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~Any reason I shouldn't buy these [url= http://www.ebay.co.uk/itm/68052RS-aka-618052RS-Pack-of-10-Thin-Section-Ball-Bearings-6805-2RS-61805-2RS-/320927225724?pt=LH_DefaultDomain_3&hash=item4ab8c0d77c ]bearings[/url] to replace the [url= 
]knackered bearings[/url] in my shimano bb's?
I have a bearing puller already.
one good reason would be they are the wrong size 7mm wide shimano are 6mm.
ilooked for ages for the correct size shimano only? new BB . I have not thought this thro but could you use different spacers to allow for the 1mm difference?
They work fine in race face bbs but shimano use an odd size bearing. This is why I use race face bbs
not realy the secondary seals and tophats would not fit back in the cup.
okay, that's the kind of detail I was looking for.
Is there an alternative source of appropriate bearings?
Enduro sell a set but they are rubbish- worse lifespan than you'll get from a deore BB and cost more. Shimano don't lend themselves very well to this. Though, some people have happily replaced the bearing with a thicker one and "narrowed" the BB using less spacers.
An alternative might be to pick up a Gusset EXT24, which are a little more expensive than Shimano when new, but take standard bearings and are very easy to change.
yeah I've bought them from Enduroforkseals before but the exchange rate and postage makes it uneconomic now
Tried larger bearings in the shimano BB, lots of faffing and didn't run well. Just bought an Uberbike one in the end, happy easy days.
You can shave the lip and lower 1mm off the top hat edge and thus reduce the thickness and depth
The axle can then run on the existing top hats / new bearings
Alternatively get new top hats from Superstar or other places. It can be done tho - and easily. I've got a spare set of bearings if you want em to try first
I've used some of the wider ones. The top hat seal spacer thing doesn't fit as there is a lip that clips around the inner race.
I mullered mine in a bit, having first removed a 1mm spacer from the drive side. However due to my frame suiting 2x10 and me running 3x9 I needed to play around with the spacing to get the granny useable with the direct mount front mech. Was a bit of faff but all good now, and not connected to the bearing issue, but helps explain why I persevered 🙂
Been in for a few months and has been fine. I will need new top hat doofers when I come to replace the bearings next time though as they will be toast. So I'm keeping my eye on XT BB deals as they sometimes pop up for not much more than a tenner.
I wouldn't bother. Too much hassle trying to get a 7mm bearing in a Shimano BB Cup. Better to get one that takes 7mm bearings and then swap them out when you need to. Although you could get 1mm machined out of the Shimano cups and replace the top hats.
Personally I just get a Shimano BB, they're too cheap to worry about faffing about with. Which is why I've got a Hope BB. *shrugs shoulders*
Get a couple at once and XTs work out about £14 from Rose - XTR's under £20
http://www.rosebikes.co.uk/article/shimano-bottom-bracket-cups-hollowtech-ii-sm-bb70/aid:162906
This is what I'm going to try when my last spare Shimano dies. Replaceable bearings.
one good reason would be they are the wrong size 7mm wide shimano are 6mm.
yes and no, shimano are 6mm + 1mm for the external seal, so you have to find alternative top hat, like the [url= http://www.chainreactioncycles.com/race-face-x-type-bearing-cap/rp-prod39505 ]raceface [/url]ones. or you can actually file down the lip on you original shimano ones to fit but thats quite time consuming and very tedious.
a bit cheaper [url= http://www.ukbikestore.co.uk/product/386/d30062/race-face-x-type-bearing-cap.html ]here[/url]