Hi all !
Ride a Specialized Allez Sport 2010. Sora compact chainset, Hollowtech II BB.
Bike developed a nasty groaning noise, twice every crank revolution so making a noise on each pedal stroke (ie on both left and right).
Disassembled the crank and bottom bracket completely with the intention of re-greasing and re-tightening everything (including pedals). One thing I spotted once I had it out was that the bearing on the drive-side is grinding and close to seizing up. Holowtech II so it's one of those external bearing BB cup jobbies. Guess the closed cartridge seal isn't quite as sealed as it should be. It is probably something to do with riding on gritted roads this winter and then not having time to wash down properly.. A lesson learned, and 3 cans of GT85 purchased from LBS.
Anyway, these sealed cartridges can't (or shouldn't) be disassembled and serviced, so have picked up a Shimano 105 5700 BB (slight upgrade) for reasonable money from LBS.
Question is this - what effect would a ropey drive-side BB bearing have on pedalling efficiency if it was close to seizing? Will this have been robbing my back wheel of valuable watts?