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when the driveside crank is at the top of it's rotation and I push down hard on the pedals, there is a little kind of loose notchiness at the top of the downstroke
it feels like the chain is sitting slightly off the tooth and engages as I push on the pedals, it gets worse the more pressure I put on, it doesn't make a noise but I can feel it in my feet
there are no tight links in the chain and nothing I can see wrong with the chainring, cranks are on tight with no noticeable play, the chain, BB and cassette are only a few hundred miles old
therefore I conclude that it's the chainring
is there something I'm not thinking of? pedals maybe?
Could the chain or chainrings be worn..?
worn chain'n'rings
Sounds odd *leftfield* loose pedal?
Does it happen when the non-driveside crank is at the top of its rotation? If not, then it suggests it must be a 'one-sided' issue, i.e pedal, crank, or a BB cup.
Check for play in pedals, and that pedals are tight on the cranks?
Check that chainring bolts are tight? Check that there is no play in either the cassette or freehub?
Do you use SPDs? Something to do with the cleats...?
if it was me I'd think my knee was on the way out!
bent pedal axle ?
even though its fairly new - have you checked the BB? when did the issue start - before or after you fitted new drivetrain components?
Do what the other STWers do when there bike makes funny noises.
Buy a new one of course!
it started last week, about a month after fitting the new parts.
I did have an issue with a tight link in the chain which caused it to snap when it was brand new - I wonder if I have bent the chain or chainring when this happened, although I don't think it's the chain as the issue is once every crank rotation
there is some play in the pedals (eggbeater candies - I know of the issues with these crank bros pedal) so will check them
sounds to me like something isnt lined up right. have you got all spacers in the right place / crank arms on the BB enough? dont mean to sound patronising, only mentioning it as i've done em all before!
Check no lateral movement or knocking in the cranks that indicates a BB problem. Check derailler alignment sometimes get a slight twist in the hanger when a chain snaps this can make slight chain cassette problems under load
good luck
What cranks? If Raceface I'd say knackered splines allowing the driveside crank to move in & out, sounds very similar to my symptoms.
FSA carbon cranks (road bike)
Octalink BB
.
my first check when I ride it home tonight will be to try and replicate the problem in the middle and granny rings as I've only noticed it in the big ring as that's all I use, that will point out whether it's chainrings or not
on closer inspection, forceably trying to move the non-driveside crank laterally recreates the movement
I'm hoping it's just a bit loose, can't believe the BB would fail after only a couple of hundred miles
+1 Pedal bearings or loose cleats?
Don't suppose you've installed a BB mount chain guide by any chance have you? I had this sort of problem when I was running my DMR speed guide, soon as I took it off it went away. Bit of a long shot but that was my experience!
How old are the cranks?
could be worn out crank arms, causing play between the arm and the BB splines. My other thought was a worn out chainring but after reading your last post I don't think it's that, but if the teeth look like shark teeth then it'll need binning anyway.