motobecane conversion
 

Long time lurker, first time caller. I bought a Motobecane Nomade Sprint recently for conversion w/o realizing the problems w/ bottom bracket threading, stem, headset etc. Is there anyway for me to convert this on the cheap? Or should I scrap it and try to pick up something more traditional? I need a beater to commute to work this summer. Thanks.

You can use all of those original parts, so your biggest worry is the rear wheel and chainline.

If in case you want to part it out later, I could use the bars / stem...

I think the rear wheel is shot. It keeps slipping out of gear when I ride it. Also, it should be known that I'm pretty much a novice at bike mechanics. I figured I could convert this relatively easy, but the more I look at it the more it looks like a money pit.

i absolutely love french bicycles. you should too.

bottom bracket -- if there is a functional bottom bracket on the bike currently, keep it. you should be able to adjust chainline either via spacers on the bracket itself or with spacers/putting your chainring on the inside. also, depending on the cups that are on the bottom bracket currently, you may be able to buy another, shorter, spindle to accomodate whichever cranks you want... example... i have sugino french threaded cups and have a sugino 75 njs spindle that i use with it... for my sugino 75 cranks.

headset and stem -- if the headset included is in good shape, keep it. my gitane has a stronglight competition headset that works like a dream after some new bearings and a lot of phil wood grease. of course, with an original headset and fork, you are possibly stuck with the 22.0mm instead of the standard 22.2mm steering column.... as sheldon brown has pointed out, sometimes the fork itself is 22.2 and you sand down the headset rings.. if that doesn't work, it isn't that much work to sand down a stem to fit. you will likely not suffer much aesthetically if you finish with a fine-grit sandpaper and only sand up to your insertion point. it took me 30 minutes while watching an episode of the O.C. that bike you see in my avatar is french -- that cinelli stem is sanded way down.

now, if the headset is a total piece of crap -- or if you simply want to replace it, get the stronglight A9 M25x100 (french threaded) headset. they still make it -- it uses nice needle bearings and is the smoothest french threaded headset that you can find. www.xxcycle.com has it for $24.79 + $10 shipping to the united states ... this is WELL under what harriscyclery charges here in the states. with the A9, assuming that your fork steerer is indeed 22.2, you will have no problems with stems. of course, it might be 22.0 and you'll still need to sand.

you should do the conversion.. it's fun.

(reply to OP)

Money pit -

Not really. Right now, you have to decide if you will spend money on labor or tools. Ultra cheap is single speed it by losing all derailers, and picking the front / back sprocket combo that suits you, and string the chain to keep it as straight as possible. On a double, that's usually the inside front (42) and the third rear sprocket (16 or 18).

Tools needed - Chain breaker, $10
Options - new chain, BMX freewheel, $30 combined

I don't know how the chainline would look if you removed the old freewheel and added a new BMX fw. I think the hub is English thread, but not sure on that.

I'm wondering that. I need to take a closer look at it. It looks like a late 70's early 80's model because the paint job and logo seem more modern than the type font on it's earlier bikes. It is made in France though (not tiawan). Did motobecane convert over to the english/ISO threading around then? If it's english thread I don't think it'll be too hard to convert this. I was assuming it was french/swiss threaded.

If this all sounds confusing, I apologize. This would be my first conversion.

Did motobecane convert over to the english/ISO threading around then?

They were all over the map. My '83 has French BB and HS.

I've built a SS from scratch using road double cranks, 111mm BB and Suzue basic hubs with perfect chainline. Also, a Benotto road conversion using an old track wheel, chainline is off by about 1.5mm, working it to fine tune. So I don't have a ton of experience per se, but I do know that all problems have solutions, and they are not always expensive.

Try to develop a genuine relationship with a local mech. Try a few shops until you find the right cat. The discussions here and locally will teach you mountains of information in a short time.

right on. thanks.

Most French bikes imported into the United States used BSC (standard) threading on the freewheel. Of my eight Frenchies, the only one that has a French threaded freewheel is the 1967 PX10, which is either pre- or early bike boom. Likewise pedals; esp. on Motos, which used Japanese parts long before the other French manufacturers.

Now the bad (strange, anyway) news: Motobecane used Swiss threading on their bottom brackets for years, I'm not sure how far back, but certainly back into the early seventies. Look on the cups; if they are marked 35x1, they are likely Swiss, not French (Swiss is the same thread pitch as French, but the fixed cup is reverse threaded). Can be hard to find replacements; tho Phil Wood makes French/Swiss rings for his superb bottom brackets. Colin M, if you've never removed your fixed cup, I'm willing to bet it's actually Swiss. Now the good: if the bearing races are still in good shape, keep it overhauled and it will likely last forever.

The Nomade Sprint is not a particularly high end model. It will make a fine beater, but it's not a Frenchie I would invest a lot in, either. I would not worry about being a novice at mechanics; that's just a good reason to learn something new. Find a good book, and start monkeying around with some tools.

As Colin M said, try to develop a relationship with a local mech. Find one who at least one who has some feel for older French stuff; to too many shops, a French bike might as well be a flying saucer. You should always talk to any mech before taking a Frenchie to them.

Actually this advice is good for anything be it an old stereo or car. Even a computer for that matter.
Too many people claiming to be knowledgeable really do not know anything beyond 'throw out and replace'.

So standard threading on the freewheel would mean that I can attach a track cog on to the rear hub with relative ease, correct? Also, I think sheldon brown sells swiss bottom brackets and spindels for about $100. I would like to try to avoid this at all costs, but if I was to buy a new crank and chainring, would I need to replace the entire bottom bracket?

So this is the way I see it for a cheap conversion if the bottom bracket and rear wheel are intact, I would need to:

attach fixed cog to rear hub via lockring and adhesive
buy new chainring attach to existing crank or buy new crank and chainring (if it's french or swiss threaded bottom bracket, do I need to buy a compatible crank?)
buy new chain
remove gear shift levers on stem and brake levers
new tires and tubes.

and then I'm set?

Again, this is the way I see it in my head, but it may not make any sense.

"So standard threading on the freewheel would mean that I can attach a track cog on to the rear hub with relative ease, correct?"

Yes, but backpedaling will loosen it, so add a bottom bracket lockring on top of it to keep it snug, and install a brake, naturally.

"Also, I think sheldon brown sells swiss bottom brackets and spindels for about $100. I would like to try to avoid this at all costs, but if I was to buy a new crank and chainring, would I need to replace the entire bottom bracket? "

Probably not. You would space / dish the rear wheel to mate up with whatever front-end arrangement you decide on, old or new. See below...

"So this is the way I see it for a cheap conversion if the bottom bracket and rear wheel are intact, I would need to:
attach fixed cog to rear hub via lockring and adhesive

Yep


"...buy new chainring attach to existing crank or buy new crank and chainring (if it's french or swiss threaded bottom bracket, do I need to buy a compatible crank?)"

No - I say use what you have. Pick the big or small chainring, buy a set of single stack chainring bolts, and put the chainring on the inside or outside of the crank spider to suit the chainline as required. French vs English vs Swiss involves the threads in the BB shell only, not the spindle / crank assy.

"...buy new chain"

Sure.

"...remove gear shift levers on stem and brake levers"

Leave the brakes on for now.

"...new tires and tubes."

Couldn't hurt, but not necessary if they appear intact.

"...and then I'm set?
Again, this is the way I see it in my head, but it may not make any sense."


Let's see what the consensus says. I think that's it.

I think colinm said it all. Good luck

Keep the crankset, just remove the unnecessary rings (need stack bolts to re-assemble).
At least keep the front brake for now. Keep the tires, just rotate the front to the back.

You might be happier in the long run by having a dedicated fixed wheel built for you, it's more
money out-of-pocket, but a longer-term investment than a bum-bike set up.

I converted an '83 Moto Mirage this way for a friend, and it worked out just fine.

I'm considering buying a flip-flop or fixed hub wheelset instead of rigging the rear wheel. I think harris cyclery has 27" wheelsets for relatively cheap. Maybe I can get a LBS to build a set for a reasonable price. I think I need to replace the brakes (or at least pads) for sure. They're scary. If I have aluminum wheelset built, would I need to replace the brakes in total? (Old weinmann brakes).

Center-pull, short-reach Weinmann's I presume?
You would only need a different brake if you go with a 700c wheel.
The pads on the old Weiners wouldn't reach the rim in that case.

please please please don't rig the rear wheel. do it right, not right now. if you get new wheels, just get some salmon colored kool-stop pads. you shouldn't have to replace the brakes, unless you get some 700c wheels for it. are they the center pull type? those work great with decent pads. my first fixie was a peugeot. i had some 27" wheels built for it. i still have it, still ride it, and never plan to get rid of it. i also love french bikes.

Are these steel wheels? if it's in your budget you could pick up a new (cheap) wheelset with an actual track hub for around $120.

the problem with these threads is that we don't really know what you mean by wanting to keep it cheap. It would be nice to know what you mean by this, as in 'I want to spend $50' or, 'I want to spend $25' or whatever.
It'd also be helpful if we knew what kind of RL help and tools you might have access to. For example, if you were my neighbor, you would come over and we'd take off your freewheel and try to thread a track cog on, answering several questions in about 10 minutes.
Your best bet is to find a local fixed bike nerd and give him a 12 pack to spend a few hours with you and your bike. Anyone in Chicago want to step up?

I'd be willing to spend about $100 on the conversion. If I buy a wheelset that of course would jump dramatically. The wheels are steel and weigh a ton. I really don't have access to tools. I figured I'd be spending the majority of $$ on tools, but there is a great used bike shop (urban bikes) not to far from where I live. I might be able to find some old aluminum rims for cheap and other parts as well as have them help me. I'm not sure how that works though because I'd really like to do the actual work (as I like building **** and is part of the reason for the conversion).

http://www.fixedgeargallery.com/2004/c/kresge31.jpg

This has since been cleaned up and redone but the drivetrain is the original.

My understanding is that Marcus at Yojimbo's knows everything.

http://www.yojimbosgarage.com/

And, that you can work on your bike at Working Bikes Coop (check with them to be sure) ... they have tools and usually a bunch of guys around who know what they are doing.

http://www.workingbikes.org/

Yeah, working bikes coop is where I got the bike, but from what I hear, they don't like people using there tools. I could be wrong seeing as it's what I heard through a friend of a friend.

This gives me hope.

I thought that's what coop's were there for? WTF?