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I’m contemplating grabbing a Commencal Meta TR frame, but I plan to run it with my current ‘23 Pike Ultimate which is ‘only’ 140mm.
To even it out a touch I was pondering getting a 50mm stroke shock instead of the usual 55mm (it comes without a shock so this is free reign). The latter yields a 140mm year travel - what would be the likely travel of a 50mm, and will it have any other notable impacts on geometry?
Ta
If its a metric shock static geometry is unaffected, you will simply run into the bumper at 140/55*50mm of travel (or near enough, progression has a small effect). So you will get 127mm ish of travel, and you will find your BB slightly higher and your angles slightly steeper if you were to set the same %age of sag for your 55mm shock as the new 50. But not so much you would likely notice.
(140/55)x50 = 127mm travel. Based on a Linear relationship, so near as damn it.
But is actually more 'out of sync' with your fork than it would be anyway. Its very common to have more travel at the front, but theres no actual defined reason why you cant have more at the rear. I'd go with what the frame is designed to have.
This would help the geometry if you’re keeping the fork at 140mm https://reverse-components.com/en/products/05%C2%B0-angle-spacer-tapered-forks 140mm front and a shorter stroke shock to give you 127mm would be pretty balanced and that reverse components spacer would bring the geometry back closer to where it should be with a longer fork.
Shorter fork than recommended will steepen the head & seattube angle 0.5° - 1°, the reverse crown race is the answer or Wolftooth extender headset cup, I'd stick to the correct stroke rear shock, lessening stroke won't resolve the actual geometry issue just shorten the travel and alter the suspension characteristics by putting the bottom out 13mm earlier.
Treat yourself to new longer forks
A shorter fork will affect geometry, a shorter shock (assuming eye to eye is the same) will maintain rear geometry just mean less travel.
Actually, a shorter stroke shock will mean less sag which will make the whole bike a little steeper as well.
As above, treat yourself to a longer fork.
Thanks all.
Bizarrely, the geometry chart posted on the Commencal site lists the recommended fork height as 551mm, which is what the '23 Pike Ultimate is - except that is 140mm, when the frame is supposedly designed around 150-160mm... *shrugs*
My thinking around running a shorter stroke shock isn't to try to correct the geometry, BTW. It just made sense to me to run a shorter shock to balance the shorter fork travel. Plus I'm coming from a hardtail, so I don't 'need' 140mm of rear travel - the bottom-out happening 13mm sooner is still 127mm longer than it has been until now!
A longer fork may happen, but I need to buy wheels, a new dropper and new rotors before I can even finish the build, so longer forks will have to wait a while.
A) Get the 55mm stroke shock, but reduce the volume with volume spacers. Ramps up quicker, will use less travel (unless really needed), and can be easily changed yourself if/when you get a longer fork… unlike changing the max stroke which can be tricky to do at home with many shocks.
B) Get the 50mm shock and also get it with 5mm shorter eye to eye. Less travel, slackens things back off to match the shorter fork… just watch pedal/ground clearance… might need shorter cranks or thinner pedals.
In the end I ordered a Knolly Fugitive instead - they're clearer about what a 50mm stroke shock and 140mm fork does to their geometry and I have a line on a cheap SuperBoost wheelset, plus Commencals are *everywhere* over here so it'll be nice to have something different!