In december I purchased a second hand Cannondale Synapse Alloy Disc 2018. It had some degree of wobble on the front chainrings from the start, but nothing major.
Recently I decided to purchase a spider based power meter (Magene P505 base), and I put on new chainrings in the same process. While installing I noticed the left BB30 bearing had some grind to it at certain points of rotation. After the installation I am able to move the crank arms laterally for about 1mm (this is at the mounting point of the pedals, so the play is less at the center/bottom bracket). Im pretty sure I've installed everything correctly. At first there was more play, but I realised I was missing a wavy washer on the non-drive side after installation of the new crank. This removed the side-to-side play, but the cranks still have some movement if I push each crank towards the center. My bottom bracket consists of two 6806 bearings pressed into the alloy frame and a 30-24mm reducer/"half cup" on each side to accomodate a 24mm spindle. I can also visually see movement of the reducer/adapter in relation to the frame when I move the cranks from side to side/laterally.
Im guessing its time to change the bearings as this will exponentially get worse?
Im also curious about these reducer adapters – is this a good solution, or should I change to a different kind of bottom bracket all together? Is it possible that the reducers are worn, and the bearings are fine? When I first need to service it, I just want to make sure that I dont renew a solution that is subpar.
If I only change the bearings. Is there a lot to be gained from purchasing a more expensive set – durability or performance wise? Or is it fine to buy a pair of FSA bearings for 20 ish $? Any suggestions for other "middle range" bearings that are sensible to put on this bike?
For the record I dont have any experience with servicing the bottom bracket, but was planning on purchasing a cheap bearing press/extractor from Ali, and doing it myself.
Thanks in advance for any input or advice!
by Dishwashertaco
2 Comments
Bb is probably out of spec and getting worse over time. See this all the time with cannondale. You can replace it but it will come back.
Yes. Replace the BB 30 bearings. The adapters are not problematic. If you want to upgrade, you can get an all-in-one conversion bottom bracket from Wheels Mfg. it is a 2 piece unit that threads together inside the frame and comes with properly spaced 24 mm bearings.