polymorphself 

Building up a Motobecane Super Mirage mixte for a friend. Looking for some period appropriate cranks with a 42 to 45 tooth small ring. This will be single speed so I really only need the one. French would be cool but Japanese would be fine. Looking for one in above average shape.

bikemig 

Do you have a bottom bracket for the bike? You may want to start with the bottom bracket or find a bottom bracket with the proper threading and a matching crank.

polymorphself 

I don't, but I'll be using a newer sealed unit. A un55 or equivalent.

niliraga 

I was always under the impression that VO was the only place to find modern BBs with french threading. Have I been missing something all this time?

polymorphself 

I thought Motobecane was the only one that actually didn't use French threading, but I'm probably wrong!

due ruote 

At least your second statement is right!
Seriously, it is most likely French. Possibly Swiss.
Did any vintage Motos use British threading?

JohnDThompson 

A mid-70s Motobécane is likely to have metric (aka "French" or possibly even "Swiss") bottom bracket thread. I don't think the UN55 or other Shimano cartridges were offered with metric thread. Velo-Orange has a French thread cartridge, but if your frame turns out to have Swiss thread, you'll likely need a threadless cartridge or a Phil Wood cartridge with the appropriate mounting rings.

jdawginsc 

Here are some newer bottom bracket cups I got that work very well actually.
https://www.ebay.com/itm/New-Bottom-...AAAOSwnSxZiKpU

Finding the axle is a bit tricky though.

Last ride 76 

The price may likely be prohibitive, but I have a complete French thread phil bottom bracket in very nice condition, if you want to go that route.

nlerner

On a recent Moto project with Swiss threading, I went with a YST threadless BB. About $30. Worked just fine.

mountaindave 

You won’t know until you remove it. At least the NDS will come of the regular way no matter the size. It’s the DS cup that can be challenging. I had to examine the threads visible inside the BB to confirm I had French threading on my Gitane.

Sheldon’s BB fixed cup removal tool is your friend on a 45 year old fixed cup...

Nubra 

Thanks so much Niener! I was reading this thread becuase I was just gifted an very old Moto with cottered cranks and want to get those off. I just hope that the 116 is long enough for the cranks I hope to put on to line up the chain line.
Cheers.

polymorphself 

Ah, whoops, looks like what I had read was that they were the only ones using Swiss threading at the time rather than French. Still metric though! Thanks nlerner, that looks like it'll do.

randyjawa 

Motobecane went to standard threading in the mid seventies. This 1978 Motobecane Grand Jubilee was full standard, no French, threading. I believe the changes started in mid-1976...

due ruote 

And yet my 78 Team Champion has French bb threads and headset.

merziac

That's cause they kept using the "good" stuff on the top of the line.

verktyg 

I have 11 Motos plus 2 that I sold off. They date from 1972 to 1982.

None of them British threads... I don't recall ever seeing or working on any either. A few Motos had Swiss metric BBs with LH fixed cups.

That's not to say that like Peugeot and Gitane, they didn't start using British threads on their lower cost models in the early 80's??? Not likely in the mid 70's.

My latest Motobecane, a 1982 Team Champion:



polymorphself Like others, I suggest that you find either a crank set or a BB and then get the matching parts.

One thing to look for, Motobecane used SR Sakae Ringyo cast aluminum cotterless cranks on a lot of bikes from the mid 70's on. They can be found with the proper metric BBs too. If you can find one of these setups it would solve a lot of issues.



randyjawa You picture the headset on your 1978 Grand Jubile and said it has British threads.

Stronglight made those Motobecane badged headsets. They were good quality, equivalent to the P3 model. I have one on my 1980 Grand Jubile. plus another one in a box. They are definitely metric threaded....



verktyg

plonz 

Neither French, nor Japanese, but certainly above average and available.

https://www.bikeforums.net/classic-v...nkset-vgc.html

rustystrings61 

Stronglight made those Motobecane badged headsets. They were good quality, equivalent to the P3 model. I have one on my 1980 Grand Jubile. plus another one in a box. They are definitely metric threaded....
verktyg [/QUOTE]

I did NOT know that - but the Motobecane badged headset upper combined with a Tange Levin lower cup and crown race assembly (for where the fork was machine for a Campagnolo unit) works PERFECTLY on my Allegro that came stock with a Stronglight P3. So I got a Stronglight P3 analog built by Stronglight after all. Cool.

polymorphself 

Do you imagine the 68x110 would be a good length for single speed?

nlerner

It'll likely depend on the crankset you're going to use. Is it normally a double and you'll be using a single ring or is it made to be a single?

polymorphself 

Normally a double and using a single ring. Stronglight 93.

However, was just at a LBS and they had a look and told me I could use an English threaded BB. I was skeptical and told them it’s likely French or Swiss. The drive side went it fine, clockwise. Non drive side went in counter clockwise but is sticking out quite a lot as shown in this pic and took a bit of torque to get it this far. They assured me that this was normal. I have sealed cartridge BB’s on three other bikes. Only one of them sticks out at all and it’s about one thread. The size here is 68x103.

This can’t be normal, can it?

niliraga 

An *English* threaded BB went in *clockwise* on the drive side? whaa... ?!??

the threading is quite close, i recall, so on the NDS i could imagine that photo shows about where the ring would finally bind up.

but still, not getting my head around the DS.

polymorphself 

Sorry, opposite! Drive side went in counter clockwise, NDS clockwise.

So you would say all seems well enough? I’m just pretty confused on how an English threaded BB would work and be correct when it likely takes Swiss or french.

Here’s a slightly better angle...

Iowegian

That looks like a 73mm BB in a 68mm shell. Sometimes cartridge BB's can make it tough to get the NDS cup in without a bit of wiggling if the DS is already installed. You should be able to get either side to thread in with finger pressure or by hand with a tool if the opposing side is out.

Edit to add: with Shimano cartridge BB's sometimes the only difference between 68mm and 73mm is the NDS cup. A lot of them are marked or you can just measure the BB while it is uninstalled.