motorized bicycle 44 to 36 tooth sprocket swap

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happycheapskate

happycheapskate

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Nov 26, 2009
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Rockwall TX
I have a 38tooth on a 70lb beach cruiser with a 48cc grubee. I have to pedal to about 10mph then the bike will accelerate even up steep overpasses, with a bunch of canned food in the basket. It is not neck snapping fast, is not as fast to speed up as the 44t was, but easily pulls all the groceries I can carry (in milk crate and a backpack!). It was well worth it. I think the bikes only come with the 44t because its cheap for the mfgr and "governs" the speed of the bike to about 25mph for less liability. If you ride off road or at 5-15mph leave your stock cog on.

Kristof said:
So, how much torque will I loose with a 36 or 40?

I wouldnt mind pedal assisting uphill.

How fast would i need to get going in order to engage the engine? I need to know, because there are steep hills around my area.
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Rmerac

Rmerac

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Aug 29, 2011
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Independence, MO
I was thinking of replacing the standard 44t sprocket that comes with the kit with a 30 something.. would this mean an increased top speed..? Also, what are some fallbacks of switching?
 
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Nikko

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Jun 23, 2011
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So Cal
go with a 32 at most, i had a 32 and couldnt even get to the top of my rpms, if i were you i would get a 36 to stay balanced. with the32 i was only hitting 32 on a good day, i have a shift kit now
 
mapbike

mapbike

Well-Known Member
Mar 14, 2010
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Central Area of Texas
A 36T is a good choice for many builds and conditions as long as hills in area aren't too extra steap and too extra long.

I weigh 200lbs and my bike with a 36T pulls me very good, cruises at 30-32mph very nicely.

I have good free flowing exhaust, head has been shaved a tad, I have the ported Manic intake and my NT carb. has been rejetted so engine doesn't run to rich as most all do until the carb is jetted down a bit.

36T is about the best all around for me and many others.

peace, map
 
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Nikko

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Jun 23, 2011
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how much did you shave off the head? im considering doing that but want to try manic mechanics high compression head also
 
happycheapskate

happycheapskate

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Nov 26, 2009
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Here is a video with a 38tooth and Grubee 48cc. (I used a 5 hole cog for Front Freewheels,and turned it out to fit my hub and the 9 hole donut.) 36 shouldn't be much different. 30 might be more than your engine can consistently "get on top of" unless you have a pedal gear you can use when it bogs. I only pedal to take off , and when going less than 15mph. moped short clip ride 5min.wmv - YouTube Bikeberry.com sells 36 tooth cogs now for the stock rag system or adapters. In the video I am not running it WOT, probably half to 3/4 most of the time. I give it WOT to go up the bridges though, but let off some because was trying to keep the wind noise down.
 
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mapbike

mapbike

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Mar 14, 2010
5,502
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Central Area of Texas
I'm sure the manic head will be a better way to go, but I just take about 0.015 off mine + or - 0.002 or so, this will make a noticable compression increase.

peace, map


Nikko said:
how much did you shave off the head? im considering doing that but want to try manic mechanics high compression head also
Click to expand...
 
mapbike

mapbike

Well-Known Member
Mar 14, 2010
5,502
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Central Area of Texas
happycheapskate said:
Here is a video with a 38tooth and Grubee 48cc. (I used a 5 hole cog for Front Freewheels,and turned it out to fit my hub and the 9 hole donut.) 36 shouldn't be much different. 30 might be more than your engine can consistently "get on top of" unless you have a pedal gear you can use when it bogs. I only pedal to take off , and when going less than 15mph. moped short clip ride 5min.wmv - YouTube Bikeberry.com sells 36 tooth cogs now for the stock rag system or adapters. In the video I am not running it WOT, probably half to 3/4 most of the time. I give it WOT to go up the bridges though, but let off some because was trying to keep the wind noise down.
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I have 2 stock engines that will hit 34-38MPH with one having a 41T and the other having a 36T sprocket, 30MPH is easily obtained with a bone stock engine and a 36T toothe sprocket as long as the carb is tuned properly and it has a free flowing exhaust.

Peace, map
 
george_n_texas

george_n_texas

Member
Sep 4, 2009
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Texas
Rmerac said:
I was thinking of replacing the standard 44t sprocket that comes with the kit with a 30 something.. would this mean an increased top speed..? Also, what are some fallbacks of switching?
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It really depends on how much you weigh Happy weighs like 150 if his clothes are wet LOL you are right to assume a higher top end if you hit a pot-hole going fast LOOK OUT! I prefer the 50 tooth aproach as speed is never going to get much over 30 MPH so it really falls down to how much peddle assist you want to do. Be safe
 
retromike3

retromike3

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Jan 9, 2009
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Beaverton OR
The fact is that my road pedal bike is a faster machine. my motor bicycle. even with the 36 rear and tuned pipe only gets a top speed of about 27 mph. (According to my Iphone app) Going the same rout my top speed on my road bike was 54 mph.

mikef
 
Saddletramp1200

Saddletramp1200

Custom MB Buiilder
May 7, 2008
1,451
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Houston, Texas
Where do We start? A machine that is to be operated at 10 mph or less go twice that? Tires get hot and fail, Wheel bearings were never made for such a speed. You make it better, or you get hurt. Real chance of being dead over 5 MPH. I wish to offend no one. (c) My Quest is to keep you Guys safe. That's my goal. dance1
 
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xenodius

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May 23, 2012
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Spokane, WA
Saddletramp1200 said:
Real chance of being dead over 5 MPH. I wish to offend no one. (c) My Quest is to keep you Guys safe. That's my goal. dance1
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5 mph is powerwalking speed... I think the greatest danger to any of us riding these bikes on roads is other vehicles, not ourselves. Don't get me wrong, I've had my disc brakes seize at WOT-- not cool. But I didn't layover; I was more concerned about being run over.

And I agree that 40, 50, 60 mph is a lot more than many of these bikes are designed for, especially cheap Wally cruisers and such. But I've been 60 on a roadie (great fun on the flats!) and while somewhat alarming, I felt totally comfortable. It was a very well built bike, great tolerances, light enough for two fingers easy. My point is, not all of these bikes are junk. I've replaced the hubs, headset, and shocks on my cruiser, and I trust them. I still don't think I'd care to go over 35, though.
 
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xenodius

New Member
May 23, 2012
150
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Spokane, WA
Need help. I just tried swapping to a 36 tooth sprocket; had a 6-hole hub adapter for the 44 tooth, using the 9-hole method for the 36t. I don't know if I got the wrong size or what... the holes on the sprocket are a little larger than the fiber washers, but the holes on the metal washers are way larger than the sprocket. I've been messing with this thing for hours, literally... >.> It is TIGHT!

Pic: http://imgur.com/59wI0

How did you manage to get this thing put together on the wheel? I can't even do it on one half without the metal washers overlapping. Should I dremel them down? Please advise... :-||
 
george_n_texas

george_n_texas

Member
Sep 4, 2009
980
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Texas
xenodius said:
Need help. I just tried swapping to a 36 tooth sprocket; had a 6-hole hub adapter for the 44 tooth, using the 9-hole method for the 36t. I don't know if I got the wrong size or what... the holes on the sprocket are a little larger than the fiber washers, but the holes on the metal washers are way larger than the sprocket. I've been messing with this thing for hours, literally... >.> It is TIGHT!

Pic: http://imgur.com/59wI0

How did you manage to get this thing put together on the wheel? I can't even do it on one half without the metal washers overlapping. Should I dremel them down? Please advise... :-||
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I'm thinkin use only 2 of the plates spaced as equally apart as possible.
 
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