In 2010 HillRider wrote:

"BTW, a weak spot on these (Klein) frames was the mounting of the downtube shifter bosses. They are not welded but held in place with a very thin threaded bolt that goes through holes in the downtube and both bosses. The thread can strip if subject to much loading and the bosses will then fall off. I've worked out a fix if it happens to your frame as it did to my son-in-laws."

I have this problem and have been looking for a solution for some time.

Perhaps someone could forward a message directly to HillRider. As a new forum member, I cannot send direct massages.

TIA

I'm sure he'll see his user name in your title and chime in soon enough. He shows up regularly.If not, I or someone else will alert him.
Meanwhile, welcome to the forum.

I PM'd Hillrider pointing him to your post. I expect he'll respond next time he's on the forum.

Hi, I'm here as requested. Sorry for the delay.

Klein had a fix kit for these frames years ago. It consisted of a pair of replacement shifter bosses mounted on curved backing plates with adhesive on the inside faces and a threaded very thin (2.3 mm) bolt long enough to go through both plates plus the down tube. Both bosses were threaded the standard M5x.8mm to fit dt shifters or cable stops bolts. One boss was drilled all the way through to clear the 2.3 mm bolt but retain the bolt head while the other was female threaded to accept the 2.3 mm bolt.

You removed the cover over the adhesive, positioned the plates over the holes in the downtube and fastened it all together with the long bolt. The head of the bolt was small enough to disappear into the clearance drilled one boss and the other end didn't come through the other boss far enough to interfere with the M5 threads.

If you wanted to use downtube shifters this kit was essential. However, these kits were rare even at the time and probably impossible to find by now. I still have one I keep as a reference but it's a museum piece

If you use STI, Ergo or barend shifters there is an easier fix that I think is much more solid and the parts are very easy to get.

All you need is the original shifter boss plates, a pair of Shimano downtube housing stops that come with every STI or barend set or were OEM on the bike, a 3-1/2" or 4" long #10-32 machine screw and a #10-32 nut.

Install as follows:

1. Drill both shifter bosses completely through with a 3/16" drill bit. This is the clearance diameter for a #10 bolt and will clear out both the M5 threads and the small holes for the 2.3 mm bolt.

2. Enlarge the holes in the downtube that the original bolt went through to 3/16" also. Do this carefully to avoid burrs in the aluminum.

3. Run the #10 bolt through one of the Shimano housing stops, then through a shifter boss, then through the frame, then through the other shifter boss, then finally through the second Shimano downtube housing stop.

4. Thread the nut over the protruding end of the bolt and snug it down to hold this whole sandwich together. Be sure the cable stops and bosses are oriented properly before tightening the nut. Tighten firmly but don't distort the aluminum downtube.

5. Saw or cut any extra bolt length almost flush with the nut and file the cut end very smooth. A drop of Loctite on the treads under the nut is a good precaution.

This is really a permanent fix and the bolt will hold the bosses and cable stops together forever. I did it on my son-in-laws bike at least 10 years ago and the repair is still absolutely solid.

I was wondering if you have any detailed pictures of this "museum piece" so that I may get ideas on how to fashion something of the sorts for my campy levers with the downtube aero shifter bosses on my '86 Klein performance.

I would love to be able to keep the system right were it is... and functional.


and hopefully my questions about how to actually feed the shifter cable to come out through the tiny hole at the bottom of the tube will be answered in other threads.

Nevermind... I am guessing from the description of the modification that this is for shifters on the sides of the downtube, and not the top of the downtube, like my setup. I apologize for not doing the research first, I just got so excited to have possibly found a semi solution to my endeavors. If anyone does have a direction to point me in, it would be much appreciated.

Yeah, my fix was based on repairing side mounted downtube cable stops. I'm not sure what your top mount looks like but I expect you could drill the top tube out for an M5 rivnut (like those use for water bottle cage bolts) and rig some way to bolt the shifter mount to it.

Or possibly convert to side mount, if there are no other ways to fix what you have. (can't picture it)
I wonder if old Cannondale side mount shifter bosses would work.

Picture:

https://s10.photobucket.com/albums/a111/all_rhetoric/project--Klein/?action=view&current=_IGP7439.jpg

Yes, drilling somewhere seems to an inevitable option, but I am still tossing ideas around in my head...

in regards to just using a tiny rivet that would fit in the existing two holes, will I run into problems finding rivets that small, and using some sort of spacer between the rivet gun and the recessed hole where I need the rivet head to stop? And obviously the third question with tiny rivets would be strength. Its a high stress area for those little guys...

I would really like to stay away from side mounts... like every other bike out there.

Your shifter mount is coming loose? This is a lot tricker than bosses. Also it would be tricky to go to any other type of shifter including bar ends because of the way the cable is routed. Good luck and report back.

I am new to this forum, so I hope this question is not out of line.

I would like to bring my Klein Performance back to original. I have the top mounted boss style shifter setup with a very poorly implemented barcon shifter conversion. Unfortunately over the years the bolt on shifter boss has dissappeared. Anyone know where I might find a replacement? Or enough information to have a new one machined?

Great forum by the way. Thanks for being here.