Bicycle Mechanics - Is my Frame Toast?

I was cleaning up my trek and I noticed that there
is visible wear on the chainstay from being rubbed
by small chainring. The paint has been totally worn away and I can see bare metal (polished I might add). The clearance between chainring and chainstay is very tight maybe 1/8th inch as I look at it.
The frame is reynolds 531c so I know I need to seal it
to prevent rust. I'm just wondering if its toast.

Appreciate any assistance.

Marty

first of all how deep is the scrape, if it only scraped paint off it should be fine.

If the bottom bracket flexes, the clearance is probably reduced. You need a wider bottom bracket to increase clearance or it will happen again.

o yea....a longer bb would work too!:D

Take care of the problem and ride the frame until it breaks. A failure in this part of the frame is benign and will not leave you stranded. (I discovered a cracked chainstay, between the tyre and chainring clearance dimples, on my Peugeot UO-8 when I was cleaning up the BB/chainstay area in preparation for mudguard installation. I do not know how long I had been riding it in that condition.)

If you want to have preventive care given to it before a really huge repair is needed, a small patch can be silver brazed on over a worn or badly nicked area on a chainstay; I've fixed about a dozen mountain bike frames this way and none has broken yet.

Just get a new BB that's wider.....As for the nick in your chainstay, only worry if there is a visible chunk out of the metal...if it looks like its about to wear through, hang it up...but if its just a gouge I wouldn't worry...steel is strong stuff

I'm with JohnE to just ride it. I have seen a lot of bikes with bad chain cuts that just keep on going.

You can have the spot welded by a good welder and then cleaned up, if you are really concerned.

I don't thing simple brass brazing would add anything to the strength of the stay. If strength is you concern, have it welded.

From your description, however, it sounds like you are better off leaving it as it is.

Are the stays 531, or just the main triangle? How deep is the gouge?

The stays are 531c as are all other tubes on the frame.
I would say its more than a scuff and paint damage.
the entire area is 1.5 cm long by 75mm high. about 50mm square is down to bare metal,
I can't really tell about depth but there is some scoring of the metal.
What it looks like is the BB flexed enough for the
chainrings to rub the frame.
it looks like it would have to be both rings given the
length of the damaged area, but that
doesn't make sense when I think about the geometry of it.
What I'm wondering is if its rubbing that much is the frame out of
alignment so much that its unusable?
I find no discernable play in the BB itself, no sideways
movements of the cranks, the rings appear straight.
gonna bring it to LBS and see what the wrenchs have to say.
Yeah its an old bike (17 years) but I really like the
way that old steel frames ride.

Marty

Hi Lotek,

My MTB frame is fillet brazed steel and was made by the guy Rich called 'The best custom frame builder in the UK' - I'm not bragging, just preparing you for an example of 'surprisingly good value'.

If you look at this pic, you see how destroyed the drive side chain stay is caused by a duff granny ring dumping the chain several times (student budget cr@p bits). I contacted Dave Yates, the guy who built it, and the cost of replacing the chainstay and upper pannier braze-on followed by bead-blasting to the metal and a multi-coat baked on paint job and new transfers is only £134 :eek:.

It comes back tomorrow hopefully, I can't wait :).

http://www.btinternet.com/~d.b.wood/frame.jpg

I'm beginning to think a dropped chain as the culprit.
But I don't know why the chainstay would be down to bare
metal and scored.
I'm talking to a good painter about
repainting, IF they can reproduce all the correct decals.
I'm supposed to do Ride 4 Roses in 3 weeks so I don't have
alot of time to ship frame etc.
I think I'm gonna be forced to either buy build kit for
my other frame, or do a patch up job until I can get
it repaired correctly.
Hmmm I get to buy NEW stuff! thats a plus (except for the
expense) going to LBS this afternoon.