moby gearing

I have a 79 50V with a sha 15/15. I have 11/54 gearing I am adding a Sims pipe and want more top speed but don't want to kill my aceleration. I live in Balto. and need to be able to do 35 to 40 to keep from being run over. ( people here drive like assholes ) Should I use a 45 or 48 on the rear wheel.

Re: moby gearing

Keep your gearing stock and port your cylinder and you will easily reach 40. If you put a 45t or 48t rear on there you will lose your ability to accelerate, and it would take you a mile to reach your top speed.

Re: moby gearing

French bikes have loads of gearing options besides just swapping the sprockets. Yeah you can go with a bigger sprocket on the front or smaller on the rear but that causes a loss in your lowend power.

With a moby you can mod your vario to a 4 ball roller and run 2 balls in it or get a performance vario that makes the belt ride higher up for more gearing, you can run a fatter belt which will also ride higher on the vario, you can look for some AV88 wheels (18") for more top speed, or run fatter tires that are taller and even though its not much all of these things can add a lot of speed without loss of lowend power.

Start with your variator and a belt.

Re: moby gearing

Tracy Meade /

Gearing changes are typical and a good idea on many bikes to gain top speed, Motobecanes, I do not feel that this is necessary, and on hi-performance machines, unlike say a puch, people start to gear DOWN.

The reason for this phenomenon is that a stock puch and a stock motobecane have different engine characteristics. an e50 is a higher-revving bike stock. The stock gearing on a puch makes the puch wind out to about 7K at 30mph, whereas the motobecane is at about a puny 5100 (these are approximations, I dont know what they are spec'd at)

The Av7 is actually a lower RPM engine, and makes use of the variator and higher gearing to get it up to speed. While a stock puch may use a little taller gearing for more top speed, it works because the gearing is comparitively short stock. The motobecane at full variation seems to be close to the maximum gearing that you would really want. For comparison, it is close to maybe 17x36 gearing on a puch, which I would never dare gear to short of an 80 kit. You do get a variator, but for a stock cylinder this is pushing it.

Your key to faster motobecanes is really raising your RPM cieling through various methods you can find around. Like I said before, the really fast motobecanes will even lean towards needing shorter gearing because they will be using increadibly high Rpms.

But for anything between stock and and an all out race death machine stock gearing is pretty much fine and I wouldnt put too much thought into changing it. Although someone will always be there to disagree. That was kind of long winded.

Re: moby gearing

long winded, but good answer

Re: moby gearing

Not as long winded as if I had answered...

On a budget, look at porting, 15mm to 17.5mm carb and a goodly pipe.

Change the vario to 2 balls or add an assist spring to the counter spring to put the variator to work for you. You could also get a launch lever there to get some human input to the speed options.

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account