Brifter conversion?
 

I purchased an early seventies Motobecane frame with bottom bracket and replacement fork with headset. I have an RX100 7 speed drivetrain I plan to install. I have spread the dropouts to accept 130mm. I am planning on possibly using a claw on the rear derailleur since the stop is too far forward on the derailleur mount. I want to attempt brifters which I know nothing about. The frame doesn't have any downtube shifter mounts. If I were to buy a downtube shifter clamp on mount and then purchase the shifter housing stops how would I know which ones will be compatible? I have been searching this information but all I could find was replacing the downtube shifters that have mounts brazed on.

Skip the brifters, and consider something like either clamp-on downtube levers or barcons.

You can get clamp-on cable stops, avoiding the need for attaching stops to a clamp-on downtube mount. This is a much cleaner solution and what I used on the UO-8, after chiseling off the single Simplex downtube shift mount.

I have downtube shifters on all my other bikes. I thought I would try something different since I have the brifters that came with the drivetrain. There are not clamp on cable adjuster type stops I assume.

The bolt on shifter housing stops have very little interface need. Specifically, the particular shape of the mounting post doesn't really matter. I expect that nearly anything you get would work as long as you have the correct size screw to attach it. I think you'll find that it's cheaper to buy clamp-on shifters than it is to buy just the clamp-on mount. For instance, you can get a set of NOS Shimano SL-434 6-speed shifters on eBay right now for $15. Buy those, put the shifters aside for some later project and you're all set.

Problem Solvers makes a downtube clamp on set of cable stops, or at least they used to...Mrs Doc has them on her Trek. While not adjustable, I so seldom need to adjust cable tension on the FD using them that you may ben able to just get along without them. Or use an inline adjuster.

7 speed indexing in general is very tolerant of cable tension, this should be an easy intro to the Wonderful World Of STI.

I can find down tube non-adjustable stops. I was unaware of inline stops.

Not inline stops, inline adjusters. Like a reverse turnbuckle for cable housing.

I misspoke, someone was talking to me while I was typing. I will check it out.

7 speed is typically 126mm spacing, no need to go to 130. I've used the old school Suntour and Shimano clamp on DT cable stops. Head to a co-op to find one. Not adjustable, but most RDs have barrel adjustable stops on them.

Crankset can be the most problematic. By the late 1970s, Motobecane LOVED Swiss threaded bottom brackets. I've seen them on anything from 1978 to 1984 Motobecanes.

I put an RX100 crankset on but the non-crank side rubbed on the bottom bracket nut. It has french right hand on both sides of the bottom bracket so I moved the adjustable side to the crankside. When I reinstalled I realized the chainrings were too far out. I just received an older Motobecane crank today but I have't seen or tried it yet.

This has really been a learning experience. The other two french bikes I got as frames only weren't so finicky. I feel a little like Homer Simpson on this one.

Gevenalle relocates shift levers onto the front of brake levers .. basic model uses friction shift-levers


https://www.gevenalle.com/product/audax/ 2 simple levers, combined.. for good reliability..

rivendell cable stops, they might be beefy enough to thread for adding the adjusters
https://cdn.shopify.com/s/files/1/14...g?v=1471028694

There's an idea!

I have a clamp-on stop like the one pictured above on my ‘86 Trek 300 Elance. I picked up the Origin8-branded version, but it appears to be the exact same part:

https://www.amazon.com/Origin8-Alloy.../dp/B00RNFTZQA

I doubt it would be practical to thread them to take barrel adjusters. I just used an in-line adjuster for my front derailleur. My rear derailleur has a barrel adjuster, so if I need to make an adjustment, I’ll just do it there.

Do you have a shop or co-op nearby? If you want to go with a clamp on downtube shifter mount with the bolt-on cable stops, then the most straightforward way to make sure everything works is to go to a shop that has both and try to fit them together.

That said, I have been running a Suntour downtube cable stop on my brifter conversion for years. Looks like this: https://goo.gl/images/4tuvCt My rear derailleur has a barrel adjuster on it and I am able to setup my front derailleur well enough to not need inline barrel adjusters. Your mileage may vary with your front derailleur (you could always add an inline barrel adjuster), but this was what I ended up with and it has worked well for me.

Regarding the older Motobecane crankset you spoke of- you may have trouble shifting older style chain rings with brifters.

No coops in my area. But I do have a few things laying around. I do have double cable stops that are not adjustable.

Then there are Kelly Take-Offs. You can adapt DT shifters to sit on stalks that extend from the side/Botom of your original Brake Levers. You will still need to find a DT cable stop or clamp band that you adapt. There are adapters that don't have cable adjuster barrels, but your Rear derailleur probably has an adjuster built in. See:
Kelly TakeOff - Kelly Bike Company : Kelly Bike Company

Those are pretty trick. So was that Gevenalle. What I am getting from all this is that maybe I can use downtube cable stops and just get the front derailleur close, not like I get out of the small chainring much, and use the barrel adjuster on the rear. Thanks for all the info and ideas!

JagWire makes in line cable adjusters, I've used them in conjunction with Origin 8 clamp on cable stops.

https://www.ebay.com/itm/JAGWIRE-BSA...EAAOSwo4pYNWMP

This is just one example they have different styles.

Another option is to modify a Huret shift lever clamp.

brifters work and worth it
 

I went to brifters (3x7, shimano tourney) using origin8 cable stops on an '80s Raleigh supercourse technium and they work very well. Adjusting the FD has to be spot on or I get an occasional dropped chain when dumping to small to fast, but the bike has become my favorite rider.

Using a chain deflector like the one linked makes triple FD setup much easier. Set it so it overshifts to the granny ring, and let the Chain Stop manage the chain.

https://www.universalcycles.com/shop...&category=1615

thanks Dfrost
 

I've never seen one of these, but it looks good. Will check my lbs/order and reports results on it. I don't dump the chain often, but when it does its always when I'm gutting up one the steeper mountain roads. The temps are going to climb into the 50s later this week. ( I just can't do the less than 45 degree stuff anymore).