Bottom brackets and headsets

[Tim Hall]

Being fairly averse to change, I've not kept up with the developments
in Bottom Brackets and headsets. I've tried a Favourite Search Engine
to look for a summary of what's what, but don't seem to have the right
search terms.

Can some kind soul summarise what the latest deal with bottom brackets
is - the kind with the bearing outboard - and why they're so good.
How are the bearings attached to the bike? Bear in mind I think
square tapered cranks are a New Thing.

And then a similar thing with head sets. I'm a Stronglight A9 man
myself, and have trouble even considering a threadless steerer. AIUI
integrated headsets do away with headset cups and the bearing press
directly into the headtube. Doesn't seem that smart a move to me.
What are the advantages? Or have I got it wrong (again)?



Tim

 

[Clive George]

"Tim Hall" <[email protected]> wrote in message
news:[email protected]...

> And then a similar thing with head sets. I'm a Stronglight A9 man
> myself, and have trouble even considering a threadless steerer. AIUI
> integrated headsets do away with headset cups and the bearing press
> directly into the headtube. Doesn't seem that smart a move to me.
> What are the advantages? Or have I got it wrong (again)?

Opinion is divided on integrated headsets, mostly people saying they're a
bad thing since the hole in the frame can grow and make the entire thing
sloppy. But I did rather like the fact that I could fit one without tools -
the bearing isn't pressed into the tube.

cheers,
clive

 

[Pete Biggs]

Tim Hall wrote:
> Being fairly averse to change, I've not kept up with the developments
> in Bottom Brackets and headsets. I've tried a Favourite Search Engine
> to look for a summary of what's what, but don't seem to have the right
> search terms.
>
> Can some kind soul summarise what the latest deal with bottom brackets
> is - the kind with the bearing outboard - and why they're so good.

The whole combination of cranks and bearings is claimed to be lighter and
stiffer. Drag is higher, though, apparently.

> How are the bearings attached to the bike? Bear in mind I think
> square tapered cranks are a New Thing.

Have a look at the diagrams on the manufacturers websites. Different makers
do it in different ways.

I haven't bothered to learn a lot about them yet because Campag don't make
triple versions.

> And then a similar thing with head sets. I'm a Stronglight A9 man
> myself, and have trouble even considering a threadless steerer. AIUI
> integrated headsets do away with headset cups and the bearing press
> directly into the headtube. Doesn't seem that smart a move to me.
> What are the advantages? Or have I got it wrong (again)?

Again they're supposed to save weight, also enable low stack height and neat
appearance.

There are variations, some less crazy than others.

~PB

 

[Anthony Jones]

Tim Hall wrote:
> Can some kind soul summarise what the latest deal with bottom brackets
> is - the kind with the bearing outboard - and why they're so good.
> How are the bearings attached to the bike? Bear in mind I think
> square tapered cranks are a New Thing.

The bearings screw in:

http://www.wiggle.co.uk/images/shimano da 7800 ht 2 b cups.jpg

Outboard bearings are an attempt to combine the following:

- larger diameter axle for stiffness / reduced weight
- decent size bearings (the larger axle means you can only fit tiny bearings
inside the shell, hence sticking them outboard).
- something other than a square taper interface

If you're happy with square taper I don't think there's any compelling
reason to change. Personally I never got on with square taper cranks (they
always started creaking), so I quite like the outboard bearing ones.

> And then a similar thing with head sets. I'm a Stronglight A9 man
> myself, and have trouble even considering a threadless steerer. AIUI
> integrated headsets do away with headset cups and the bearing press
> directly into the headtube. Doesn't seem that smart a move to me.
> What are the advantages? Or have I got it wrong (again)?

The main advantage is easier assembly. Here, OTOH, are some disadvantages:

http://www.chrisking.com/tech/int_headsets_explained/int_hds_explain_1.html

Anthony

 

[Simon Brooke]

in message <[email protected]>, Tim Hall
('[email protected]') wrote:

> Being fairly averse to change, I've not kept up with the developments
> in Bottom Brackets and headsets. I've tried a Favourite Search Engine
> to look for a summary of what's what, but don't seem to have the right
> search terms.
>
> Can some kind soul summarise what the latest deal with bottom brackets
> is - the kind with the bearing outboard - and why they're so good.
> How are the bearings attached to the bike? Bear in mind I think
> square tapered cranks are a New Thing.

I too think that square taper cranks are a good thing. However, there are
reasons why the new systems /may/ be better (I still use square tapers).

Firstly, the actual bearing races are further apart, which means that they
can resist the rocking action of the bottom bracket spindle better.
Second, the bearing races are larger diameter; third, the spindle is
larger diameter which means it can be stiffer with less material, and
consequently lighter.

The cups screw into the ends of a conventional bottom bracket shell (except
on some Cannondales, which have oversize BB shells). Consequently the new
systems can be fitted to conventional frames.

> And then a similar thing with head sets. I'm a Stronglight A9 man
> myself, and have trouble even considering a threadless steerer. AIUI
> integrated headsets do away with headset cups and the bearing press
> directly into the headtube. Doesn't seem that smart a move to me.
> What are the advantages? Or have I got it wrong (again)?

You're wrong. With the standard threadless headset, the head tube is just a
plain tube, and the bearing sits outside it. With newer, 'integrated'
threadless headsets, the inside of the tube is shaped to accommodate the
whole bearing inside it, but it isn't pressed in and you can disassemble
it without tools (the lower cup still has to be pressed onto the forks).

What was good about the old type over threaded headsets was just that they
were a lot simpler. The new integrated ones are neater, but aren't yet
standardised so lose some of the simplicity benefit.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; I can't work yanks out......
;; Why do they frown upon sex yet relish violence?
;; Deep Fried Lettuce

 

[Alan Braggins]

Simon Brooke wrote:
>The cups screw into the ends of a conventional bottom bracket shell (except
>on some Cannondales, which have oversize BB shells).

Cannondale are encouraging other people to adopt the same standard:
http://www.bb30standard.com/
http://www.bikebiz.co.uk/news/24323/Cannondale-wants-all-to-move-to-bigger-bottom-bracket
The "COMPANIES WHO'VE ADOPTED THE STANDARD" links page still only
lists Cannondale though.


The new Trek Madone has an oversize shell too, 90mm wide so the bearings
end up in the same place as in external cups on a standard shell, apparently.
http://www2.trekbikes.com/madone/technology/efficiency/
http://www.velonews.com/tech/report/articles/12366.0.html
http://neilroad.blogspot.com/2007/06/this-was-going-to-be-my-post-about.html


>What was good about the old type over threaded headsets was just that they
>were a lot simpler. The new integrated ones are neater, but aren't yet
>standardised so lose some of the simplicity benefit.

The Madone also has 1.5 inch lower headset bearings.
http://www2.trekbikes.com/madone/technology/strength/

Both changes seem to make some sense, but whether they will become a
new standard or be specific to one model from one manufacturer remains
to be seen.

 

[David Damerell]

Quoting Alan Braggins <[email protected]>:
>Simon Brooke wrote:
>>The cups screw into the ends of a conventional bottom bracket shell (except
>>on some Cannondales, which have oversize BB shells).
>Cannondale are encouraging other people to adopt the same standard:

Don't tell me; it's a _different_ outsize BB to the one used by BMX
one-piece cranks?
--
David Damerell <[email protected]> Kill the tomato!
Today is Second Brieday, June.