I have a BMC bike (Roadracer SL01) and I have just switched out the Ultegra 6750 crankset to install a new power meter. I have the following installed:
Power2Max type S
Rotor 3D+ cranks
new Rotor BSA30 BB
Praxis Works Mid-Compact chainrings (I was on compact Shimano Ultegra before)
New Shimano chain and Shimano rear cassette (12-25)
The problem I now have is a lot of noise which I have narrowed down to the chainline not being correct. It is like the drive side crank/chainrings are not near enough to the frame (even though it is in as far as it goes and the Rotor pre-load bolt is tight on the non-drive side).
For example, in the small chainring, largest two rear cogs I get rubbing sound when the chain comes over the chainring as the angle is quite acute. I would expect this for cross chaining but not for this combination. The chain is not touching the front deraileur. If I use the trim function on the deraileur to shift the chain to the right slightly, the noise is reduced.
Is this normal to do this with the chain in the lowest gear? Should I even setup the front deraileur so that is pushing the chain in all the time (seems like a bad idea). Or will the problem go away when the chain/rings wear in?
I also thought about alternative bottom brackets that could be a lesser width but didn’t have any joy finding anything alternative.
Thanks for your help as I’m at a bit of a loss on this one!
I have a BMC bike (Roadracer SL01) and I have just switched out the Ultegra 6750 crankset to install a new power meter. I have the following installed:
Power2Max type S
Rotor 3D+ cranks
new Rotor BSA30 BB
Praxis Works Mid-Compact chainrings (I was on compact Shimano Ultegra before)
New Shimano chain and Shimano rear cassette (12-25)
The problem I now have is a lot of noise which I have narrowed down to the chainline not being correct. It is like the drive side crank/chainrings are not near enough to the frame (even though it is in as far as it goes and the Rotor pre-load bolt is tight on the non-drive side).
For example, in the small chainring, largest two rear cogs I get rubbing sound when the chain comes over the chainring as the angle is quite acute. I would expect this for cross chaining but not for this combination. The chain is not touching the front deraileur. If I use the trim function on the deraileur to shift the chain to the right slightly, the noise is reduced.
Is this normal to do this with the chain in the lowest gear? Should I even setup the front deraileur so that is pushing the chain in all the time (seems like a bad idea). Or will the problem go away when the chain/rings wear in?
I also thought about alternative bottom brackets that could be a lesser width but didn’t have any joy finding anything alternative.
Thanks for your help as I’m at a bit of a loss on this one!
Regards
Richard
First, a picture of what you are talking about would help so much…
Next, exactly what is it rubbing on while on the inner ring using the two largest cogs in the back? Is it the outer chainring? If it is then you are missing some spacers on the drive side between the BB and the crank.
Now I just eyeball a chainline while setting up a bike and have only had to fine tune that once. I look straight down from the big chainring and line it up with the middle of the rear cogs. Is yours like that? Further in/out?
Attached are a couple of images, first is with the derailier not trimmed and secondly trimmed, so it pushes the chain outwards slightly. The noise is a clicking sound where I think the chain meets the inner chainring at an angle. I don’t get the issue on the outer chainring. The third picture is from the rear.
I was originally thinking the chainrings were to far out from the frame, but taking these pictures and your comment re-spacers makes me think I could have this wrong and actually I need to put in spacers to bring the chainrings out from the frame?
Thanks
Richard
No trim -
Trimmed (front derailer pushes chain outwards slight - you get chain run but not the clicking) -
From rear - front derailier fully inwards, not trimmed
It looks to me like the chain is rubbing on your front derailleur. The chainline looks to be spaced out just a little too far but not abnormally, the opposite of what I said earlier.
I would investigate the cable to see if it is hanging up, then inspect the derailleur to see if it is hanging up. If that is all good then I’d loosen the inner limit screw to the point where it stops rubbing and then check to see if the chain drops while shifting from big to little.
I would also investigate the outer limit of the derailleur as well.
If it is in fact a chain rubbing issue then you’re all good. If it still makes noise then some more investigation is in order.
It definately isn’t catching on the front derailleur - I cross checked by removing the cable entirely and slacking off the low screw. Still get the same clicking noises.
I also took off the drive side crank and inserted the two small nylon spacers (about 1mm each). I get the same issue but can’t setup the front detailleur in this case to shift to the outer chain ring, so presume they are too far out in this case and I don’t need the spacers?
Thanks. I’m not sure as I can’t see the chain anywhere near the derailleur. It seems to be clicking over the small chainring either pedalling forwards or backwards. I can’t get the chainrings any closer to the bike.
wtf is on the non-drive side between cranks and BSA30 bb? when I used a bsa30 bb in the past, there were no spacers on either side. it works like a standard bb with the rotor(or quarq) bb30 cranks. rings are way too far out from bike. normally large ring should just cleat chainstay by 3-4 mm, looks like you have 15mm.
but you are not installing these as a bb30 set up, you are using the bsa30 bb which acts like a bb24 for the bb30s, ie there should be no preload(non drive) and no 11.5 spacer(drive) if you have those on, I am not even sure how you are keeping the cranks on with so few threads likely engaged
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Yes, I’m installing into BSA30 BB - no spacers on drive side, only pre-load nut on non-drive side. I checked the 3d+ installation instructions and it doesn’t say not to use the pre-load nut. To clarify, are you saying I DON’T need the pre-load nut for BSA30 BB? I can take it off and see what that result that gives
Okay, I tried without the pre-load bolt and it doesn’t make a different - same issue. I think the pre-load bolt must be needed as I wouldn’t have expected exposed thread like this without it - looks like it is expected to be there:
I’ve just been speaking to Rotor and they confirmed the non-drive side preload bolt is need and suggested I try without the bearing seal on the drive side to try and bring the chainrings in closer. I tried that but unfortunately didn’t resolve the issue. I’ve not really got any more options adjustment wise on the cranks.
I have seen instances where people buy secondhand cranks from Cervelos that have the “BBRight” lock ring (the bottom one) which pushes the drive side out 11.5mm and looks just like what you have going on. Not the case if everything came from P2M.
Something is going on that your drive side is pushed out too far. I have two of those cranks, a P2M, and a BMC and the incorrect lock ring is the only thing I can think of. That doesn’t appear to be the case here if you have the narrow lock ring.
Can you get a pic of the inside of the spider and another one of the bottom bracket on the drive side? Something is going on to push that crank out.
JaretJ and jeffp always give out solid technical advice and I’m joining them in scratching my head.
The only other advice I can give is that your saddle is too high.
Thanks for all help folks, it’s really appreciated as I’m scratching my head also!
I don’t think it will be the saddle as I get the problem when turning the pedals when riding or by hand. The video I shot earlier my me turning by hand.
I’m just about to upload some photo’s once they have downloaded from my phone and before it gets dark here in the UK.
