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Right, I've got a 2006 Cannondale Rush that still has its stock Float R rear shock. Its supposed to have pro-pedal but its so bouncy on the flat and uphill its useless!
I'd like to upgrade to an RP23 but the problem is the shock to fit the rush is 190x44.5mm (7.5x1.75in) which i can't even seem to order new, let alone find a secondhand one.
However there are plenty of secondhand RP23 and RP2's with 190x50 and I'm tempted to fit one.
I cant see any cross bracing on the swingarm that could hit the frame, and the rear wheel is miles away (its an XL frame so is even longer than the standard bikes)
I realise it'll increase the travel to about 123mm, and will invalidate any warranty (not that i've got any being the bikes second owner)
Any other reasons not to? Can i reduce the travel of an RP23/2 anyway?
I'm sure that if you sent it off to TFT they'd reduce the travel but if it was mine, I'd use it as is first to see how it feels if you're confident nothing will clash.
Have you spekn to TF about your current shock? My bet is that a push tune on your current shock would solve all your problems.
Have you measured the travel on the frame minus the shock? The frame swingingarm design might be what limits the travel rather than the shock itself, so the 50mm might not be a problem. (in fact I am 90% sure this will be the case)
steveh has a good point though, be maybe worth investing in the shock you already have.
The issue may not be the shock fouling the frame it's more likely to be the -ve effect on geometry.
Lengthening the shock will increase the seat and head angle, lift the BB as well as shortening the wheelbase, all not good ideas from a handling point of view.
You can of course increase the sag to combat this when the bike is static but it will still extend to these dimensions when you're out riding.
I personally would'nt recommend it, however if you do go ahead I may have a 2010 RP23 Boost Valve shock for sale which is 190x50. ;o)
Poisonspider - He's not suggesting lengthening the shock, only increasing the amount of travel the shock has...
poisonspider, the shock he is on about is the same length, so that doesnt apply.
Have you measured the travel on the frame minus the shock?
Yep, its pretty much unlimited untill the wheel hits the seat tube. There is no bracing across the swingarm 2006 bikes unlike the newer bikes that would foul.
I've just had the shock out and made up some cardboard spacers to mimick a 140mm shock (190 - 50) which is what the RP23 should be at full travel and the tyre is pretty close i.e. 3mm to the seattube. Whats the chances of getting more than 50mm travel from the shock?
Have you spekn to TF about your current shock? My bet is that a push tune on your current shock would solve all your problems.
I've considering it, however came to the decision that a float is always going to be a 'Jack of all trades, master of none' shock and i would like to have the option of setting the propedal on the fly.
Also i quite like the idea of increasing the rear travel to around 120mm
Well a 190x50 shock will have a minimum compressed length of 140mm.
If you take the existing shock out, can you cycles the swingarm to give you 140mm eye to eye without anything fouling? If so, the shock will fit.
Alternatively, as others have suggested - get the existing shock serviced/Pushed/custom tuned, which might well end up being a better performing product.
3mm is pretty low clearance - now admittedly you're unlikely to do it very often but...
A slightly fatter/bigger tyre could mean it rubbing.
I'd give TFT a call and ask them about it.
mojo or tf can put a limiter on the shock shaft to limit the stroke to 44mm, i think thats what cannondale do to a standard 190x50, might be worth unscrewing the air can on your existing shock and having a look to see if the shaft inside has a spacer to limit the stroke,