External BB's and other modern tat......

[mikesnowdon]

My mate posted on another forum about his BB being worn out. A few other people running external BB's have posted and the general idea I get is that these things are crap and wear out in a matter of months. Even the expensive ones.

I have a 1995 Hope Ti square taper BB's and its still perfect after 15 years....

Are these new fangled BB's just a fad designed to make us all buy new cranks and bottom brackets because its 'the latest thing'?

Im now thinking they must be a flawed design. Square taper internal BB's were never 'broke' so why were they 'fixed' with this new design in the first place? I reckon its all marketing. Like I-Beam saddles/seatposts. Whats wrong with rails? Nothing. I suppose Im meant to go and buy a new post and saddle now to keep up with the fashion :roll:

 

[cchris2lou]

My mate posted on another forum about his BB being worn out. A few other people running external BB's have posted and the general idea I get is that these things are crap and wear out in a matter of months. Even the expensive ones.

I have a 1995 Hope Ti square taper BB's and its still perfect after 15 years....

Are these new fangled BB's just a fad designed to make us all buy new cranks and bottom brackets because its 'the latest thing'?

Im now thinking they must be a flawed design. Square taper internal BB's were never 'broke' so why were they 'fixed' with this new design in the first place? I reckon its all marketing. Like I-Beam saddles/seatposts. Whats wrong with rails? Nothing. I suppose Im meant to go and buy a new post and saddle now to keep up with the fashion :roll:

I have an external BB on my modern ride , and I find it a lot more rigid than a square taper .

will see how long it lasts .

 

[brocklanders023]

Been running an XT external bb for 5 years and have had no problems. You need to clean them though as it's easy to get grit between the bb cup and crank arm. I guess if you don't look after them this could cause them to wear quickly?

 

[kaiser]

I've heard this too, but then again you only hear about the problems. I think the install is important. They are lighter and stiffer though so I geuss the offset may be longevity.

 

[mikesnowdon]

Good point Brocklanders.

I wouldn't know about the stifness thing, never tried it. I know thats the whole point but I dont find my Hope/Middleburn RS7 lacking in any way.

 

[mikesnowdon]

I've heard this too, but then again you only hear about the problems. I think the install is important. They are lighter and stiffer though so I geuss the offset may be longevity.

But the granks with the integral axle are heavier. In the long run theres little weight difference (in general).

The BB's have to be preoaded (like a headset) so maybe its that which causes the issue. What I mean is if there not enough preload, or too much, that could cause undue bearing wear?

 

[drystonepaul]

The idea behind external the BB is pretty sound, as it places the bearings further apart thus giving a more rigid and stable support to the cranks. The wide diameter tube instead of a narrow spindle also adds rigidity. You can definitely feel the added stiffness and it does give better power transfer.

There's also a benefit to manufacturers as an external BB will fit both 68mm and 73mm BB shells, and you don't have to worry about BB spindle lengths as it's part of the crankset.

The problem though is with the bearing seals on many external BBs. What with them being external rather than contained within the frame of course makes them much more exposed to the elements.

I've found that Deore BBs have very poor seals when compared to XT ones. My first Deore one lasted all of 3 months before the non serviceable bearing on the non-drive side seized.
However I been using a Hope stainless steel external BB on my modern P7 for the past couple of years with no problems at all.

My modern winter hack bikes run with Shimano Octalink cartridge BBs for their proven long term reliability and zero maintenance.

Don't get me started on ISIS or press fit BB30 though...

 

[marin man]

I have a hope ceramic bb and while it is very light and very stiff it is no better than my m950 xtr in octalink form,which in turn was not much stiffer than my cook bros e that I had before that,I agree that the marketing people could be robbing us blind............a bb that will last fifteen years is not in their interests is it :?:

A bit like the milk float companies,years ago there were two and one went bust as the only thing that ever wore out on them were the tyres and batteries

 

[mikesnowdon]

I hear of some people popping out the bearings and replacing them with good quality roller types.

 

[the great roberto]

I hear of some people popping out the bearings and replacing them with good quality roller types.

Yep, all for a fiver.

how to do it is here

http://www.mountainbikerides.co.uk/fett ... ement.html

A lot of external bb's fail because they are pre-loaded too much.

The mechanics of external bb's is sound, just let down by poor seals in the bearings.
Intrestingly new bikes are now coming with internal bearings press fitted .