Hey guys, curious on your opinion about this. I have a 105 crankset I want to use on a 1970's Peugeot frame. What I am thinking I might be able to do is have both sides tapped to an english right hand thread and use two non drive side bottom brackets with a spacer on the drive side. Because there is no adjustable cup in this setup I think it might work.

Would this be a feasible option? Apologies if this has been posted but I couldn't find the answer anywhere and want a second (or multiple second opinions) before I proceed.

Cheers

This idea may just be the fastest way to strip a bottom bracket shell. BSA thread are slightly smaller than 35mm, so you start with a sloppy fit. Then the pitch error between 25.4 tpi (1mm pitch) and 24tpi ensures that the tap will be shaving the sides of the thread profile, and the threads will be 180° degrees out of phase over the span of about 3/8 inches.

The only way to convert a French BB to BSC is to fill the threads with braze, then ream and tap fresh. Of course that means burning off all the paint for about 6" in every direction.

An English bottom bracket has a diameter of 1.37 inches, or about 34.75 mm -- about a quarter millimeter smaller than a French bottom bracket shell. I'm afraid there might not be enough thread depth after tapping to securely hold an English bottom bracket.

Tapping to Italian might make more sense. Italian bottom brackets are 1 mm bigger than French. You'd just have to account for the difference in shell width. French bottom brackets are 68 mm and Italian ones are 70, so you'd need a 1 mm spacer on each side. Would this work for your particular crankset? I don't know and would have to defer to someone who knows Shimano two-piece cranks better than I do. (Is the spindle the same length for English and Italian? Are the cups the same depth?)

https://www.philwood.com/products/bbpages/1gsobb.php

I know that, I'm just not super familiar with the retapping process, what I was hoping is since it was Hallowtech II that the threads weren't utilized all that much for stability of the crankset (and hoping that I might just be able to use some locktite), I am aware of the Italian solution, but am having trouble finding a shop in Toronto to do it. Their resounding response is usually, "have you looked at this Giant bike?" I mostly want to keep the frame because I like how it rides, but the cottered crankset is no longer serviceable.

Do you know how much tapping to Italian would cost? Because I do know the Shimano makes an Italian bottom bracket to compete with Campy.

Possibly a stupid question, but is Phil Wood bottom bracket compatible with Shimano cranksets? It's a pricey solution, but one that could work really well.

Not a stupid question! I didn't know Phil did outboard bearings. (I don't have any two-piece cranks, so haven't needed to keep up on what's available.) Based on what I'm reading elsewhere online, Phil makes a French-threaded stainless steel outboard bearing cup and you should be able to make it work with a Shimano Hollowtech II crankset. I'd suggest not taking my word for it and contacting Phil Wood for details.

Except for going the fill and retap to English or tap oversize to Italian route, Phil Wood seems to be your only choice. If the frame is worth the investment, that has to be the way to go from an overall cost and not having to repaint. Contact PW for conformation but I'd be absolutely amazed if their cups are't Shimano compatible.

The paint isn't a big deal to me as I will be repainting, or powder coating the frame and applying some vintage decals. I'm thinking from an ongoing cost perspective it might be better just to tap to Italian and use spacers. The Phil Wood stuff is nice, but much pricier than I thought, and requires special dust caps. Plus I'd have to figure out where to buy it. I'll message him, but I'm assuming the bottom bracket cost more than the crankset I have lying around.

I've found solutions for most of the other issues I'm having, Velo Orange makes a French Headset and another company makes a French quill stem adapter so I can use modern alloy bars which is nice. As for the derailleur hanger I still need to find a solution for that. Anyone have any suggestions about where I could get a hold of one? I kept the old Simplex hanger and was thinking I might just be able to replace the rear nut?

Indeed. Bicycle Research used to offer a reamer/Italian tap set for exactly this purpose:



Perhaps a shop or co-op local tp the OP may have this?

Which version of Simplex dropout do you have? The old, unthreaded 9mm hanger can be tapped to take a 10mm threaded derailleur mounting bolt, but you may need to file a stop tab to hold the derailleur body in the proper orientation. Otherwise, Simplex derailleurs that would work without any dropout modification can still be found on e.g. eBay. Later Simplex dropouts were threaded and incorporated stop tabs to accommodate non-Simplex derailleurs:

Tapping to Italian and using a Shimano Hollowtech II bottom bracket (readily available in Italian threading) is the route I'd use. In fact, I may do this with a 1970s Peugeot that needs to be rebuilt.

Why not just get a french-threaded square taper BB and a decent square taper crankset? Seems a lot easier than kludging a vintage frame.

I have the 105 groupset so I kind of want to use it on a bike finally, the frame has great geometry... But needs to be updated for what I want it to do. It is not really a restoration quality frame. A lot of the smaller brazeons (sp?) are damaged and will be filed away, so it makes more sense to me to update it to a current standard where needed.

...some co-ops have Italian BB taps ( ours does, I bought them myself) but it's anybody's guess depending on where you live.

A lot of the actual, for profit bike shops are not real interested in doing this sort of stuff any more; too time consuming for the rewards. If you have a frame maker within reasonable distance, that might be your best bet, but basically you are gonna have to do some calling around if you want to do the ream and tap to Italian thing. I'm still looking for a fixed reamer tool to do this, but we'll probably have to continue using an adjustable one, with the hazards that can entail.

...BTW, most of the quill stem from French to modern are most cheaply and easily accomplished by slowly and carefully sanding off .2 mm from the diameter of your chosen modern 22.2 stem.

It goes pretty quickly, because aluminum, so make sure you measure with a caliper regularly during the process, and test fit occasionally.

Would said co-op by chance be in Toronto? I know that bike shops want to sell me stuff... It's why I always feel like calling BS on this whole "LBS" concept. They're mostly all the same, show rooms for large bike brands.

I do have a frame maker near by ish, but they're still an hour away by car. And I have no way to get there. As for the stem... I want to replace it altogether, I thought I might be able to braze in a new stearer, but the adapter would be a happy medium for me. I have no issue with the quill part of quill stems. I dislike the limited selection of bars I can use with the stem.

I could do a lot of this stuff myself, I have built a frame before, but I lack the taps and equipment to face the bottom bracket shell. I had a frame builder do that for me.

This doesn't apply here. Your Peugeot is low end and uses a claw hanger. Any RD with a claw will work. The Simplex claw won't work with anything but some Simplex derailers.

I doubt if you will be able to use much of your 105 group on that frame. The headset and seat post won't fit. The brakes almost cetainly don't have enough reach. A Phil Wood BB or even tapping the BB wil cost more than the frame is worth. I'd look for a more appropriate frame.

... Yes it is a claw hanger, called a bike coop this morning a retap will cost about $40. I'm using the frame because I like how it rides, I salvaged the group set from a bike I found in a dumpster. Brakes do have enough reach, not really attached to the headset. More than anything it's a make work project