Dent in aluminum chainstay

[LegendRider]

A friend of mine crashed his Cannondale Six13 in a race last weekend. The damage consists of a small dent in the chainstay. Although I don't have a picture, I would describe it as noticeable but not severe. The aluminum is not "crinkled" it's more like a "wave" if that makes sense.

As it turns out, the local Cannondale rep was at the LBS when he brought the bike by. The rep said the frame is ruined and told him the chainstay could buckle under hard efforts. I suppose this is plausible, but does anyone have additional insights into the likelihood of this scenario?

I see plenty of people riding aluminum bikes with small dents in the top tube. But, presumably it doesn't see the stress a chainstay does. Thoughts???

[A.L.Breguet]

Cannondale offers a good deal on replacement of damaged frames.
I'd tell your bud to ckeck it out.
A second opinion from another shop you trust that is a Cannondale dealer is also a good idea.

[Fixed]

why take a chance
you have to take the good with the bad with alum
imho
cheers

[David Kirk]

Where is the dent located?

Dave

[LegendRider]

Where is the dent located?

Dave

I haven't seen it, but my friend tells me it's in the middle of the chainstay - not near the drop-outs or bottom bracket.

I'll try to post a picture tomorrow.

[David Kirk]

I haven't seen it, but my friend tells me it's in the middle of the chainstay - not near the drop-outs or bottom bracket.

I'll try to post a picture tomorrow.

Don't hold me to this but I'll bet considering the location and the small size of the dent that one could ride that thing forever without an issue.

dave

[Peter P.]

I have to agree with Dave. From your description, it sounds like the end of the crankarm flexed during the crash and dented the chainstay mid-span.

I'd say virtually all frame tubes see no stresses mid-span and therefore wouldn't impact frame longevity. It would be cause for concern if the dent were close to the tube junctions, as well as the shape of the dent.

[tuscanyswe]

Reviving this old thread since same questions. What do u guys think about something like this one? Safe to ride or time for the bin? Pity if so as its a Peg.



https://live.staticflickr.com/65535/50177674192_e730ce7c5e_b.jpg

[Dead Man]

Reviving this old thread since same questions. What do u guys think about something like this one? Safe to ride or time for the bin? Pity if so as its a Peg.



https://live.staticflickr.com/65535/50177674192_e730ce7c5e_b.jpg

ill be happy to test ride it till failure if its 53-54cm 😛

[tuscanyswe]

ill be happy to test ride it till failure if its 53-54cm 😛

Hah it is!

[gbcoupe]

Wonder what Peg wind chimes sound like?

[tuscanyswe]

Wonder what Peg wind chimes sound like?

:) beautiful n expensive?

[gbcoupe]

Hope chimes aren't the answer, but that does not look good. Maybe a sleeve could be epoxied over the damage and some length past?

Some of the frame guys here will surely chime in. Oh that was bad.

Did the wheel hook something and beat the stay?

Jokes aside, sorry about your bad luck. Hopefully can be fixed.

[tuscanyswe]

Hope chimes aren't the answer, but that does not look good. Maybe a sleeve could be epoxied over the damage and some length past?

Some of the frame guys here will surely chime in. Oh that was bad.

Did the wheel hook something and beat the stay?

Jokes aside, sorry about your bad luck. Hopefully can be fixed.

Frame is to small for me just inquiring about the severity of the dent and wether one can ride or should not. but thx.

[tuscanyswe]

Bump for those with some experience

[unterhausen]

the bottom of that dent features a sharp crease, that can't be good. It may already be cracked, possibly only on the inside.

[fignon's barber]

Steel chainstays can be replaced. If the frame has value to you, replace the stay if that's the only thing wrong with it.

[unterhausen]

But it's aluminum. That frame has a future -- as a beer can

[prototoast]

If that were my frame, I'd either send it off to someone who could replace the whole chainstay, or cut out the dent and patch it with carbon fiber.

[einreb]

Bump for those with some experience

I have a aluminum peg that cracked on the bb. In my case it made sense to weld the repair and I've ridden tons of miles with it.

Given your picture and description, I'd ride it and just keep an eye on it.

Consider cleaning up the paint and scratches at the dent (i.e. remove paint, polish, etc) so that its more obvious if some sort of crack does develop.

-Bernie

[Wattvagen]

I have a aluminum peg that cracked on the bb. In my case it made sense to weld the repair and I've ridden tons of miles with it.

Given your picture and description, I'd ride it and just keep an eye on it.

Consider cleaning up the paint and scratches at the dent (i.e. remove paint, polish, etc) so that its more obvious if some sort of crack does develop.

-Bernie

this is what i would do too. clean the excess paint out with a wire wheel and keep an eye on it.

[Tandem Rider]

Personally, I would ride it. I have broken several frames at the chainstays, in my experience, it was not a catastrophic failure in the sense that I crashed, or flames and explosions were involved. It was more a sense of "somethings odd, seems loose".

[572cv]

The first thought here was what the stresses looked like at that location, then whether any finite element analysis could show that appropriate to the location and orientation of the dent.

Sheldon Brown has a detailed piece on the early design of a Trek aluminum frame.

https://www.sheldonbrown.com/rinard/fea.htm

The location appears to be a lower stress area compared to the rest of the frame, which is good. Another question would be whether cyclical fatigue failure would come into play anytime soon. Perhaps cleaning up the area enough to put some nice matching paint on it, then watching to see if any cracks develop over time. Just two thoughts....

[tuscanyswe]

The first thought here was what the stresses looked like at that location, then whether any finite element analysis could show that appropriate to the location and orientation of the dent.

Sheldon Brown has a detailed piece on the early design of a Trek aluminum frame.

https://www.sheldonbrown.com/rinard/fea.htm

The location appears to be a lower stress area compared to the rest of the frame, which is good. Another question would be whether cyclical fatigue failure would come into play anytime soon. Perhaps cleaning up the area enough to put some nice matching paint on it, then watching to see if any cracks develop over time. Just two thoughts....

Thanks for your input guys!
Its a shame this frame cant live on with the pedigree and all but its just not worth it monetary and timewise to try and bring it back to the streets. It popped up on my pegoretti saved searches. Someday it will be a 58 in steel with no dent! :) Tho i think its only 2 of them in the last 3 years total so may still be a while.

[redir]

I would continue to ride that. Try and match up the color with some nail polish and fugetabout it.

I rode a bike like that for years.

[shankldu]

The guy is full of **** and tryin to sell u somthin point blank ive been ridin for 48 years with all sorts of dent dings in different frames THAT IS A NON ISSUE , a hairline crack on a fork or ridin on a recalled fork is where the grim reaper comes into play .

[R3awak3n]

I would not rely on my experience but I would continue to ride the crap of that frame, doesn't look too bad to me.

[Jaybee]

I have a CAAD8 with a similar size ding in the driveside chainstay. Dropped a big wrench on it, like an idiot.

Anyway, that happened in 2009, and the bike was ridden nearly daily from 09 to 2017 including some big hard rides, town line sprints, etc. with no issues and no observable change in the shape or size of the dent.

My only real issue with it is that I don't ride that frame anymore but it also has no sale value but maybe I would build it up again but probably not so it's just hanging in the garage. I dunno, maybe I could give it away for the price of shipping.

[tuscanyswe]

Yeah if it were mine and my size id likely gamble on it and continue to ride. But to buy it in this state is another story.