Originally Posted by
t_e_r_r_y
the dents look like really bad backpedal chain suck. i saw something similar happen to a guy's bike years ago - he was wearing baggy pants and they got caught in the chain, he tried to back pedal out of it but the chain sucked down and got all jammed between the sprockets and chain stay. he ended up having to cut his pants out of the chain and put a pretty nasty dent in the chain stay, not unlike the one on this bike.
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nomadmax did you say that the frame is made of Columbus Aelle or regular Columbus (judging from the tubing sticker)?
Most of the Guerciotti frames that we sold back in the 70's were 56cm to 60cm and they were made with Columbus SL tubing. The larger sizes were probably made with Columbus SP tubing.
Until about 1980, the Columbus SL chain stays had a wall thickness of 0.7mm. There were lots of frames made with those tubes that suffered cracks or breaks in the left - non drive side chain stays.
In 1980? Columbus increased the wall thickness of SL chain stays from 0.7mm to 0.8mm. Aelle chain stays were 0.9mm wall thickness.
A strong rider having the chain come off during a hard sprint or honking out of the saddle could have easily caused those dents when the chain jammed between the chain stay and the chain ring. Thin wall chain stays can dent easily.
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t_e_r_r_y either situation could have resulted in enough back pedaling to jam the chain.
I've had a chain bounce off and jam a number of times over 55 years of riding derailleur bikes. It shouldn't happen with a proper FD properly adjusted but it did.
I have a number of old frames with dents in the DS chain stays but they are in the center line of the tubes. It doesn't affect the ride or handling and the dents are hidden behind the chain rings.
Just one more thing.... DayGlo paint contains a high amount of pigment and requires a protective clear coat to last. It's usually been flat or low gloss. Back in the 60's a lot of US military aircraft were sprayed with DayGlo "International Orange" paint, especially for training and search and rescue uses.
High gloss clear coat could shrink a lot more when covering that high pigment content paint causing the cracking.
I have 2 frames that I built back in 1992 that I had Ed Litton spray for me using DayGlo paint with additional non fluorescent pigment. The top clear coat contained a small amount of pearlescent material.
They still look great but they're stored in a dark area to prevent fading.
verktyg
