Questioning Bottom Bracket installation
 

Hello everyone,

I am building my first road bike and want to be sure I have the bottom bracket installed correctly... I am installing a dura-ace BB-7700 onto a older Jack Kane custom road frame I purchased. I believe I followed the instructions correctly - the crank arms move very freely and smoothly, but there is the tiniest bit of play in the bearings (guessing) - like I didn't tighten something correctly along the way.

It also seems like the crank arms, while tightened, do not push up against the seal guards, leaving them somewhat exposed??

Any help would be greatly appreciated.

Thanks,

Mike

This is a cartridge bottom bracket, probably with radial bearings. There is no adjustment for bearing play or preload, so what you see is what you get, but some axial play is common and acceptable with radial bearings.

If the lockrings are properly tightened, you've installed it correctly.

I don't think this is accurate. The Dura Ace version of the Octalink bottom bracket is indeed adjustable and can be relubed and maintained, unlike the Ultegra (BB-6500) and 105(BB-5500) versions. A search on the Shimano Tech Document site for "BB-7700" turned up a .pdf of a Shimano tech document that describes both the installation and adjustment:

http://techdocs.shimano.com/media/te...9830646804.pdf

I stand corrected.

Unlike other cartridge BB, this one uses separate needle radial and ball thrust bearings. It allows adjustment for axial play by finding the bottom then backing off slightly. However, like other cartridges, there's no adjustment for radial baring wear.

The OP should follow the instructions and find the happiest medium between friction and play.

Thanks - I readjusted a few more times as per the instructions on the Shimano Tech Document. It seems much better now. Thanks.

Mike

There should be a slight amount of drag when properly adjusted. This is preload and necessary for bearing life.

While light preload won't hurt, it isn't necessary for this BB. The radial needle bearings are preloaded already and aren't adjustable. The ball thrust bearing will work fine without preload. The OP needs to follow Shimano's instructions and adjust for free rolling with as close to zero play as possible.