Frame alignment and tire wear question for the gurus....

[Jay Swann]

Hi All,
I've just recently built up a retro project, and have about 50 miles
on the bike. It is a Cinelli Proxima Thron frameset. I first thought
it odd when I stuck a rear wheel in the frame just after receiving it
(purchased used, of course) and with the dropout adjuster screws
approximately even, the tire was several mm's to the left of the
centerline of the BB. When i screwed in the left adjusting screw to
center the tire between the chainstays, it is significantly shorter
than the right dropout adjustment screw. No problem, I thought...
maybe just one dropout set slightly back from the other. However,
after about 50 miles, I noticed some pretty severe wear right down the
middle of the tire tread. I tried the string around the headtube to
the dropouts trick, and the measurement is within about 1/64th of
being perfect. What am I missing? The only other thing I can think
of that would cause that kind of wear is if the wheel is out of dish,
and by centering it on the BB between the chainstays, it is causing
the wheel to run canted down the road... I'm off to the garage to
check the dish on the wheel, but I tried another wheel, and got the
same results... Any thoughts as to where my problem lies? Thanks!!
--Jay

I can be contacted off list at: swann at austin dot rr dot com

[David L. Johnson]

On Mon, 18 Oct 2004 13:32:24 -0700, Jay Swann wrote:

> from the other. However, after about 50 miles, I noticed some pretty
> severe wear right down the middle of the tire tread.

IMO tire "tread" is just there to wear off, hoping to convince you to buy
new tires. Until you see the cord through the rubber, the tire is usable.

I don't see how a out-of-dish wheel can be the problem. It can only be a
few mm out of dish and still be usable, and that would cause very little
misalignment of the wheel.

Does the bike show any signs of being crashed? It may be misaligned,
which I would wonder about for the off-center wheel, not the wear. As for
that, are you used to these tires, or are they maybe less durable than
those you are used to? There is a wide range of durability of tires.

--

David L. Johnson

__o | Enron's slogan: Respect, Communication, Integrity, and
_`\(,_ | Excellence.
(_)/ (_) |

[David L. Johnson]

On Mon, 18 Oct 2004 13:32:24 -0700, Jay Swann wrote:

> from the other. However, after about 50 miles, I noticed some pretty
> severe wear right down the middle of the tire tread.

IMO tire "tread" is just there to wear off, hoping to convince you to buy
new tires. Until you see the cord through the rubber, the tire is usable.

I don't see how a out-of-dish wheel can be the problem. It can only be a
few mm out of dish and still be usable, and that would cause very little
misalignment of the wheel.

Does the bike show any signs of being crashed? It may be misaligned,
which I would wonder about for the off-center wheel, not the wear. As for
that, are you used to these tires, or are they maybe less durable than
those you are used to? There is a wide range of durability of tires.

--

David L. Johnson

__o | Enron's slogan: Respect, Communication, Integrity, and
_`\(,_ | Excellence.
(_)/ (_) |

I would suggest that you try to ride the bike no hands. This will result in
one of three outcomes:

1) The bike rides fine no hands --- everything is probably all OK
2) The bike is very difficult to ride no hands, you have to lean a lot to
make it work -- the wheel or frame is not alligned but may be salvagable
with minor adjustments
3) The bike is impossible to ride no hands -- something is really wrong

"Jay Swann" > wrote in message
m...
> Hi All,
> I've just recently built up a retro project, and have about 50 miles
> on the bike. It is a Cinelli Proxima Thron frameset. I first thought
> it odd when I stuck a rear wheel in the frame just after receiving it
> (purchased used, of course) and with the dropout adjuster screws
> approximately even, the tire was several mm's to the left of the
> centerline of the BB. When i screwed in the left adjusting screw to
> center the tire between the chainstays, it is significantly shorter
> than the right dropout adjustment screw. No problem, I thought...
> maybe just one dropout set slightly back from the other. However,
> after about 50 miles, I noticed some pretty severe wear right down the
> middle of the tire tread. I tried the string around the headtube to
> the dropouts trick, and the measurement is within about 1/64th of
> being perfect. What am I missing? The only other thing I can think
> of that would cause that kind of wear is if the wheel is out of dish,
> and by centering it on the BB between the chainstays, it is causing
> the wheel to run canted down the road... I'm off to the garage to
> check the dish on the wheel, but I tried another wheel, and got the
> same results... Any thoughts as to where my problem lies? Thanks!!
> --Jay
>
> I can be contacted off list at: swann at austin dot rr dot com

I would suggest that you try to ride the bike no hands. This will result in
one of three outcomes:

1) The bike rides fine no hands --- everything is probably all OK
2) The bike is very difficult to ride no hands, you have to lean a lot to
make it work -- the wheel or frame is not alligned but may be salvagable
with minor adjustments
3) The bike is impossible to ride no hands -- something is really wrong

"Jay Swann" > wrote in message
m...
> Hi All,
> I've just recently built up a retro project, and have about 50 miles
> on the bike. It is a Cinelli Proxima Thron frameset. I first thought
> it odd when I stuck a rear wheel in the frame just after receiving it
> (purchased used, of course) and with the dropout adjuster screws
> approximately even, the tire was several mm's to the left of the
> centerline of the BB. When i screwed in the left adjusting screw to
> center the tire between the chainstays, it is significantly shorter
> than the right dropout adjustment screw. No problem, I thought...
> maybe just one dropout set slightly back from the other. However,
> after about 50 miles, I noticed some pretty severe wear right down the
> middle of the tire tread. I tried the string around the headtube to
> the dropouts trick, and the measurement is within about 1/64th of
> being perfect. What am I missing? The only other thing I can think
> of that would cause that kind of wear is if the wheel is out of dish,
> and by centering it on the BB between the chainstays, it is causing
> the wheel to run canted down the road... I'm off to the garage to
> check the dish on the wheel, but I tried another wheel, and got the
> same results... Any thoughts as to where my problem lies? Thanks!!
> --Jay
>
> I can be contacted off list at: swann at austin dot rr dot com

[Dan Daniel]

On 18 Oct 2004 13:32:24 -0700, (Jay Swann) wrote:

>Hi All,
>I've just recently built up a retro project, and have about 50 miles
>on the bike. It is a Cinelli Proxima Thron frameset. I first thought
>it odd when I stuck a rear wheel in the frame just after receiving it
>(purchased used, of course) and with the dropout adjuster screws
>approximately even, the tire was several mm's to the left of the
>centerline of the BB. When i screwed in the left adjusting screw to
>center the tire between the chainstays, it is significantly shorter
>than the right dropout adjustment screw. No problem, I thought...
>maybe just one dropout set slightly back from the other. However,
>after about 50 miles, I noticed some pretty severe wear right down the
>middle of the tire tread. I tried the string around the headtube to
>the dropouts trick, and the measurement is within about 1/64th of
>being perfect. What am I missing? The only other thing I can think
>of that would cause that kind of wear is if the wheel is out of dish,
>and by centering it on the BB between the chainstays, it is causing
>the wheel to run canted down the road... I'm off to the garage to
>check the dish on the wheel, but I tried another wheel, and got the
>same results... Any thoughts as to where my problem lies? Thanks!!
>--Jay
>
>I can be contacted off list at: swann at austin dot rr dot com

Check the distance from the back end of each dropout to the center of
the bottom bracket and to the top center of the seat tube. A 1 mm
difference here can lead to a 3 or 4 mm offset by the time you get to
the tire.

If you don't find an easy answer, find a local frame builder and get
it checked. I had something sort of similar- the string check was fine
but the wheel had to be offset in the dropout to center it between the
chainstays, and it was canted at the brake. Basically the seat stays
had been very slightly bowed in two directions. Basic shop alignment
tricks wouldn't correct this. It took a solid alignment table and
someone with experience to correct it.

This is a used older Falcon frame, 531 throughout and I love the
geometry, so the $50 was well worth it. Again, if other things don't
do it, find a good frame builder- they'll find and fix it pretty
quickly.

[Dan Daniel]

On 18 Oct 2004 13:32:24 -0700, (Jay Swann) wrote:

>Hi All,
>I've just recently built up a retro project, and have about 50 miles
>on the bike. It is a Cinelli Proxima Thron frameset. I first thought
>it odd when I stuck a rear wheel in the frame just after receiving it
>(purchased used, of course) and with the dropout adjuster screws
>approximately even, the tire was several mm's to the left of the
>centerline of the BB. When i screwed in the left adjusting screw to
>center the tire between the chainstays, it is significantly shorter
>than the right dropout adjustment screw. No problem, I thought...
>maybe just one dropout set slightly back from the other. However,
>after about 50 miles, I noticed some pretty severe wear right down the
>middle of the tire tread. I tried the string around the headtube to
>the dropouts trick, and the measurement is within about 1/64th of
>being perfect. What am I missing? The only other thing I can think
>of that would cause that kind of wear is if the wheel is out of dish,
>and by centering it on the BB between the chainstays, it is causing
>the wheel to run canted down the road... I'm off to the garage to
>check the dish on the wheel, but I tried another wheel, and got the
>same results... Any thoughts as to where my problem lies? Thanks!!
>--Jay
>
>I can be contacted off list at: swann at austin dot rr dot com

Check the distance from the back end of each dropout to the center of
the bottom bracket and to the top center of the seat tube. A 1 mm
difference here can lead to a 3 or 4 mm offset by the time you get to
the tire.

If you don't find an easy answer, find a local frame builder and get
it checked. I had something sort of similar- the string check was fine
but the wheel had to be offset in the dropout to center it between the
chainstays, and it was canted at the brake. Basically the seat stays
had been very slightly bowed in two directions. Basic shop alignment
tricks wouldn't correct this. It took a solid alignment table and
someone with experience to correct it.

This is a used older Falcon frame, 531 throughout and I love the
geometry, so the $50 was well worth it. Again, if other things don't
do it, find a good frame builder- they'll find and fix it pretty
quickly.