moby gearing question

Recently upgraded my 40t to a variator from the dimoby clutch. Next on to do list is change the gearing. Currently it's 11:44, and was wondering if better to go to 52 or 54 on the rear. It's just that I've found conflicting info while searching what the stock gearing was for variated models. Also I found a thread where rebel mentioned that dimoby models came in 3 "flavors:"

12 x 44 = 3.67 (20mph Dimoby)

11 x 48 = 4.36 (25mph Dimoby)

13 x 52 = 4.00 (30mph Dimoby)

The badge behind forks says it's a 25 mph version, but the gearing does not correlate with any of the above. Did motobecane always stick to this recipe? The bike seemed 100% unmolested when I picked it up.

Only other changes have been a 15 sha, mlm intake, new ax30 belt, long hook bracket, mildy de-restricted "newer" blunderbuss.

Re: moby gearing question

You can actually pick your own flavour of gearing to match where you ride and the laden weight on the bike (bigger folk will have slower rides). Keep in mind that if you change the front sprocket you will need a matching pulley because that engagement arm (attached to the Velo-Moteur switch) is different for each sprocket size.

MobySprocketSets.JPG

AND if you are clever and resourceful you could play mix n match from other brands for the driven sprocket on the rear wheel. Need to rework the center hole on some and possibly drill new attaching hardware holes.

MixedGearSets.jpg

The actual what makes the difference between a 20 - 25 - 30 (or A-B-C or C-B-A depending on the year) is a whole collection of different components... but gearing is the main factor

20_25_30differences.JPG

Re: moby gearing question

Chris Straub /

Sweet, thanks for the info! Going to keep the 11 tooth on the pulley to keep things simple I think. Any suggestion on what rear sprocket on a slightly hilly area for my 215 lbs? Was planning on ordering either a 52 or 54...and going to stick with stock cylinder and deresticted blunderbuss. I’ve cleaned/regreased variator, pedal shaft, wheel bearings, and speedo drive, replaced all 3 motor bushings (made sure top 2 are not overly tightened) and have the slide on the 15 sha fully opening. I do still have to set timing to 1.5 btdc as I’ve seen you suggest. Been hitting low 30’s with current gearing/timing, but haven’t tested it again yet since swapping out for larger hook last night.

> Rebel Moby Wrote:

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

> You can actually pick your own flavour of gearing to match where you

> ride and the laden weight on the bike (bigger folk will have slower

> rides). Keep in mind that if you change the front sprocket you will

> need a matching pulley because that engagement arm (attached to the

> Velo-Moteur switch) is different for each sprocket size.

>

> AND if you are clever and resourceful you could play mix n match from

> other brands for the driven sprocket on the rear wheel. Need to rework

> the center hole on some and possibly drill new attaching hardware holes.

>

> The actual what makes the difference between a 20 - 25 - 30 (or A-B-C or

> C-B-A depending on the year) is a whole collection of different

> components... but gearing is the main factor (edited)

Re: moby gearing question

I always run a 56 rear but I'm heavier than you. With your weight I'd run a 52. Most stock bikes I've seen run a 54.

Re: moby gearing question

54 or 56 on the rear, it wont matter much which you run, Mobys are funny, like my fast av10 does 57mph at 10x54, I changed that to 12x54 and could only do 40-44, they like RPM's

Re: moby gearing question

Indeed the AV10 motors love the revs.

Maybe the winter is a goodly time for in depth playing and just get her running well for fun now. Find some stuff on Buy/Sell or local bike nutz to rework and experiment...

Perhaps make some plans to to the mild port job once the winter starts sending crappy weather and you have some downtime. Stock 50V mild ported and transfer lead ins reworked, with a 15mm SHA + 15mm derestricted intake (matched to the cylinder) and first gen blunderbuss exhause derestricted to 11mm, points ignition set to 1,5mm BTDC. The closed chamber head has had the spark plug unshrouded and flow corrected then resized to 5cc. Other mod is the stock counter spring is stuffed. Stock gearing. 17x2.50 tires.

Gets my 90kg (about 200 pounds) butt plus the side car to 60km/h (about 37mph)with some reserve for right cornering and staying out of trouble. Reliable all day long and into the night. Most of the roads I am on are quite flat.

Re: moby gearing question

Chris Straub /

Was going through my sprocket collection and found a 52 tooth that I didn’t know I had, must have come with extra parts from a previous bike purchase. Going to throw that on there for now and see how she does. Thanks everyone for all the pointers, and happy turkey day

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