Fell into the trap that I gather many others have last night.

Stripped down a HTII ‘Deore’ BB (new last year) last night and replaced the bearings with std sized 6805’s and found that they are 7mm thick as opposed to the 6mm thick Shimano 6805-RD bearings.

So, first question – is it right that some Shimano HTII BB’s come with 7mm thick bearings? If so, anyone know which ones? If they are out there then I will buy some of these so in future I can replace with same thickness bearings without issue.

Secondly, for anyone that has replaced 6mm thick bearings with 7mm thick ones, what have you done to make up for the extra 2mm width? I have considered turning up a pair of 1.5mm spacers to replace to the 2.5mm spacers to account for the extra width, but then the top hat still sticks out a bit proud, which is annoying. I’ve also heard that the Shimano bearings have a relief on the inside edge which allows the top hat to snap into, so without that the axle might be a bit of a tight fit through the top hat? I’m going to have a look at that this morning.

I don’t really follow how Enduro sell one type of bearing if there are two types of cups out there (unless it’s a myth). I don’t fancy Enduro’s design though, as without the top hat, if the bearings sieze then the axle will be wearing against the steel inner race, rather than a piece of plastic.

Funny how I ran a used Saint BB for a couple of years without problem, and my other bike runs a Hone BB that is still running fine, yet this brand new last year Deore BB has lasted two wet rides! The sealing is pretty crap though, which Shimano chose to use the proper shield on the inside face of the bearing, and then a loose fitting seal the other side, trapped by the top hat. Should have just used a 2RS bearing in the first place.

All I did was to lose the flat circular seal that sat between the original bearing and the top hat. Figured that a packed 2RS bearing should be OK without that part (after all, my lower frame bearings are just sat there exposed to the world and get caked in crap as well), and so far so good. I’m using cheapo bearings too rather than SKF stuff, but they do get stripped & regreased every 3 months or so.

All I did was to lose the flat circular seal that sat between the original bearing and the top hat

But that won’t reduce the width of the BB will it? The top-hat has a shoulder on it that maintains the spacing away from the bearing regardless of whether the seal is fitted or not?

considered turning up a pair of 1.5mm spacers to replace to the 2.5mm spacers to account for the extra width

Did that, (well, made a 1.5mm and a 4mm spacer, losing 1mm each side) works fine so far. The seal fills the gap does it not, or am I remembering wrong?

Alternative is to buy a cheap HT2 BB with 7mm bearings and just reuse the cups when the original bearings die. This is what I did with my Superstar one.
TBH you can just bosh in std bearings and top hats in Shimano cups and they should be fine.

But that won’t reduce the width of the BB will it? The top-hat has a shoulder on it that maintains the spacing away from the bearing regardless of whether the seal is fitted or not?

It worked for me – with those in place the little flappy bit on the NDS crank wouldn’t drop in to the slot, without them it was fine.

The top hat does have a shoulder on it to make room for the outer seal, so ditching the seal shouldn’t make any difference to width.

I didn’t replace that seal as with it being squished against the shielded bearing I replaced the orginal with it felt pretty tight. Much better without.

Bigyinn – that is what I was asking. Is there a BB out there that definitely uses 7mm width bearings? If there is, I’ll buy one 🙂

Superstar one’s do. Shimano, none of the ones I’ve come across do, all 6mm.
Pretty sure EVERYONE else use 7mm wide bearings. Some like hope & enduro bearings dont have top hats, so the inner race has a narrower diameter.
Im hoping to try some FAG somes in my BB when the current ones fail.
Look HERE for a selection.

Cheers Bigyinn.

for now I’ll use thinner spacers and continue with the 7mm bearings in the Shimano cups – see how long they last.

I’ll try to find a suitable o-ring to take up the space between the top hat lip and the bearing. As I say, when I put the original seal back it’s nowhere near as free running. Never going to be really as the seal contacts the whole of the bearing face, but then then the top hat rotates on the inner race, so the seal gives a bit of friction.

At work we tend to use SKF, NSK or INA bearings – all decent. A cheap bearing will feel like crap straight out of the packet!!

OP remove one 2.5mm spacer from the cups you should be able to accomodate the 0.5mm?

I used superstar BB’s for a few weeks, lasted worse than deore (which has now done a winter despite feeling horrible and gritty within about 8 weeks, but hasnt developed any play despite not beign cleaned out and re-greased.

I replaced the superstar brearings with INA ones, time will tell whether they last longer than anything else. So far they’ve doen a week in Spain and 3 months at the start of winter and still feel fine.

Race face also use standard bearings and are shimano compatible.

Acros make BB’s, cost as much as hope though so not a cheep option.

Cynic-al – yeah, I doubt the .5mm will make a difference, but being a little anal and having access to a lathe means I’d be just as happy to make a 1.5mm spacer and a 4mm spacer – that way it’s 1mm off either side 🙂

What about removing 1mm off the shoulder inside the Shimano cup to accommodate the wider bearing?

just knackered my LX/XT BB up on the Mendips this morning. Have a brand new spare here so will have a go at fitting some decent 7mm bearings myself if I can’t sort the bearings.

SS cups and decent bearings works well for me.

If you want to go down the repacking bearings route, the wee spring from an old set of brake pads is a great seal prising tool.

Bigyinn, that was the other option. Looks like there is plenty of meat to do so.

I’ve gone with a 1.5mm and 4mm spacer for now. Should be fine. As I said I’ve left the outer seal out as it rubbed too much, silky smooth with the new bearings and top hats. Hopefully the bearing shields will do their jobs (after all, most pivot bearings are open to the elements), and if they don’t I’ll replace them 🙂