BB - any REAL advantage to hollowtech?

jimothy78

Hi all,
been thinking recently about getting new BB and crankset.

I keep reading lots of things that make me doubt the sense of "upgrading" from Squaretaper to Hollwotech. Anecdotal evidence seems to suggest that the latter is trickier to fit (requires facing of shell, etc)and more prone to wear and tear, especially in muddy conditions. I'd also have to buy a new load of tools, which is an additional expense I can do without.

The only advantages I've been able to turn up are that they're lighter (but not enough to bother me) and stiffer (does this really make a difference unless you're competing).

On the balance, then, I'm leaning towards just staying with square taper for now, unless there's something I've missed...

cooldad

IMHO - not a huge amount. Square taper will last longer. Hollowtech is easier to replace after the initial fitting, and most mid to top end cranksets are now some sort of external BB.

jimothy78

Thanks for the honest opinion - of course, I forgot to mention that I'd be looking at the lower end of the market, and yes, had noticed that there's seems to be more available ST at that end. cheers, Jim

andyk19

In my limited experience hollowtech seems to last longer, but this is little more than my experience with no more than 10 BBs. Although I should mention that I've probably been using better quality external BBs than square taper.

The Rookie

Basic Shimano ST will typically last 2500miles, most external 500 or so it seems (although maybe those are the hingers from early failure!).

cooldad

I have a 1987 bike, still on the original ST BB. So going on 25 years.
My road bike is also on it's original BB, from early 90's.
Never had an external one last more than a few years (and that's my current XTR)

jimothy78

cooldad wrote:

My road bike

LOL - it's ok, don't think anyone heard you

rhext

The square taper ones just kind of, well, keep on working! Every so often I get the upgrade bug. Then I remind myself that the current square taper one has been going for about 10,000 miles and think 'why bother'? Have to say I'm at least half-convinced that external BBs are actually a step backwards specifically designed to sell more BBs.

StorckSpeed

In the past I never really changed my bottom bracket much......I found that the ST BB shell needed changing around every 2 years, this was normally indicated by a cracking sound when pedalling. When replaced I nearly always found that the external shell had a small crack in it. As I pedalled the shell would split apart slightly and make the noise. The bearings themselves were still running smoothly.
Got the upgrade bug around 18 months and upgraded to an external BB. Since then I've had nothing but BB problems, squeeking and grinding and have gone through 4 BB's in that time.
It seems like the external bearings just don't last at all, much more prone to grit, sand and water ingress and then much more prone to wear. I've now started packing grease into the bearing to try and stop this happening, not sure if this is successful or not just yet.
They are much easier to fit and when fitted are always perfectly true, but they're around twice the price of the ST BB and I need to swap then 4 times more often.......

chez_m356

jimothy78 wrote:

cooldad wrote:

My road bike

LOL - it's ok, don't think anyone heard you

oh, but they did

chez_m356

StorckSpeed wrote:

Got the upgrade bug around 18 months and upgraded to an external BB. Since then I've had nothing but BB problems, squeeking and grinding and have gone through 4 BB's in that time.

did you have it faced ?

cooldad

chez_m356 wrote:

jimothy78 wrote:

cooldad wrote:

My road bike

LOL - it's ok, don't think anyone heard you

oh, but they did

I my defense, it's been used once in the past year, and I was a bit late - whole bunch of roadies waited - their rule is max 15 minutes. I arrived just in time, but took me a couple of minutes to get the bike out of the car. As soon as their synchronised stopwatches said 15 - they all left. Without me. Fucktards.
Except for my mate so we had a jolly good tight lycra ride together.

.blitz

Have to say I'm at least half-convinced that external BBs are actually a step backwards specifically designed to sell more BBs

The main reason is that they are quicker and easier and cheaper to fit like pretty much everything else in the MTB world that is allegedly better/stronger/faster

cooldad

This^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Erudin

I had occasional but very annoying chain unshipping due to flexing on my audax bike when it had square taper Campag triple (like this YouTube vid), none since fitting a Hollowtech chainset. As mentioned above they run very true, and don't rub the front mech or flex when sprinting.

mrmonkfinger

Completely unscientific personal experience: I've been through a few ST type cartridge bottom brackets, and I've been through one external bottom bracket. I've had external BBs for longer than cartridge.

I think having a frame that's aligned within tolerance is quite important for externals.

supersonic

Hollowtech 2 was brought about to increase the stiffness of the set up. But with existing bottom bracket shells, the cups had to be mounted outboard (to accomodate the axle), and the system requires the shell facing and preloading correctly. Square tapers were contained units and very well sealed, and they tended to last longer, but are usually heavier overall and a bit more flexy.

Now with larger shells out there, systems like PF30 can use the bearings in the shell again, but still require the facing. Interestingly, if these were thread we could have oversize cartridge BBs and cranks again...

The Spiderman

I`ve had experience with all types of bb from loose ball bearing,through square taper,external and now pressfit.
I agree that external tend to be shorter lived,but ease of fitting is much improved over square taper,and with a Deore level external bb available for a similar price to a square taper cartridge bb £15 or an XT for less than £25 the price isn`t so much an issue any more.

Decent quality square tapers aren`t as readily available these days and it limits chainset choice so personally I`d still go for an external bb despite the limited bearing life.

Correct fitting is crucial to an external bb.I wonder how many reported problems have been down to over tensioning.I know I have done it!

The problem with external is the small size of the bearings and their position whch tends to make them vulnerable to hold water.

I have managed to remove the cups,lever out the top hats and regarease them to extend their life, but I wish Shimano and co. would make them more easily user serviceable.

The pressfit is on my carbon roadbike.In theory it should be better due to the bigger bearings but it's too early to comment on durability yet.