Motobecane project
 

I would like input from those who might have done this. I am considering turning a Motobecane Grand Jubile into a 1 x 5 bike. Right now it has Suntour barcons on it. I have tons of geared bikes and several FG/SS bikes and am kind of interested in experimenting with a 1 x setup.

The crank is a nice SR crank with the chainguard. I'd remove that and the outer ring and go with the small which is a 39.

Thoughts? Experiences you can share?

I've done this with my nishiki. The 1x# is very nice and simple. I have mine set up with a single downtube shifter.

I run a 48 x 11-28, which is sufficient for flat riding and small hills.

Chain tension and chain line is essential to preventing chain drop. Get a BB that will line your chainring at about the middle cog. Make sure you use a non-ramped ring (SS 3/32 rings). I am also partial towards chain guards just because they look cool...

I appreciate the ideas. I've read about the chainline in other threads, that is a good idea. Is the chainring issue that big of a deal? I could source a non-ramped ring I guess, but if it is set up correctly, it should have any issues shifting, should it?

Well, chainrings are ramped to facilitate shifting up front. Since you won't be shifting up front, you want a flat chainring so you don't drop the chain at the extremes in the rear (highest and lowest cog).

I found a 1978 Motebecane Grand Jubilee at the Dump the summer past. I built the bike up as it should be then decided to go for a different look and feel....
http://www.mytenspeeds.com/My_TenSpe...ll_TQF_L_1.jpg

As for chain line, it is important to get as close as you can to in-line. However, with a freewheel driven by a single crank ring, you would be wise to set the line to match the freewheel cog you will most be using. For my money, I would just run the ring on the inside of the crank and leave it there.

As for the chrank and ring itself, it is easy to clean the cranks up to look very nice, if you take the time to do so...
http://www.mytenspeeds.com/My_TenSpe...SM_Crank_2.jpg

Randyjawa, thanks for that. I'll post pics sometime this weekend. It is a beautiful example and the cranks are already looking pretty good. The more I stare at the Moto, the more I like it. It is db 531, and a little heavier than I would have expected, but I think that is due to some of the components more than anything.

You can use a 6 speed fw on most 120 mm hubs. That would give you a bit more range (or smaller jumps), and they're generally easier to find.

Thanks Due, good point. I'll think on it over the Christmas break and decide what I want to do.

Ramps won't make your chain drop. With one ring, the chain will never touch the ramps. The ramps are there to help the chain climb from a small ring to a larger one.

Yes, I guess you're right, but many ramped rings have shorter teeth and also have tooth patterns on the teeth to facilitate shifting.

This should be a sweet commuter/utility ride. I converted my '74 Grand Jubile to a 3-speed back in the mid-80s. Popped off the large chainring and had an old aluminum shell Sturmey Archer 3-speed hub laced up to a 27" Mavic aluminum rim. Put on some ESGE plastic fenders and a Blackburn rear rack and I was good to go. Rode it like that for a few years, then returned to GJ to it's original configuration and sold it. Loved those old Moto's .. I currently have a'75 Grand Jubile, a '72 Grand Record, a '72 Le Champion, a '75 Grand Jubile frame, a '74 Grand Record frame and a '73 Le Champion frame.:)

lugnutz5, I'd love to see pics of your Motos. On the local Craigslist, there is a Nexus 7 speed hub for sale laced to a 26" rim for cheap. I'm tempted to buy it and break it down and rebuild with the original rim. I've heard good things about the Nexus hubs. I'm working on another project right now so I have time to mull it over.