WestyNaut92

Hello all! This is my first time posting here, I've recently gotten incredibly into bicycle maintenance. I'm having a few issues though, my bike is an 198X (although probably 1983-1984) Motobecane Super Mirage 12 speed, and as it currently sits, it's got a broken back axle. It rides decently enough, but my question is would it be easier to just get a new 27x1-1/4 QR rear wheel and 6 speed Shimano freewheel, or should I go through the trouble of replacing the axle?
I'd also like to know if it'd be worth it to get a new rear derailleur, and how to know which ones fit, or if they're all just sort of standard.
I'm aware it's not worth that much money, but I'm quite enamored with my bicycle.

markk900

First off welcome! I'm sure you'll get plenty of advice on this and your future purchases from the folks here.

How do you know the axle is broken? Assuming it is, and assuming you want to get even further into bike maintenance, I would replace the axle. If you have a vintage friendly local bike shop (LBS) or bike co-op, it should not be hard to find something that works. You will likely need a tool to remove the freewheel, but otherwise should be straightforward.

I can't see from the pictures very well, but it appears you have a SunTour VGT on the back....that is considered an upgrade for most people so not sure why you would want to replace it....if you do though, they are pretty standard if you stay in the vintage world - just remember you will need one with the claw that mounts it to the frame - higher end bikes had the hanger as part of the rear dropout.

I assume you have been lurking and know you can get a pretty accurate idea of the year of your bike though decoding the date codes on the components - check out Vintage Trek Bikes- Information on Steel Road Bicycles made by the Trek Bicycle Corporation, bike for the section on Suntour and Shimano date codes.

romperrr 

Axel) if you have the time and willingness, learning how to rebuild an axle is useful as you'll in turn learn out adjust a hub. Be prepared to be frustrated

Derailleur) most derailleurs have the same threading, but a few don't. I can't say for yours, a close up of the unit would help. Is it a bolt on or claw type?

WestyNaut92

One end of the axle is bent up, and I can grab each end of it and rotate it different directions at the same time. The Derailleur is a Suntour VX GT, and with adjustment it shifts well...although it hasn't wanted to shift into the highest (smallest cog) gear in a while now. I've tried the adjustment screws, but that could be me needing to replace the cable and the chain (pretty sure that's worn out too).

I'm slowly acquiring bicycle specific tools, I think my next project is going to be a BB rebuild, just to 1) learn how to, and 2), make sure it's in working condition (As I've read this bike may have French or Swiss threading, which is apparently a pain), that and a headset rebuild, again, just to make sure it's in good shape and to learn.

As far as the derailleur hanger, it does appear to be part of the rear drop out.

Velocivixen

Welcome! My first vintage bike was a '74 or '75 Motobecane Grand Jubile. First thing I did was the headset. I read on this forum & Sheldon Brown about how to do it. Had so much fun as well as frustration. Had to take my bike to the bike shop a couple of times, but mostly I did it all myself.

Good idea about obtaining tools as you go along. Have a great time. Now that you've dipped your toes in the water, we will expect photos.

WestyNaut92

Hah, I've already got a spoke wrench, a pedal wrench, and a chain whip! I keep wanting to buy a set of fenders for it...and some nice handlebar tape, actually decent tires, a good saddle....

ncrnelson

It certainly does snowball doesn't it? You can't spoil a bike by buying it too many goodies and of course the man who dies with the most tools wins.

Or woman, to be fair.

WestyNaut92

I've got the added bonus of having a girlfriend who finds greasy hands appealing.

oddjob2

If it is a Maillard Helicomatic freewheel and hub, get a whole new wheel. You can probably find one locally for $25, or an alloy pair for $40-$50. If you get a pair, 700c should work as well as 27". If you want new:

Sun Velomine.com : Worldwide Bicycle Shop, fixed gear track bike wheelsets campagnolo super record vintage bike

If it is a Suntour hub, you can pretty much get a generic QR axle with cones. Just double check spacing between the dropouts, probably 126mm

Summit Rear QR Axle Set M10X126X136

WestyNaut92

Update: It is Maillard rear Hub. The freewheel is too dirty to tell what it is. I ordered a new rear wheel and a Shimano 6 speed freewheel, should be here middle of next week! I'll take pictures and all that jazz!