Dropout width

Jay Hill said:

Gary in VA said:

I've got a al mtb frame (2001 model) that the rear dropout width measures
126mm. How much damage will I do to the frame if it is spread out to
about
137mm?

Sheldon doesn't recommend it for al. From
http://www.sheldonbrown.com/gloss_sp-ss.html#spacing:

"Re-spacing is not generally feasible with aluminum, carbon fiber or
titanium frames."

So he says, but I am not aware of respacing Al frames causing many
problems in practice. Of course his experience is rather greater than
mine...but is this actual experience of problems, or just a fear that
they might occur?

The person who built one of our Al frames has already said they are
happy to respacing for us (I believe that it had already been respaced
from the standard width when I bought it). I've also ridden another Al
frame with the wrong sized hub for a year or two, but for that one the
diffference is only 5mm nominal, probably slightly less in practice. In
both cases, I suspect that the combination of force and precision
required to cold set the frame accurately is a greater problem than any
long-term weakening.

I await numerous reports of respaced frames that failed...

James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

Gary in VA said:

I've got a al mtb frame (2001 model) that the rear dropout width measures
126mm. How much damage will I do to the frame if it is spread out to about
137mm?

Sheldon doesn't recommend it for al. From
http://www.sheldonbrown.com/gloss_sp-ss.html#spacing:

"Re-spacing is not generally feasible with aluminum, carbon fiber or
titanium frames."

see also:
http://www.sheldonbrown.com/frame-spacing.html and
http://www.sheldonbrown.com/gloss_cn-z.html#coldset

the required heat treatment of Al frames does indeed suggest it's not a good
idea.
I don't think you'll get many reports as I don't think too many people would
want or be game to try it.

"James Annan" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Jay Hill said:

Gary in VA said:

I've got a al mtb frame (2001 model) that the rear dropout width

measures

Quoted message said:

Quoted message said:

Quoted message said:

126mm. How much damage will I do to the frame if it is spread out to
about
137mm?

Sheldon doesn't recommend it for al. From
http://www.sheldonbrown.com/gloss_sp-ss.html#spacing:

"Re-spacing is not generally feasible with aluminum, carbon fiber or
titanium frames."

So he says, but I am not aware of respacing Al frames causing many
problems in practice. Of course his experience is rather greater than
mine...but is this actual experience of problems, or just a fear that
they might occur?

The person who built one of our Al frames has already said they are
happy to respacing for us (I believe that it had already been respaced
from the standard width when I bought it). I've also ridden another Al
frame with the wrong sized hub for a year or two, but for that one the
diffference is only 5mm nominal, probably slightly less in practice. In
both cases, I suspect that the combination of force and precision
required to cold set the frame accurately is a greater problem than any
long-term weakening.

I await numerous reports of respaced frames that failed...

James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

Gary in VA said:

I've got a al mtb frame (2001 model) that the rear dropout width measures
126mm. How much damage will I do to the frame if it is spread out to about
137mm? I imagine that spreading the dropouts to install the wheel each time
stresses the frame and I'm guessing that riding it stressed is not good for
it either.

That's a whole lot of respacing. Half as much would be okay to just
stick the wheel in without any modification.

What model mountain bike do you have that's spaced 126mm? I'm not
sure any ever were, especially not in this millennium.
--
Rick Onanian

On Wed, 23 Jun 2004 10:52:16 GMT, "Gary in VA" <[email hidden]>

Quoted message said:

I've got a al mtb frame (2001 model) that the rear dropout width measures
126mm. How much damage will I do to the frame if it is spread out to about
137mm? I imagine that spreading the dropouts to install the wheel each time
stresses the frame and I'm guessing that riding it stressed is not good for
it either.

While going from 126mm to 130mm with an aluminum frame has worked for
me, I'd hesitate to try to reach 137mm (or even 135).

jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3

Gary in VA said:

I've got a al mtb frame (2001 model) that the rear dropout width measures
126mm. How much damage will I do to the frame if it is spread out to about
137mm? I imagine that spreading the dropouts to install the wheel each time
stresses the frame and I'm guessing that riding it stressed is not good for
it either.

MTB frames since about 1990 should all be 130mm (rare) or 135mm, so
yours is a bit weird. Anyway, no - you shouldn't stretch an Al frame
this much.

If you must have more gears then sell it and buy another bike.

Gary in VA said:

I've got a al mtb frame (2001 model) that the rear dropout width measures
126mm. How much damage will I do to the frame if it is spread out to about
137mm? I imagine that spreading the dropouts to install the wheel each time
stresses the frame and I'm guessing that riding it stressed is not good for
it either.

What frame is this? You sure you didn't measure it wrong?

MTB frames have all been 135 mm rear spacing for 15 years now, so the
fact that a 2001 model frame is 126 mm is suspect. Even road frames
have been 130 mm since 1993, when 8 speed became standard.

nick said:

the required heat treatment of Al frames does indeed suggest it's not a good
idea.
I don't think you'll get many reports as I don't think too many people would
want or be game to try it.

Aluminum frames require heat treatment after _welding_, not after
cold-setting.

It's just metal, albeit with less elongation before failure than
steel. It still bends. If the rear stays are of relatively modest
external size, you can bet that the wall thickness is generous and the
rear end will be agreeable to minor adjustment. Handlebar-thick stays
such as on older Cannondales might prove difficult simply because of
the large forces required to make them yield.

Chalo Colina

nick said:

the required heat treatment of Al frames does indeed suggest it's not a good
idea.
I don't think you'll get many reports as I don't think too many people would
want or be game to try it.

Also, stretching them this much (10mm) will put the dropouts and the
rear mech hanger quite out of parallel.

"Bill Lloyd" <[email hidden]> wrote in message > What frame is
this? You sure you didn't measure it wrong?

Quoted message said:

MTB frames have all been 135 mm rear spacing for 15 years now, so the
fact that a 2001 model frame is 126 mm is suspect. Even road frames
have been 130 mm since 1993, when 8 speed became standard.

It's a 2001 Fisher X-Caliber 29er frame that was never built up. The rear
triangle has been checked to make sure that it's still in alignment and it
is according to Fisher's specs. I'm measuring it between the dropouts where
the axles fit into them without a wheel in place. And you do have to spread
the dropouts to get a 135mm hub in place.

Gary in VA

Rick Onanian said:

What model mountain bike do you have that's spaced 126mm? I'm not
sure any ever were, especially not in this millennium.

Most if not all pre-Hyperglide MTBs were 126mm between dropouts.
There were a lot of mountain bikes made between 1981 and 1988, and
most of them have other characteristics unavailable in up-to-date
MTBs, like long chainstays and slack parallel angles, that make them
desirable even now.

Chalo Colina

Chalo said:

Rick Onanian said:

What model mountain bike do you have that's spaced 126mm? I'm not
sure any ever were, especially not in this millennium.

Most if not all pre-Hyperglide MTBs were 126mm between dropouts.
There were a lot of mountain bikes made between 1981 and 1988, and
most of them have other characteristics unavailable in up-to-date
MTBs, like long chainstays and slack parallel angles, that make them
desirable even now.

What's desirable about slack head angles? 68 degree head angles, which
were quite popular then, are fine on downhill bikes but I'm more than
happy that they're a little steeper these days.

Greg
--
Destroy your safe and happy lives
Before it is too late
The battles we fought were long and hard
Just not to be consumed by rock'n'roll

Chalo said:

There were a lot of mountain bikes made between 1981 and 1988, and
most of them have other characteristics unavailable in up-to-date
MTBs, like long chainstays and slack parallel angles, that make them
desirable even now.

I used to ride a Schwinn Cimmaron MTB that met your description -- long
stays, slack angles. I hated the handling of that thing with a passion.
So the old saw applies: YMMV.

--
Dave
dvt at psu dot edu

"nick" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

the required heat treatment of Al frames does indeed suggest it's not a good
idea.
I don't think you'll get many reports as I don't think too many people would
want or be game to try it.

It's messages like this that make me suspect that the "don't re-space
Al" advice is indeed nothing more than FUD.

James

G.T. said:

Chalo said:

There were a lot of mountain bikes made between 1981 and 1988, and
most of them have other characteristics unavailable in up-to-date
MTBs, like long chainstays and slack parallel angles, that make them
desirable even now.

What's desirable about slack head angles? 68 degree head angles, which
were quite popular then, are fine on downhill bikes but I'm more than
happy that they're a little steeper these days.

What makes those old bikes desirable today is that you can't buy such
a thing new anymore. Not everybody likes sub-70-degree angles; but
then not everybody likes the ubiquitous 71/73 geometry that is
effectively your only choice in a rigid MTB today.

If you could buy a bike with 68 degree parallel angles and 18.5" stays
at your LBS right now, then the old stuff would lose a lot of its
appeal.

As for me, I like slack angles and high BBs enough that I usually
stick longer-than-stock forks on my bikes. That lets me use manly
crank lengths and offers a hint of the in-the-groove handling
qualities I enjoy in my motorbike.

Chalo Colina