Reducing friction in Shimano external BB?
I have a new Shimano external cup BB. Yes, the preload is set about right.
I would like to know if there are any suggestions to reduce the seal drag in this BB without getting a new BB instead. For example, there seems to be grease packed in between the outer dust seal and the bearings. But don't the bearings already have a seal anyway? What if I remove this grease?
I also see that Enduro sells a set of outer dust seals. Are these somehow lower friction than the stock ones?
I am also curious why it is that these dust seals are designed to slip on the OD instead of the ID.
In my experience, the Shimano external bearings feel like crap when first installed. If you check them later after some use, they are fine. Not sure why - seals need to break in, grease needs to liquify, bearings need to seat on the shaft?
I wouldn't worry about it.
It was a concern to me, too when I installed a ht2 crank. I tried thinning the grease with some lube when I serviced mine for the first time. It spinned like a cartridge bb, but I had to redo it with regular grease a few weeks later after some creek crossings.
It's normal as long as it's smooth. Spinning too freely would indicate it needs service.
What is the friction like? Can you tell a difference while riding (in the grand scheme of things?)
Can anyone actually feel this friction while pedaling? Even the super high friction GXP design feels smooth as silk to me when I'm in the saddle. Other than when I'm spinning the cranks on the bike stand, I can't feel any extra friction from external BBs.
With the chain off, if I give the cranks a hard one-finger flick, they spin around 3-4 times. On my Octalink BB, it spins like a perpetual motion device and I am able to extract free zero-point energy.
I won't make any claims about whether I can feel the extra drag or not while pedaling since it could be placebo effect.
Wow, I wouldn't worry about that at all.
First time I did a SLX crank, I took it apart and re-assembled it a bunch of times because I couldn't believe how stiff it was. It took effort to turn the crank - no spin at all. And yes, the bottom bracket was chased and faced. I Googled it and found it several posts mentioning it so just went with it.
Transferred that crank to another frame just a month or so ago and noticed at the time how much better it spun, several revolutions with a push.
Same crank and new bearings in the new frame and it's stiff again, although not as bad.
The enduo outer seals are really good....the Enduro bearings are much faster than the Shimano and last longer...
Originally Posted by beanbag
The enduro cups fit the outer seal better than the shimano cups.....
I blew through Shimano stck bearings far to quickly the Enduros last me 1.5 years.
Thanks for sharing your experience.
Originally Posted by jeffscott
So if I ONLY get the Enduro outer seals to go with my shimano stuff, will that help, or do I ALSO need to get their aluminum bearing cups?
No The Shimano has the Plastic cover...the Enduros don't the outer seal makes up the difference.
Originally Posted by beanbag
You can buy Enduro bearings that come with seals and will fit in the Shimano cup that says Do Not Disassemlbe...
A bearing puller will get the Shimano bearing out...
Carefully insert the new bearing so you don't put it out of round.
Or you can get the Enduro cups and bearings...
For that matter you can get a bearing from Boco bearing....just measure up the shaft size width and of.