answer my riddle!
ok, so where did our frequent posting go, yikes!!
anyway here is a conundrum I am in these days, see if you can answer it:
(I’m pretty sure it’s a recurring issue I know the solution for, which I’ll pipe in with later.)
when I am pedaling along at a normal (~75rpm) cadence under a light to moderate load (generally flat terrain) on my mountainbike I have a distinct slipping feeling at my left foot with each revolution as the foot passes the top (12:00) dead spot. it has the feeling of a loose pedal or loose crank or even a poorly adjusted cleat. seeing as how none of these have turned out to be the culprit, please help me try to solve the problem. as a note, I do sometimes have the feeling that pedaling smoother circles can somewhat diminish the issue, and also that it may seem to go away on longer rides (maybe I just forget about it.)
in the interest of science I have replaced the pedals, with a new pair of a similar model; I have replaced the cleats with a new set; and I have tried a second set of same model shoes with their old cleats; none of which have alleviated the issue.
clean drivetrain
now for some tech specs:
frame: Moots, 29er ybb with S&S couplers (which were checked and verified to be tight)
cranks: RaceFace Deus (verified tight, then taken apart cleaned regreased, and retightened)
chainring: a single Blackspire SS chainring (cleaned, checked, and not sharkfinned; all bolts tight)
bb: RaceFace X-type (replaced with stock replacement 10 months and <1200km ago)
pedals: CrankBrothers Eggbeater S (regreased; 4yr olds but rebuilt by CBros 16 months ago)
chain: Rohloff S-L-T-99 (cleaned, no significant wear; perfect SS chainline)
rear hub: Rohloff Speedhub 500/14 CC DB OEM (no outward sign of wear; 100% functional shifting)
rear cog: Rohloff steel (cleaned, no significant wear)
btw, everything is always (85% of the time) lubed and cleaned directly (within 3-4 weeks) after every ride. and all (~35%) rides take place in ideal (or possibly rainy, muddy, or snowy) conditions.
that’s about it.
lots of little checks and the problem persists.
leave questions and answers in the comments!
-cory
I’m not familiar with the X-type crank? Is that an external bearing crank? What type of interface between BB spindle and crank arm does it have? I know you checked the arms, but that’s exactly the feeling of a loose crank/BB and regardless of which side is slipping, you’d feel it in the left pedal.
Usually, it’s the left arm that’s causing the problem. If the cranks uses a tapered spline (like the XTR 952 style) the common problem is when they’re compressed onto the spindle before the splines are properly indexed. The splines can be broached slightly bigger when the crank bolt is tightened and since the end of the BB is tapered, you can crank the arm on hard and it will feel tight until you ride it again.
Something similar can happen on the drive side arm but it’s unlikely. The drive side arm is broached and then the splined spindle is pressed into place. It’s possible that the spline has deformed and is allowing the spindle to move in the arm (unlikely).
My official guess is that it’s not non drive arm “spline hole”
so first, it is an eXternal-TYPE BB.
the left crank arm is pressfit to the spindle.
the drive-side arm attaches via a ~10 sided non-tapered spline.
the spindle’s splines seem to have been indexed properly (even after triple checking); although I admit that it can no longer be verified that it wasn’t at one time forced on while improperly indexed.
with the RaceFace X-type system, the crank arm is tightened to a physical stop, not to a certain torque on a tapered spindle. (so once they are loose, they stay that way, herein lies the problem.)
btw Sean, its kind of cheating for you to answer first.
I was expecting one of the regulars who is more full of shit and less analytical; more likely to have some hare-brained solution and less likely to be pretty much right from the get go.
oh well, it’s still not really solved yet.
-c
blah blah i rode dellars bike once and it had a bent crank arm, same feeling.
we all know race face makes machined doo doo, and that sugino xd 500 crank arms are superior in everyway.
Sorry, I’ve experienced this in relationships too. When presented with a problem, I often attempt to provide a solution rather than to go round and round while continuing to discuss the problem, why the problem is problematic and how the problem makes me feel.
What I should have written (given the context of the blog) should have been more along the lines of … Find something French, with really really small internal bearings and a square taper spindle. Or get something the pre-dates square taper spindles that was hand hammered by someone with an Italian sounding last name. It may not fit right or work really well, but that’s part of the point. Ride that shit and HTFU. Would Sean Kelly (cyclings Chuck Norris?) try to find a solution? WWSKD?
no worries señor lightheadedness.
I do appreciate the straight talk actually.
(and I haven’t a clue WWSKD, so I’ve just replaced a little worn-out rubber washer that kinda preloads the bb bearings and may end up with a shard of a pilsner urquell can in there somewhere to augment the spindle’s splines a bit. we’ll see?!)
The Eggbeaters. They are junk and will automatically make your pedaling feel like garbage just by installing them. The sesame seed sized bearings do it every time. Replace them with these and all of your problems will be solved.
can I get those in grade A american beef patties?
tarnation!
my two cents takes the form of story for which there is no explaination.
quaint as kelp, amazed i would be t’was not a great help!
a french bike once i hadcar-bones, durr-ah-chi, perfect for this young lad.
most cricks and squeaks and clacks and creaks would vanish with a bath, a tweak a grease–but the worst of them gave me ascension with no peace. crickety slip, wiggity wack. the crankset! the crankset! what is this crap! eleventy pieces this internally bearinged bottom bracket, broke a little e’ry day–shimano’s a bloody racket.
er…raceface…same deal.
best comment ever.
been reading finnegan’s wake?
It sounds like your SAE legs do not interface with the Metric mud in the Czech Rep. Also I have never know you to have a bike that was in good enough repair to notice a issue like that. If it rolls, stops and is fully custom I say RIDE THAT BAD MOTHER FER, RIDE. Move back and I’ll take a look.
Since your feet are not the same size, try wearing two socks on your left foot.