspension performance. As such, the smaller shock being 'less good' than a bigger one is less of an issue. In fact, it may arguably be better suited if it actually reduces some bobbing (due to stiction).
I had a RM element (though a much older one - 2003 IIRC). Until it broke, it was probably my favourite bike. I'd get another one if I could justify it.
The shock was fine and no doubt, current shocks are better than the one I had on it then.
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I hadn't thought about it like that! - I guess a small amount of stiction will help reduce bob.
I also assume it won't be too detrimental to the small bump compliance - but from doing a bit of reading that doesn't seem to be an issue!
Does the shock length relate to shock travel or % percentage of volume remaining at full travel? The former will affect stiction whilst the latter will affect spring curve.
Larger air volume/shock body = better heat dissipation.
Longer shock will have more volume and feel more linear. For the same amount of travel it'll have smaller leverage ratio so you can get away with using less pressure.
But remember you can tweek the leverage ratios by using linkages so you can have it feeling supple in beginning stroke for small bump compliance and then firming up quickly in the mid stroke to keep good efficiency.