[velodog]

Really? AND with bosses on the downtube as well? Because, those downtube bosses were always an important location for bar-end adapters with barrel adjusters. If you aren't going to use bar-ends, then you might as well just put them on the stem, like my 1970 Raleigh has...

No bosses on the down tube, purpose built with the shifters on the top tube. Here's a coupla pics I found on a quick search to give you an idea.

 

[PBL450]

Wow, are those custom made? I’ve never seen shifters places on the top tube, those old stem mounted shifters, sure. Where are the cables routing for the brakes? Is the shifting as clean and consistent with mounting shorter cables on the downtube? I wonder how that might impact the standover height? I guess they are forward enough not to get in the way. I wonder why this design wasn’t more common?

 

[jkc]

Old school aftermarket downtube shifter mount/clamp? Tube diameter should be the same. Leverage? Don't fix what's not broken?! It also explain the popularity of bar ends. I remember they were very finicky to use and I hated to be in the drops.

 

[velodog]

Old school aftermarket downtube shifter mount/clamp? Tube diameter should be the same. Leverage? Don't fix what's not broken?! It also explain the popularity of bar ends. I remember they were very finicky to use and I hated to be in the drops.

Top tube is typically smaller diameter than the down tube.

 

[jkc]

Top tube is typically smaller diameter than the down tube.

Depends on the tube used and very small difference if exist where it won't matter for the clamp on shifter adapter (at least the one I used when I first got into cycling and couldn't afford a proper one).

Bike Frame Design – the influence of tubing diameter and wall thickness

The usual assumption is that significant part of the ride characteristics of a frame is determined by its rigidity. An excessively flexible frame feels inefficient for power transmission and can be…

valvejob.wordpress.com

 

[velodog]

Depends on the tube used and very small difference if exist where it won't matter for the clamp on shifter adapter (at least the one I used when I first got into cycling and couldn't afford a proper one).
View attachment 482702

Bike Frame Design – the influence of tubing diameter and wall thickness

The usual assumption is that significant part of the ride characteristics of a frame is determined by its rigidity. An excessively flexible frame feels inefficient for power transmission and can be…

valvejob.wordpress.com

This is the chart that is relevant, and you can see that a standard sized TT diameter is 1/8" less than the DT. That is a significant difference and would probably mean a loose clamp.

 

[markperri666]

I just installed an ultegra 8000 rear derailler on my 1983 Trek 770 frame with an 11-speed cassette and discovered that my vintage (i.e., old, but awesome...) Campy downtube shifters have to go the full 180 degrees to negotiate all those gears. It doesn't seem to be too much trouble, for now, since you tend to be in the 0-90 degree range or the 90-180 degree range depending on the front gear, but I do have my eye on these: Dia-Compe 11 Speed Downtube Shifters. Brake-lever shifters are too expensive to experiment with and I'm not too sure I like the idea of them: they seem too easy, somehow.

 

[Openroad2014]

FD should be fine cause it does not move much. To run an older friction shifter with current 11 and 12 speed RD and cassette, cable pull is a key to be considered. also rear derailleur REAR SHIFT RATIO (Distance that rear derailleur moves laterally per 1 mm of cable movement) should also be considered. Many downtube shifters can not do 180 swing.

 

[adidman]

Thought I would give my 2 cents.. I have a 85 Peugeot psn10, I mounted a SRAM Red 11speed derailleur and a 10 speed chain onto the existing Campagnolo Victory crankset, with Campagnolo non-indexed downtube shifters, works as smooth as a top tier drivetrain does, aside from having to reach down and shift between your legs.. very soon it will have a SRAM 1x crankset with a 42 tooth ring. I just do booze-cruises mainly, just get non- indexed downshifters and call it a day.

 

[Getshifty0341]

In theory, could you mount and use downtube shifters in friction mode on modern (road) derailleurs only limited by the shifter total cable pull?

Specifically:
Dura Ace DT shifters (I believe 7700 - rated 9 speed?)
SRAM Force 22 WiFli
Shimano 11-32 Cassette

I’ve read it’s “possible” with limits and in this case, probably swapping to a 9 speed cassette.

Anyone try this and successful? Or not possible and I’d need a different/older rear derailleur?


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I know I’m a bit late to this post but was doing some research for a better derailleur than the set up I’m currently running but I felt like adding so it may help anyone else who finds this post. I have a sunrace M90 RD brand new paired with a Suntour cyclone Mark 2 FD I’m using late 70s Suntour superbe downtube shifters and my wheel set is shimano WH-RS 10 with a 10 speed cassette. I have this set up on my 1987 centurion lemans RS and I have had 0 issues with just shy of 500 road miles. I haven’t had any big climbs but as long as your downtube shifters can throw the cable the derailleur will respond. Stay safe!