chainsets

peter-potato said:

Why are MTB chainsets mostly 4 arm and road chainsets 5 arm?
Peter

Only guessing, but, because the chainrings are larger on road sets.

Or maybe just for tradition.

--
Jim

peter-potato said:

Why are MTB chainsets mostly 4 arm and road chainsets 5 arm?
Peter

MTB riders have trouble with big numbers.

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

Why are MTB chainsets mostly 4 arm and road chainsets 5 arm?
Peter

I had to go into the garage and look. Windcheetah and 20 year
old Rockhopper - 5. Marin Muirwoods, Revolution Cuillin and
Ridgeback Velocity - 4. Is the Rockhopper 5 arm because of its
age as I note that new ones have 4?
--
Cheers
the.Mark

In article <[email hidden]>, peter-potato
[email hidden] says...

Quoted message said:

Why are MTB chainsets mostly 4 arm and road chainsets 5 arm?

Fashion?

In news:[email hidden],
peter-potato <[email hidden]> tweaked the Babbage-Engine to tell us:

Quoted message said:

Why are MTB chainsets mostly 4 arm and road chainsets 5 arm?

110/74 5 arm chainsets were MTB standard when the world was young, but
someone (any guesses?) decided that four was better.

Or something.

--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
Ernesto, give me that Kit-Kat, or I will kill you.

peter-potato said:

Why are MTB chainsets mostly 4 arm and road chainsets 5 arm?

Sufficiently strong and stiff with 4 arms for the little diddy rings?

~PB

On 12/04/2007 19:36, peter-potato said,

Quoted message said:

Why are MTB chainsets mostly 4 arm and road chainsets 5 arm?

Just checked my bikes - both 4-arm. Oh well!

--
Paul Boyd
http://www.paul-boyd.co.uk/

peter-potato said:

Why are MTB chainsets mostly 4 arm and road chainsets 5 arm?
Peter

5 arm compact on my MTB, 5 arm standard on the Road Bike.

When I get round to sorting out a new MTB (very possibly this year given
the bendyness/creakiness of the frame), what is the recommended or
suggested BB/Chainset format to maintain some sense of future compatibility?

--
AndyM.

in message <[email hidden]>, peter-potato

(') said:

Why are MTB chainsets mostly 4 arm and road chainsets 5 arm?
Peter

Planned obsolescence. Shimano introduced the 4 arm pattern a few years ago
in one of their regular 'change things for the sake of it' campaigns, to
force people who had an old chainset that needed new rings to buy a
complete new chainset. Then they played with several different bottom
bracket interfaces, primarily for the same reason. By keeping changing the
standards they increase the amount of stock LBSs have to hold, and they
guarantee that people maintaining bikes have to spend more.

It's a marketing con, nothing else. There's no technical reason.

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

Wise man with foot in mouth use opportunity to clean toes.
;; the Worlock

"Andy" <[email hidden]> a écrit:

Quoted message said:

When I get round to sorting out a new MTB (very possibly this
year given the bendyness/creakiness of the frame), what is the
recommended or suggested BB/Chainset format to maintain
some sense of future compatibility?

I don't think this is a good time to make predictions (or purchases).

104mm/64mm 4-bolt is now the dominant chainring bolt circle format, and
looks to remain so for the moment.

External bottom bracket cups are now *de rigueur*, and a few companies have
made their cups compatible with Shimano's.

The next logical step is to change the bottom bracket shell standard and put
the bearings back inside the shell. A few manufacturers have tried this
(Cannondale in the past with their own SI format, and Scott are now making
an oversized bottom bracket shell that takes modified Shimano cups), and the
ISIS Overdrive format exists to attempt to provide an industry standard
bottom bracket shell - though nobody seems keen to adopt it.

I expect the situation will sort itself out eventually, but I thought that
about headsets. Personally, I'm sticking with square tapers until things
settle down.

James Thomson

in message <[email hidden]>, James Thomson

(') said:

"Andy" <[email hidden]> a écrit:

Quoted message said:

When I get round to sorting out a new MTB (very possibly this
year given the bendyness/creakiness of the frame), what is the
recommended or suggested BB/Chainset format to maintain
some sense of future compatibility?

I don't think this is a good time to make predictions (or purchases).

104mm/64mm 4-bolt is now the dominant chainring bolt circle format, and
looks to remain so for the moment.

External bottom bracket cups are now *de rigueur*, and a few companies
have made their cups compatible with Shimano's.

The next logical step is to change the bottom bracket shell standard and
put the bearings back inside the shell. A few manufacturers have tried
this (Cannondale in the past with their own SI format, and Scott are now
making an oversized bottom bracket shell that takes modified Shimano
cups), and the ISIS Overdrive format exists to attempt to provide an
industry standard bottom bracket shell - though nobody seems keen to
adopt it.

Actually, I think this is an area which will explode into more 'standards'
before settling down. The GBoxx standard seems to be gaining a little
traction and makes hugely more sense for mountain bikes than derailleurs.
There are now two gearboxes available, the Rohloff and a 7 speed from
another German company Universal Transmissions. Frames are available from
Nicolai, from Versus and from Brooklyn Machine Works, while GT are making
a technically similar but not GBoxx compatible bike using an adapted
Shimano Nexus gearbox. It's still expensive, and most of the bikes are
still heavy; it won't achieve much market penetration unless the price
comes down. If either SRAM or Shimano were to bring out a GBoxx-like
system, I think it could take off very rapidly.

Meantime on derailleur geared bikes we have this crazy situation where
we're putting the bearings outside the shell. That inevitably limits the
width of the bearings, and the long term solution has to be a larger
diameter BB shell with the bearings once more inside the shell. With three
companies now competing for the roadbike groupset space, we will see
innovation as they seek market differentiation. Whether we'll ever again
have a situation in which you can use pretty much any make of bottom
bracket with pretty much any frame is another question altogether.

Quoted message said:

I expect the situation will sort itself out eventually, but I thought
that about headsets. Personally, I'm sticking with square tapers until
things settle down.

M'hmm. There are some /very/ nice prices on square taper carbon chainsets
just now, says he, lustfully.

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

;; MS Windows: A thirty-two bit extension ... to a sixteen bit
;; patch to an eight bit operating system originally coded for a
;; four bit microprocessor and sold by a two-bit company that
;; can't stand one bit of competition -- anonymous

James Thomson said:

"Andy" <[email hidden]> a écrit:

Quoted message said:

When I get round to sorting out a new MTB (very possibly this
year given the bendyness/creakiness of the frame), what is the
recommended or suggested BB/Chainset format to maintain
some sense of future compatibility?

I don't think this is a good time to make predictions (or purchases).

Sadly, I think you're right.

Quoted message said:

104mm/64mm 4-bolt is now the dominant chainring bolt circle format, and
looks to remain so for the moment.

Won't dispute that, but do wonder how much longer these will remain
the 'standard'.

Quoted message said:

I expect the situation will sort itself out eventually, but I thought that
about headsets. Personally, I'm sticking with square tapers until things
settle down.

Ditto (or at least I have been till now)

I'm in a convenient position where both my MTB and Roadbike have 110mm
square taper, so I stocked up on a couple of spares which can be used
on either bike as and when required. In the worst case, if one is
totalled, I could even scrounge one from the other bike in an
emergency.

Maybe it's best to continue the theme, and only worry about 'upgrade'
when I've used up my supply of spare BB's.
--
AndyM