Motobecane Dimboy variator upgrade fail - Crank shaft too short?

I've been reading about upgrading my Motobecane with the Dimboy clutch to the variated one, and read things about gearing differences, but I haven't read anywhere that the actual shaft wouldn't be long enough. The variator is wider than the Dimboy clutch and the bolt doesn't protrude far enough for me to fasten it. Is there something I'm missing? Can I still make it work without replacing that whole thing? I just think it's weird because I read so much about this upgrade but nothing about this!

Re: Motobecane Dimboy variator upgrade fail - Crank shaft too short?

The variator uses a different nut than the dimoby clutch. You can't put a variator on with the dimoby nut.

Re: Motobecane Dimboy variator upgrade fail - Crank shaft too short?

Re: Motobecane Dimboy variator upgrade fail - Crank shaft too short?

Well shit. Been reading about this as well and didn't realize that myself. Guess I need to order a nut as well. What's the difference in gearing? I'm assuming with the variator you could have 1 or 2 lower teeth for shorter gearing

Re: Motobecane Dimboy variator upgrade fail - Crank shaft too short?

> Buttcheeks BUZZARD Wrote:

> -------------------------------------------------------

> Well shit. Been reading about this as well and didn't realize that

> myself. Guess I need to order a nut as well. What's the difference in

> gearing? I'm assuming with the variator you could have 1 or 2 lower

> teeth for shorter gearing

Dimoby is like 11/42 and variated is like 11/54. It's easier to find a 56 though and I might have one you can get. I'll look for the nut also

Re: Motobecane Dimboy variator upgrade fail - Crank shaft too short?

Dimoby 40 ad 50 serie Mobys came in three flavours: 20, 25, 30mph rating

12 x 44 = 3.67 (20mph Dimoby)

11 x 48 = 4.36 (25mph Dimoby)

13 x 52 = 4.00 (30mph Dimoby)

Variator Mobys only came in one flavour: 30mph

11 x 52 = 4.73 (30mph Variator)

Make note that the drive gears are matched to the hardware behind the driven pulley, so a 11 gear needs a 11 gear engagement arm, a 12 gear needs a 12 gear engagement arm, and a 13 gear needs a 13 gear engagement arm. On initial install youmay think "bullshyte" however the engagement arm will fail with zero notice or warning and you will hear "the machine gun sound" and your Moby will go no further under power of the motor. (edited)

Re: Motobecane Dimboy variator upgrade fail - Crank shaft too short?

^ great info, I never knew varriated bikes were only 30mph? Sooo, can I put a 13 on the front of my model 7? It is a "b" cyl....but only seen one size rear sprocket on this model? All this time I thought the restrictions were in the cyl size. Glad you are back here!

Re: Motobecane Dimboy variator upgrade fail - Crank shaft too short?

The cylinder is a "B" or the bike speed rating is "B"?

The cycle rating of "B" means 25mph

The cylinder "B" means it is size to take a 38.940 or 38.945 diameter piston.

Re: Motobecane Dimboy variator upgrade fail - Crank shaft too short?

I bought this variator from user idmasse and he sent me the wrong outter plate too. It's too fat to fit inside the more narrow variated clutch. Not getting a reply from him after a week. How do you guys go about making sure people know about this kind of stuff? I think he's still selling Moby parts.

If anyone has the outter plate to a Moby variator let me know! I'd rather buy it from one of you than a whole new variator from treats or eBay.

Also, I have the 1980 "C" bike so 30 mph. What will happen if I don't change the gearing? I'm assuming I'll have the same not-so-great torque but more top speed, is that right?

Re: Motobecane Dimboy variator upgrade fail - Crank shaft too short?

Tons of information here on MA, just search it out before you attempt to do any mods on any moped would be a good suggestion for anyone. new or old to the moped scene. Always something to learn (or forget like us old folks experience sometimes)

1978-79 the speed rating was A=30mph B=25mph C=20mph

1980 up the speed rating was A=20mph B=25mph C=30mph

Prior to that there was no letter on the head badge, but here is a gearchart for the ratios for the earlier bikes.

Also handy as some folks have swapped wheels and pulley assemblies and all sorts of things over the years.

MobySprocketSets.JPG

> Sam R Wrote:

> -------------------------------------------------------

> I bought this variator from user idmasse and he sent me the wrong outter

> plate too. It's too fat to fit inside the more narrow variated clutch.

> Not getting a reply from him after a week. How do you guys go about

> making sure people know about this kind of stuff? I think he's still

> selling Moby parts.

>

> If anyone has the outter plate to a Moby variator let me know! I'd

> rather buy it from one of you than a whole new variator from treats or

> eBay.

>

> Also, I have the 1980 "C" bike so 30 mph. What will happen if I don't

> change the gearing? I'm assuming I'll have the same not-so-great torque

> but more top speed, is that right?

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