I just had my bottom bracket replaced on my road bike (Cervelo S3). I went for a ride and realized on the way back that the crankset was sliding right-left... That's not normal right?
Here is a video:
Thanks for the help!
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1If possible please confirm the crank set and BB brand/model.– mattnzCommented Aug 12, 2019 at 9:21
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2 Answers
That's not normal, the left/right play of the spindle needs to be removed. This is known as adding 'preload' to the bearings, so they are sandwiched between the cranks with a 'Goldilocks' force.
Look up the manual online for your specific (Rotor) crankset and you can follow their instructions so as to not miss anything out. Alternatively, if the shop did this installation recently, they will not object to sorting this issue if you take it to them to rectify.
In your video, there is the frame, and the left crank. In between the two is a knurled collar, see What is this crank part called?, which is there to take up the gap. It will have a tiny grub screw with a hex key fitting to fix its position. If this is not loosened already, it is loosened and then the collar is tightened until the point where there is no play anymore, and not any further - Goldilocks. Then tighten the grub screw to hold the position. The cranks should then turn freely with no play.
This is all done after the crank bolt is done up tight, so no need to remove the cranks, just make sure the crank bolt is (still) tight, if you want to (do this first).
Rotor have a video which seems quite clear:
There's been a problem in your situation with preloading the bearings is my guess. Based on the external bearing cup and a glimpse at the end of the video of your left crank arm, it appears you have a SRAM crankset installed? This video from SRAM, notes that insufficient preload of the bearings before full torque is reached may result in lateral play of the crankset. This is shown around the 3:30 mark of the video. While this video features a non-BBright bottom bracket shell, the similar problem to yours is fairly meaningful and if not the exact reason or answer for your case, I think it'll be along those lines.
The other video that's linked at the end of this paragraph features BBright bottom bracket and compatible FSA crankset install. Significant here is that with this particular crankset and others that mate to the BBright system, bearing seals and wave washers need to be placed and a fair amount of torque--around 45-50 N-m--is required for the fixing bolt. Missing the washer placement or less than adequate torque will lead to symptoms such as yours. BBright bottom bracket and FSA crank install
If a LBS did the BB install, it's best to return the bike to the shop and discuss it with them. The rework should incur no additional cost (IMHO).
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Sorry to downvote, but I interpret the situation differently and don't think either of the links are relevant. I believe it is a Rotor crankset with a preload collar that needs adjusting, not a GXP (first link) and not one with a wave washer (2nd link)– SwiftyCommented Aug 12, 2019 at 7:23
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2@Swifty As you wish, and agree the areas in the videos don't pertain in an exact sense as neither are Rotor cranksets. However, I note this inconsistency at the end of my first paragraph. At any rate, one needn't go beyond the first line of my answer stating the problem lies in the bearing preload, which is correct be it a Rotor or SRAM, etc crank. Given the somewhat limited info provided in the question at this time, I'm comfortable with the major point of my answer, voting be damned. (-;– JeffCommented Aug 12, 2019 at 8:02