Hollowtech 2 - The Discussion

Hi,

Probably lots of us on this forum like or even love square taper BB, because they last forever and just work.

Working with Hollowtech 2, some Q's for discussion.

1) Why do Hollowtech 2 not last as long?
2) Why do the LH cup go ahead of RH cup?
3) Key question, what is a really good (in terms of life, not weight) Hollowtech 2 BB/Cup?

Or

4) does someone sell tools & have a guide for sticking in posh decent bearings like SKF into the cups...?

Cheers

Joe

JoeH":1986ye27 said:

2) Why do the LH cup go ahead of RH cup?

Click to expand...

Because being further from the chainline there is more leverage against the bearing on the left hand side.

Re:

Moving to Hope is good.

Full set of tools. But you can use on shimano

Pick
Drift
Right size sockets.
Heavy soft hammer.

Pull off seal with pick.
Knock out bearing using drift and soft hammer
Measure and order new one.
Wait and wait and wait since bearings are now in short supply.
Select socket that corresponds to outer bearing race shoulder and fits inside bb bearing housing
Apply plenty of Coppaslip to outer part of bearing
Bash in firmly with soft hammer keeping everything aligned
Replace seal
Re fit
Done

Re:

As above for removal, but rather than bash the new bearing in, use a vice and the old bearing.

Seat the new bearing by hand.

Line up old bearing on top.of new bearing and clamp in vice.

Check/realign then clamp the vice slowly until bearing is seated.

Repeat on other cup

Refit plastic bit and you should be good to go.

Imho there are a number of reasons why ht2 wear out faster:

1. Leverage. Bearings are further out than internal ones. Axles are longer too.

2. Bearings are smaller so with the extra leverage, wear faster.

3. Alignment. Internal bearings are encased in a shell within the bb. Ht2 are outboard and rely on alignment from the outer edge of the bb shell. If not flat both sides, they are out of alignment placing extra stress in the bearings. Add to that the extra leverage and smaller bearings.... having your bb shell faced helps of course, though I've never bothered.

On the plus side, you don't need to worry about the correct bb to match shell widths or axle length. Just add spacers. Which are probably another reason for premature wear as many are plastic and will inevitably compress and create mis-alignment, though potentially compensate for not quite flat bb shells.

Re:

there is a 4th and probably the main cause I've seen.
the pre load, similar problem with some cartridge hub and threaded headsets too.

you have to set the side load on them, square taper Shimano you don't, they are all nicely setup for you.

changing and service of HTII is so easy and less faff than square taper.



but just buy some, run them wear them out eventually. then worry about bearing changes.

Re:

ishaw - nice one re reminding me of vice method using old bearning. I have no bench vice at the moment and had fogotten about doing what you are recommending...

You are spot on re importance of checking to make sure everything is going in straight. Learned the hard way in the past. Bit of care and slowly slowly avoids a lot of hassle...

I've seen some axles very badly damaged too, the plating had stated to peel.

I run them but that doesnt mean I like'em!

I have GXP, Dura-Ace, Ultegra, LX and FSA cranks and they are behaving so far but the load is shared rather than the one bike doing it all.

My UN71 lasted from 1993 until 2011 and around 30,000+ miles, it even outlived a set of cranks.

The external BB have very small bearings and theres is something in the load distribution that cocks them right off - but I cant remember what I was told by an engineer with certificates and letters after his name...

JoeH":sm2d2os1 said:

3) Key question, what is a really good (in terms of life, not weight) Hollowtech 2 BB/Cup?

Click to expand...

How does Hope compare to Chris King?
https://www.hopetech.com/products/drive ... aded/#tech

https://chrisking.com/collections/threa ... readfit-24

Chris King has a lifetime warranty, but unsure on the small print details for home servicing enthusiast?

Re:

Never had a king bb but a few hope. Good quality and you can easily replace the bearings when they wear out.

Have a Hope and it’s still going strong, but at the price it is today, I’d rather just stock up on SLX when they’re on sale and chuck them when they wear. Admittedly not environmentally friendly but if you time it right you can get five for the price of one hope.

Looked at all the reasons given above for failure, but I reckon the main one is that the bearings are so damn small. Sealing is also an issue and when water/grit get in the tiny bearings can’t cope. Best replacements I had were ceramic hybrids that I used on the fat bike. Salt water killed the original Race Face set in 6 weeks, but the ceramics lasted a couple of years. Stainless cages eventually corroded but balls very fine. Only issue is that ceramic balls are more fragile, so if you’re a heavier or aggressive rider they don’t last too well. That’s why I restricted them to the fat bike.
It’s also easy to add way too much preload, you only need enough to stop play, and nip the bolts up to secure the crank. Ive seen people tighten the collar enough to hardly need the crank bolts. Should be adjusted in a similar manner to an aheadset.