thinking about modifying my new frame...bad idea?
 

I just picked up a late 70's Univega Gran Turismo and have some ideas in regards to messing with the frame. I was wanting to run downtube shifters that I have readily available but the bike has cable stops where the shifter bosses would be on the downtube. I was thinking about grinding off the stops and then using clamp on shifter boss where the stops used to be. Is there any reason why I can't or shouldn't do this?

Bar end shifters would be nice, but I already have the dt shifters laying around, and I will absolutely NOT use stem shifters. haha

Thoughts?

I would buy bar-end shifters. If you must clamp just clamp above or below the cable stops as necessary and leave them in place.

I am rebuilding a 1970s Schwinn Varsity for a neighbor and when I took it in to the LBS they mentioned that as an option. We ended up not doing it because even though my neighbor hates the stem shifters I can't convince him to switch to something else! However at the LBS they said they do it all the time...

No reason why you can't. May be some reasons why you shouldn't. Aside from the fact that it's a lot easier to do it than to undo it, you'll want to be extremely careful with the grinder. The downtube is highly stressed and less than one millimeter thick. Even a tiny nick (the kind that an angle grinder can make before you even know it) can result in failure. If you have to do it, I would get close with a power tool and finish with a flat single-cut hand file.

FWIW, I personally would use barcons, as that is what the bike was set up for, they will look just right, and work very well. My second choice would be as others have suggested - just clamp on the shifters above or below the existing stops. That way, when you eventually come to your senses, switching to barcons will be simple. :)

I agree I would use Barcons or even something funky like a thumbshifter.

It would look weird but I would leave the stops on and use the clampons, if they don't interfere witht he cable. Most bikes with clampon shifters had a little brazeon of some type on the bottom of the DT to help prevent the shifters from slipping.

+1 on this advice. I'd leave the frame original.

+100 You will be dropping a bomb on the bike's value. IT will look a little funky, but you could put clampon DT shifters directly above the cable stops, or just go with stem shifters or barcons.

thanks for all of the input guys. I'll try and see about using a clamp on before/after guides.

As far as value is considered, I don't have much at all into the frameset, so the bike isn't worth much as is, and if I were ever to sell it I don't think it's value would/could drop much lower than what I have into it.

Barcons would be ideal, but they cost money...haha

and stem shifters....NO NO NO. I hit my knees on them when climbing out of saddle. I gave them a shot on my 60cm panasonic dx2000. If anything it would just be worse on this 57cm frame. I would just use the bike as a single speed or fixed gear before doing that again haha.

If you are lucky, the stops would not interfere with a clamped on DT shifter, especially if they are high enough on the DT that they are mostly behind the shifter drum and out of the way of the cables.
My 1982 Peugeot PH10S had cable stops for stem shifters on it and I bought a set of clamped on Simplex retrofridtion shifters and mounted them just in front of the stops, using the stops to keep the clamp from sliding back. In my case, the shifter drum and cables did not make any contact with the stops. Only thing that contacted the stops was the back edge of the shifter's DT clamp so everything worked out well without me messing around with the cable stops at all.
I'd give that approach a try first before deciding to cut off anything from the frame.

Chombi

I'm not particularly worried about aesthetics on this bike, but do you happen to have any pictures of this setup on your bike?

buy the bar end shifter pods and flat washers from Rivendell. Use your DT shifters as barcons.

Sorry, but the bike's long gone since I traded it in in 1984.....
If you already have the clamp-on DT shifters, Just give it a try on your bike to see if it works.
Removing the DT shifter cable stops from your bike will most likely affect it's future value as people who like to use more modern equipment groups that have brifters would certainly appreciate them....

Chombi

If I read the original posters situation correctly, the frame has brazed on shifter bosses and he has a complete banded clamp on down tube shifter assembly.
Depending on the brand of the assembly I would go with shifters designed to fit the braze ons, for Campagnolo or compatible shifters cutting those apart will get you 90% of the hardware you need, only a thick washer placed inside the lever will be needed.

Way back when braze on shifters started to become the "in" thing, plenty of guys drilled out the back side of their Campagnolo shifter clamps and harvested the cable stops, only needing the mentioned thick washers to get it all to work.

brazed on?
I bet this is yet another alloy frame for the blackbullet!
come on- the barcons are a great investment, go for it.

TheBlackBullet is asking for permission to Drew? What are the penalties?

Uhhmmm......... I read his first post again and he clearly stated that "the bike has cable stops where the shifter bosses would be on the downtube.". So if I undersand correctly, it has brazed-on plain, most likely barrel shaped cable stops as commonly used on stem shifters or bar-ends, and not brazed-on shifter bosses.....

Chombi

I like this idea!

I may be just throwing around words here. I'm not honestly sure if they are welded or brazed. :p
It's nothing fancy. Butted hi-ten frame. Something I won't have to worry about when locked up using it for errands. Surprisingly not heavy for what it is. I like the paint job on it. haha

LOL
This made my day!
but yeah, that's what I'm doing. haha

this is correct

both of these ideas are better than grinding off the bosses.

OH they are at 9 and 3 oclock? Weird. I was thinging they were at like 7 and 5ish.

I had a real funky idea but if you kneeing the stem climbing it might not work for you.

If you could find it the shimano clamp for index shifters migh be wide enough to keep the barrel on the shifter from running that. But that puts the shifters pretty far up the tube.

This clamp and bases is what you need. http://www.velobase.com/ViewComponen...=104&AbsPos=19


What kind of shifters anyway? If your going friction maybe a pair of clampon top mounts.

Now I remember how it worked on my Peugeot with the DT cable stops...
http://i2.photobucket.com/albums/y44...psaaab2ce3.jpg
In the pic of the Simplex clamped on retrofriction shifters above, you see large chromed washer/metal disc just inboard of the shifter lever drums between the lever and the clamp. These discs are proud of the lever drum surface and it was the part that had direct contact with the cable stops when the shifters are clamped on. These do not turn with the levers as they act as stops (through tangs that stick out towards the front) for the lever swing when you push the lever fully forward so the levers are free to operate even when these parts are contacting the cable stops. There is a very good chance that the same will work with you frame if you use the Simplex retrofrictions or another brand of shift levers that have a similar thing going on.....as Simplex retrofrictions are now quite expensive these days.

Chombi

why dont you just pickup a set of frame mount shifters ?? it seems like a huge amount of work and danger from heat just to save 10 bucks

wow those are nice

:thumb:
That is just what I was thinking about the shipmano clampon. I am sure Bullet wants to run index so he really needs that clamp.

ultegra 600 were index and I remember them going on standard brazeons ??