I have a Trek Emonda which has a T47 bottom bracket. A carbon bike with a threaded aluminium sleeve bonded into it. I love the bike but have had nothing but problems with the BB
After a year of riding, I started to get a clicking sound when putting power down. After disassembly the LBS found that the bonding had failed and the sleeve had damaged the frame. Trek did a warranty replacement, no questions asked.
After 6 months of riding the new frame, it also started developing an annoying clicking in the BB area. This time the carbon wasn't damaged and the problem went away with a standard BB regrease and service... until 6 months later. The bike shop said this isn't that unusual and is somewhat expected for a performance bike?
I have mountain bikes which have taken far worse all-weather thrashing and their BSA BBs have had no problems. This T47 standard was supposed to solve the issue of creaking in carbon frames, but has actually creaked more than any other standard I've owned.
Looking further, it seems quite a few Emonda owners have had this problem (and the bike is now discontinued in favour of Madone, which also uses T47) and not many brands other than Trek seem to have jumped on the T47 bandwagon. Is it just a bad standard, or a bad bike, or have I been unlucky?
In future I would buy a nice steel or alloy bike with BSA BB, no proprietary parts and no full headset routing.
T47 is just an oversized version of BSA to better accommodate Dub/30mm axles. There are no 'bad' standards - there is poor manufacturing, poor fitting/maintenance or poor matching of crank to BB (oversized axle in a shell designed for 24mm). It sounds like poor manufacturing on the part of Trek tbh, which unfortunately is harder to fix with a threaded BB!
T47 is just an oversized version of BSA to better accommodate Dub/30mm axles. There are no 'bad' standards - there is poor manufacturing, poor fitting/maintenance or poor matching of crank to BB (oversized axle in a shell designed for 24mm). It sounds like poor manufacturing on the part of Trek tbh, which unfortunately is harder to fix with a threaded BB!
Got it - in this case it's for a 24mm Shimano axle so I'm not even sure why it needs to be oversized. If manufacturing tolerances is the key issue, it seems like T47 is just as worse as Pressfit, if not more so. So I don't understand how it's been touted as a solution.
I have had a similar issue with my ti frame.
Short version: I found believe it or not that some BBs fit better than others. There was literally play when screwing in.
Hope and Rotor. Play that led to clicking.
Praxis no play when screwing in.
No idea why - I guess manufacturers tolerances probably on the bike? I tried lots of things like plumbers tape.Â
Anti-sieze helped too. But ultimately it was about finding a bottom bracket that was a tighter fit.
T47 is just an oversized version of BSA to better accommodate Dub/30mm axles. There are no 'bad' standards - there is poor manufacturing, poor fitting/maintenance or poor matching of crank to BB (oversized axle in a shell designed for 24mm). It sounds like poor manufacturing on the part of Trek tbh, which unfortunately is harder to fix with a threaded BB!
Got it - in this case it's for a 24mm Shimano axle so I'm not even sure why it needs to be oversized. If manufacturing tolerances is the key issue, it seems like T47 is just as worse as Pressfit, if not more so. So I don't understand how it's been touted as a solution.
Part of the solution is that it's much easier to manufacturer correctly, at the expense of a bit of weight. When I was building up a new road bike recently I discounted anything that wasn't T47, and from research, problems on the budget Chinese frames with it appear to be limited to the threads occasionally needing chasing.