Creaky crank with play and loosening

[lateral_G]

Crosspost from Reddit.

I have a Cannondale road bike with a BSA bottom bracket (I think; I need the Park Tool BBT-9 to remove them) and a Truvativ Elita 2-piece crankset with splines. I've been having a creaking issue on the right (drive) side for quite a while now. It happens during the bottom 1/3rd of the right-side pedal stroke. There's also a little bit of play on the right side (i.e. I can sort of move the crank teeth towards and away from the frame).

First time the creaking started, I took everything apart, cleaned the bottom bracket and the crank axle/splines, put it together, and torqued the left-side crankarm to spec. I don't remember what resource I used, but I believe I greased the bearing faces under the seals (that the crank arms press against), the part of the frame they mount into, and the splines that the left-side arm mates with.

Second time it started, I just kept putting it off till the axle of the crank started sticking out a little on the drive side (I could see about 3-4 mm of the splines) and the chain suddenly fell off the crank one day, after several days of creaky riding. I removed the left-side arm, used a mallet to tap the axle flush with the face of the crank disc again, and tightened the bolt again, but this time a little harder. Both times, the creaking stopped immediately after I re-assembled everything, but slowly started again after a while.

Please shed some light on what I need to fix/replace. Is it the bottom bracket, the crankset, or both? I took it to a local bike shop but they weren't very helpful.
Also, how do I go about finding out the inner diameter(s) of the bottom bracket bearings? I don't think there are any diameter markings on the current ones, only the torque spec, tightening direction, and "32-06" (don't know what that means).

[Jesper]

(07-08-2020, 06:36 PM)lateral_G Wrote:  Crosspost from Reddit.

I have a Cannondale road bike with a BSA bottom bracket (I think; I need the Park Tool BBT-9 to remove them) and a Truvativ Elita 2-piece crankset with splines. I've been having a creaking issue on the right (drive) side for quite a while now. It happens during the bottom 1/3rd of the right-side pedal stroke. There's also a little bit of play on the right side (i.e. I can sort of move the crank teeth towards and away from the frame).

First time the creaking started, I took everything apart, cleaned the bottom bracket and the crank axle/splines, put it together, and torqued the left-side crankarm to spec. I don't remember what resource I used, but I believe I greased the bearing faces under the seals (that the crank arms press against), the part of the frame they mount into, and the splines that the left-side arm mates with.

Second time it started, I just kept putting it off till the axle of the crank started sticking out a little on the drive side (I could see about 3-4 mm of the splines) and the chain suddenly fell off the crank one day, after several days of creaky riding. I removed the left-side arm, used a mallet to tap the axle flush with the face of the crank disc again, and tightened the bolt again, but this time a little harder. Both times, the creaking stopped immediately after I re-assembled everything, but slowly started again after a while.

Please shed some light on what I need to fix/replace. Is it the bottom bracket, the crankset, or both? I took it to a local bike shop but they weren't very helpful.
Also, how do I go about finding out the inner diameter(s) of the bottom bracket bearings? I don't think there are any diameter markings on the current ones, only the torque spec, tightening direction, and "32-06" (don't know what that means).

Welcome "G",

How old is your bike, what model is it, did you buy it new, and approximately how many miles do you have on it? BSA refers to the threads, thus I assume it's a threaded BB and not a press fit. I think the 32-06 is in reference to the bearing O.D. and depth 32mm x 6mm. If you can see the bearings they would have a number on them that you can look up which specifies their I.D., O.D., and depth. You need a micrometer to measure them accurately (not expensive), but most use whole mm dimensions and not fractional sizes (i.e. 32.5mm) so you can use a metric ruler with mm increments.

Sorry to hear that the "bike shop" was unable to, or wouldn't help you; after all servicing bikes is their job!

Apparently there have been many problems with the BB shell tolerances on many bikes (manufacturer defects), but I believe that this primarily relates to "press-fit" BB type shells.

This type is certainly not my specialty. Perhaps someone with first hand knowledge with this will reply. I am just starting to build up newer frames using these types of BBs so I am still in the learning process myself. I have heard of "press-fit" BBs making creaky noises by more than one rider so it seems to be a relatively common occurrence.

Again, why couldn't the bike shop give you some insight since they are supposed to be the "experts". Did they remove/dismantle anything, or just spin the crank arm and/or pulled and pushed it to check for play? To a certain degree it sounds like the crank is loosening on the axle splines, be it from the bolt holding it on or damage to the crank where it mates with the axle, thus the play. The only other play you can have is the loosening of the threaded cup or the bearing itself being worn (which you wouldn't be able to correct or "quiet down" without replacing the bearing itself). Have you closely inspected the mating part of the crank for any wear or damage?

I'll try to research this since I know I'll be dealing with it in the near future and I would like to avoid the same problem.

Post a couple photos if you can.

Take care,
Jesper

[lateral_G]

Hi Jesper,

Thank you for your detailed reply. I don't know the post etiquette/convention here at Bikeride, so I didn't quote your reply. I thought my reply would become too long otherwise. If that's not how it's done, I apologize.

My bike is a Cannondale Synapse, but I'm not sure which model/year. I bought it used in 2016 from someone who was using it for training, I think. I myself put maybe 1500-2000 miles on it, most of them in the first year. There's a "C4" on the stem that holds the handlebar and a "C2" on the seat post, but I think the previous owner put a lot of aftermarket parts on it - it has an Easton fork, an aftermarket handlebar, the SRAM Truvativ crankset (which definitely doesn't seem stock coz the color is different), Shimano wheels, and Shimano 105 brake/shifter levers and derailleurs.

Yes, the BB is threaded. It's apparently a GXP and had the words "Truvativ" and "Sealex" on the face of the bearings. I believe that's an SRAM set, right? I tried turning the inner races of both sides around. The drive side was turning more smoothly than the non-drive side, even with the bearing seals off. With the seal on, I wasn't able to turn the non-drive side very well, but that's probably more due to not being able to properly exert pressure on the race directly with my finger.

I'm sure you're right about the crank being the issue. Even with the crankset removed from the bike, the crank disc was wriggling a little on the axle. I think I actually overtightened the BB, so I don't think its looseness was the issue. So I'm guessing I'll have to change the crankset. I'll probably throw in a bottom bracket as well. Do all cranksets have the same axle length (i.e. the distance between the two ends of the bottom bracket)? I know there are different crank arm lengths, but with so many different bottom bracket types, I wasn't sure if any crankset would fit any bottom bracket in terms of diameter and axle length. How do you normally choose the BB-Crank combination?

Lastly, the bike shop said they'd only be able to work on my bike in 3 weeks or so. For checking it, they didn't remove anything. They just tried to tighten the (already overtightened) left-side crank arm. I showed them the play in the crank myself, so they said maybe my bottom bracket is loose.

Thanks again for your insight. I added some images to this URL: https://imgur.com/a/wTyE1fj

[Jesper]

[quote='lateral_G' pid='39098'


Thanks again for your insight. I added some images to this URL: https://imgur.com/a/wTyE1fj
[/quote]

If I only had some real insight to your problem via experience! I'm still learning. I will chat with my friends and see what develops. I will say that if there is play between the crank arm and the axle it might not be repairable without being creative and having certain materials at your disposal. Something I have is brass shim sheet stock that l use to "fit" parts on old bikes which would otherwise require professional machining and pressed sleeves, etc. I think my thinnest is .003 inches. It will essentially conform to the 2 mating parts filling the worn out or damaged space between them providing a tight fit. This is a somewhat extreme procedure l use for very old frames (60-70yrs) and automotive applications where it is otherwise cost prohibitive to perform a proper repair. Since parts for your situation are readily available l probably would not go that route except as a diagnostic method to see if it eliminated the problem before needlessly buying replacement parts. I would also say as a future warning that anytime you have a mating of softer metals with harder metals and a problem arises, it needs to be investigated immediately. More use only makes things worse eventually, sometimes in very short order. There are other possible creative remedies, but l don't think they apply or would have any reasonable longevity given the functional application. I forgot that I attached that diagram. It was really more for me and does not apply to your problem.