Gazzza

Hi

This is my first post, i havent been able to find anything similar in the archive so i am hoping someone may be able to give me some advice.

I have a 1970's Mercier road bike, Reynolds 531 tubes, Vitus dropouts, I believe it is the 300 model. (pic 1 attached)

I purchased the bike on the internet a little while ago and have only just got all the parts together i needed. I went to start building the bicycle but while putting together the headset noticed that the steering tube was damaged. At first i thought it was the threads themselves but then noticed a slight ridge in the threads. If i poke my finger down the top of the tube i can feel a slight dent. I am assuming the bike has been in an accident at some point, maybe an impact on the handlebars and stem caused this indentation, but i just dont know for sure.

Basically when i thread the adjustable race down into place the damage causes the race to stop half a cm short of the required snug fit rendering the forks useless!

(pic 2 of damaged forks attached, damaged area is about 2 cm down on the right hand side of photo.)



Has anyone experienced this problem before? Will i need new forks, or does anyone know of a way of fixing my current forks?

Any help will be greatly appreciated.

thankyou for your time

Gareth

JohnDThompson 

That's not good. I suspect the damage is from over-tightening the stem with the stem far too high (so the expander was just barely in the steer tube). Replacing the steer tube or entire fork is probably your safest option. Is the steer tube metric thread? If so, you may have to use an unthreaded steer tube and have metric (25.0 x 1.0) threads cut onto it with a lathe if you plan on re-using the original headset. A replacement fork will likely be English thread.

Mr IGH

new fork time, otherwise, be sure your dental insurance is paid up....

HillRider

I'd try "chasing" the threads with the proper die and see if that cleans up the damage and lets the top race thread on smoothly. John may be correct and an over tight stem in the wrong place caused the damage but I'd try to clean it up first.

Gazzza

Thanks for the quick replies, would the fork be dangerous to ride then? I assumed it would be ok?

satbuilder 

As one who has been recently through this, I'll share my experience.

I have a late '70's Colnago Mexico. It was purchased about 10 years ago. Hadn't done much with it over the years except move it from place to place, due to workload, and other priorities.

The headset started getting stiff and I tore it down. I had some problems with getting the headset adjusted properly. The headset was Colnago, made by FT Bologna. As I understand it, these headsets had their problems. Small ball bearings, too.

I was also having difficulties with the threads on the steering tube. Sent it out to two different bike shops in the DC area, they wouldn't touch it, and finally sent it out to Franklin Frames in Ohio. Jack called and basically told me the threads had been chased one too many times sometime in the bicycle's life and he could repair it. Sent the fork out to him, took about a week and a few bucks, came back last week and was perfect. Serial number was still intact on the steering tube, Columbus logo was still there. He placed a sleeve in the steering tube and a new threaded section. Brazed in place, turned on a lathe to make everything concentric, good to go.

I also have a Mercier 300. Have had it since new in 1971. Although mine had Simplex dropouts. Yours may be newer.

Is this a plug for Franklin Frames? Maybe. The guy does great work. Can you find a French die block to chase those threads? I was going to get one to chase the threads on my Mexico but found out the die block cost about $150.

I don't have before and after pics, but there is a pic of the steering tube over on the framebuilding board.

If you have any questions, I'll be happy to help.

Hope this helps you,

Kurt

satbuilder 

Sorry...w\just got home from work and was lazy. Had a brew and settled down. Before I sent it out the steering tube measured less than .975 inch at the best part (left side of the pic). The right side measured about .020 inch less as I recall. Either way the threads were not suffiicient to get a positive start, or hold. I was all for trying to save the bicycle and try to preserve the historical significance. That's fine if I want to hang it up on a wall, but that's not how I operate. The only way this bicycle was going to be ridden safely was of the steering tube was repaired. So that's what I did.

Here's a before pic:



After pic:



And the Mercier. The next project....

satbuilder 

One more thing...

From Sheldon Brown's site:

Headsets
The threaded parts of a French headset are non-standard, but the press-in parts are conventional. If you have a worn-out headset, it is most likely the lower races that are damaged. If you have trouble finding a French headset, you can replace the bottom races with a standard headset, and keep the old parts on top.
French headsets use a different type of keyed washer than others. Instead of having a groove machined in the threads, the rear part of the threads is filed flat. French headsets commonly used a serrated keyed washer, with matching serrations on the threaded bearing race. This makes them slightly harder to adjust, but once they are adjusted, they hold their adjustment better than conventional designs.