Hi,

The left side bearings on my Deore HTII bottom bracket are toast so I've been browsing around looking for the bearing code for a replacement. Just about everyone has been saying they're 6805-2RS so I bought some. It's only when you've tapped out the old ones, pressed in the new ones and they won't go all the way in that you realise Shimano's bearings are 1mm thinner.

This means the top hat won't go all the way back in so the left crank won't push all the way onto the spindle. Oddly, looking at the old bearings, they say 6805 RD and only if you google this will you get a lot of disappointed posts on forums from people who have just spent hours in the shed trying to make 6805-2RS bearings fit.

So, if you're thinking of swapping the bearings on an HTII bottom bracket, hopefully you'll see this post before you go out and buy TEN 6805 bearings like I just did.

out of the three sets of cups that I have, one is thinner than the others. 6805-2RS's fit fine in the other two sets.

you can still use them, just sand down the tiny lip on the top hat that clicks into the bearing and your done, you can even take out a bb spacer if you want the exact same axle length

Its a shame there isn't a "sticky" for this, it crops up almost every month.

On the whole for HTII LX and below use a Shimano special 61805 bearing that is 6mm thick, all the others are standard 61805 @ 7mm thick.

http://www.ukbikestore.co.uk/product/140/230_4010/fsa-bearing-cover-for-megaexo-plastic-ms148.html

These will fit to shim 25mm bearings to the 24mm that shimano use.Shame they couldn't use a5mm axle and make our lives easier