hollowtech bearing question

polyphemus

Hi guys, been looking at Hollowtech II setups, and can't fathom out how the bearings themselves grip or lock on to the hollow tube of the spindle / axle that passes through them. After many years as an engineering fitter, I would expect some positive fixing method. Can somebody please enlighten an old geezer who'se last new bb axle came with 2 tapered cotter pins? While we're at it, what prevents lateral movement of the crankset, or is it just the spacers? All looks very clever, but a tad confusing. Looked in the search, but couldn't find anybody asking such a bleedin' obvious question!
Ta v. much for all useful input. (Gripes about non height-adjustable steering next - no, I don't get out much!!)

cooldad

They don't really grip, just a firm fit.
Lateral movement stopped by the non drive side crank.
All pretty basic, and frankly, apart from allowing a fat axle so a nice stiff set of cranks, the actual bearings are pretty rubbish compared to sealed cartridge. Lucky to last a year or so.

Steerers are another story.

IMHO all this new fangled stuff was simply to allow manufacturers to spec the same size cranks and forks to all bikes.

Mutter when I was a lad etc mutter

flappy8

+1 for them being a bit rubbish.... Have had to replace twice on my MTB after less than a year. Was persuaded by LBS to install an expensive Hope one as at least they are servicable.......

supersonic

It works like a threadless headset - an adjustment bolt pulls the cranks onto the bearings, preloading them, then the two fixing bolts hold the adjustment. When done correctly there is no play. Overtighten the adjustment though and the cranks will be too stiff.

It is paramount the bottom bracket shell faces are parallel and smooth ie faced, or their will be alignment issues and quick bearing wear.

386ka

supersonic wrote:

It is paramount the bottom bracket shell faces are parallel and smooth ie faced, or their will be alignment issues and quick bearing wear.

Tnx, i was wandering why do you need to face the shell faces. How do you know which bb shell needs facing? And is that the only reason for facing?

supersonic

You can't really see, unless has obvious irregularites. You need to put the tool to it to find out.

mrmonkfinger

flappy8 wrote:

+1 for them being a bit rubbish.... Have had to replace twice on my MTB after less than a year. Was persuaded by LBS to install an expensive Hope one as at least they are servicable.......

I've had cartridges that have needed changing after the same amount of time. It's usually down to water/grit ingress. External bearings are that much more exposed that the old cartridge type, so need better sealing. AFAIK this is where Hope's BB scores.

IMO as a heavier rider its worth a premium to get better bearings, as the cranksets seem to be stiffer. It doesn't make a great difference on the cost of a complete bike. YMMV.

flappy8

mrmonkfinger how did you know I am a heavier rider?!!!!

Unfortunately I am so we'll see how the Hopes last....