Dent in chainstay OK?

I jammed the chain of my road bike between the small chain ring and the
chainstay. As a result, there is dent about the size of half of a small
pea in the chainstay. The dent is at about 4 o'clock on a cross-section
of the chainstay viewing from the rear. The chainstay is aluminum.

I am thinking that the chainstay must be in tension, not compression,
so the dent is unlikely to lead to a failure.
Any thoughts?

Thanks,
Lew

wrote:
I jammed the chain of my road bike between the small chain ring and the=

chainstay. As a result, there is dent about the size of half of a small=

pea in the chainstay. The dent is at about 4 o'clock on a cross-section=

of the chainstay viewing from the rear. The chainstay is aluminum.
=20
I am thinking that the chainstay must be in tension, not compression,
so the dent is unlikely to lead to a failure.
Any thoughts?

The chainstay is in slight tension when you are just sitting onit,=20
greater tension when you use the rear brake, but in much stronger=20
compression when you pedal.

However this type of damage is very unlikely to cause a failure.

If it _does_ cause a failure, it won't be the sort of thing that will=20
make you crash. Worst case, it migh make you have to walk home.

I was called into diagnose a bike with a "mysterious shifting problem"=20
that had stumped several other mechanics. It shifted fine on the stand, =

but on the road, it would mysteriously "autoshift" at random times.

Turned out the right chainstay was busted in two, but the break was=20
concealed behind one of the chainrings so it wasn't easy to see. The=20
weight of the rider would pull the gap apart, but the rear shift cable=20
couldn't follow, so it would downshift by itself!

Sheldon "Inconvenience, Not Injury" Brown
+--------------------------------------------+
| If you haven=92t yet discovered the novels |
| of Neal Stephenson, don=92t wait! |
| Start with Snow Crash or Quicksilver |
+--------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

wrote:
I jammed the chain of my road bike between the small chain ring and the
chainstay. As a result, there is dent about the size of half of a small
pea in the chainstay. The dent is at about 4 o'clock on a cross-section
of the chainstay viewing from the rear. The chainstay is aluminum.

I am thinking that the chainstay must be in tension, not compression,
so the dent is unlikely to lead to a failure.
Any thoughts?

If this was a serious problem then mountain bikes would only last five
minutes ;-)

It will be fine - if you ever have the frame resprayed then you could
ask for the dent to be filled.

wrote in message
oups.com...

I am thinking that the chainstay must be in tension, not compression,
so the dent is unlikely to lead to a failure.

The RH chainstay will to some extend be compressed by the chain - and as
tensile forces (pulling?) leeds to failure rather than compression the RH
chainstay is less prone to failure than the LH chainstay. Unless the RH
chainstay is damaged, off course.

Whether the dent in your chainstay will be fatal or not is very difficult to
say. I'd say ride your bike, inspect the chainstay regularly, it won't just
snap. When cracks appear in aluminium frames they'll make noise when riding.

Wbr,
Anders

Zog The Undeniable wrote:
wrote:
I jammed the chain of my road bike between the small chain ring and
the
chainstay. As a result, there is dent about the size of half of a
small
pea in the chainstay. The dent is at about 4 o'clock on a
cross-section
of the chainstay viewing from the rear. The chainstay is aluminum.

I am thinking that the chainstay must be in tension, not
compression,
so the dent is unlikely to lead to a failure.
Any thoughts?

If this was a serious problem then mountain bikes would only last
five
minutes ;-)

It will be fine - if you ever have the frame resprayed then you could

ask for the dent to be filled.


Thanks for the replies and the good news.

Actually, I have to touch up the paint around the dent anyway. OK to
use Bondo to fill the dent?

Lew