What's it like running a 36T sprocket?

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biknut

Well-Known Member
Sep 28, 2010
6,631
409
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Dallas
My first build was a 50, running a 40T sprocket. It's tire size is 2.125 x 26. That gearing seemed just about perfect. Top speed on a long enough straight is a little over 30 mph, and it cruises comfortably at 25 mph.

Now I have completed a new build. It's an 80, running the same 40T sprocket, but the tire size is a smaller 1.95 x 26. I didn't realize there would be so much difference in gearing from the tire being slightly smaller diameter.

In comparison to the 50, the 80 races up to the red line, but is barely doing 30 mph, and sounds like it's going to explode at that speed. It feels like there's very little load on the engine at top speed. The 50 accelerates up to about 28 then takes it's good old time, to get above 30. Above 28 it feels like the motor is working hard. On the 80 cruising above 20 mph the engine feels very busy, and almost no load, where the 50 could go all day cruising 25 and feels about right load wise.

Obviously the 80 is under geared. I'm planning to change to a 36T sprocket, but my question is, how will that effect coming out of the hole, and cruising around at ultra slow speeds? How slow can you go?

I realize it's impossible to have perfect gearing at every speed with only one gear, but I'd like to increase the cruising speed without ruining the low speed operation.

What I'd like to hear from you is your riding impressions from running a 36T sprocket.



Edit> I added my riding impression after installing my new 36T sprocket.



Today I installed my new 36T Kings sprocket. I just got back from a longish test ride, and I have to say, it really hits the spot on the Cadillac.

For anyone reading this thread trying to decide if a 36T is right for you, the descriptions from everyone that replied to this thread up till now are right on.

This is my impression.

I like this 36T a lot better than the 40T I took off. On my other bike which is a 50cc, a 40T works great. I wouldn't want to gear it any higher, but this 80 is a different story. Cruising on the 50, which has a little lower vibration level, 25 mph is no problem, and blasts up to 30 mph are possible, but it gets pretty buzzy. The 80 with the same 40T feels very buzzy at 25 mph. It only liked to cruise up to about 22 mph. It felt under geared, like there was almost no load on the motor. Now with the 36T, there's just enough load to kill most of the vibs. 25 mph is no longer any problem at all, and even cruising at 30 mph isn't too bad. I even blasted up to 35 mph no problem on flat road, with no wind. Before, if I tried to do that it felt like it was going to blow up way before 35.

One of my main concerns about a 36T was how hard it was going to be coming out of the hole, but really, I can hardly tell any difference. Very low speed riding isn't much different either. I wasn't too concerned about hills. We don't have many big ones where I live, but the ones I do ride don't seem much different. Still a little better than the 50. Big hills probably would be a problem in some parts of the country with a 36T though, so take that into consideration. As far as acceleration on the flat, I can't tell much difference riding by myself.

All in all this was a big improvement.
 
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Nashville Kat

Well-Known Member
Apr 20, 2009
1,501
55
48
Jacksonville, Florida
I love my 36- but cruising really slow is a bit difficult- and you do lose some torque at takeoff-

I also have THIN tires- a 27 x 1 1/4 on the front, and a 26 x 1.75 on the back with a 66 motor- I coast a lot and shut the motor off a lot- and peddling's real easy

Yeah, unless I'm over twenty- I'm barely giving it any throttle- but at a nice cruise, the motors never really revved out either- I like mine
 

biknut

Well-Known Member
Sep 28, 2010
6,631
409
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Dallas
I love my 36- but cruising really slow is a bit difficult- and you do lose some torque at takeoff-

I also have THIN tires- a 27 x 1 1/4 on the front, and a 26 x 1.75 on the back with a 66 motor- I coast a lot and shut the motor off a lot- and peddling's real easy

Yeah, unless I'm over twenty- I'm barely giving it any throttle- but at a nice cruise, the motors never really revved out either- I like mine
Thank for the good discription. That's helpful.
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
I have a 36T on one a 34T on another and a 41T on another, by for for the kind of riding I do the 36T is my favorite...... 41T is ok @25MPH but I can comfortably cruise at 30-32MPH with the 36T and it is a little bit easier for the engine to pull than the 34T although there really isnt that much of a noticable difference, just slightly maybe.

I think 36T is the best all around gearing as long as you aren't in an area where you have lots of long steep hills and you are about 210lbs or less.

Just my $.02 good luck with whatever you decide.

Peace
 

DuctTapedGoat

Active Member
Dec 20, 2010
1,179
10
38
38
Nampa Idaho
I love my 36T - still can pull off the line fairly well, and a good top end.

Been on it for about 6 months, keeps the RPMs down just enough to hit a good 30mph cruising speed.
 

biknut

Well-Known Member
Sep 28, 2010
6,631
409
83
Dallas
Thanks for the replys everyone. The descriptions of higher speed operation sound like exactly what I'm looking for, and what I was expecting. My main concern was the, off the line, and low speed operation, but nobody seems to be complaining about it. It sounds like any trouble down there is more than made up for by decent cruising speeds, and vibration levels.

I'm going to order a 36T as soom as possible.
 

biknut

Well-Known Member
Sep 28, 2010
6,631
409
83
Dallas
Today I installed my new 36T Kings sprocket. I just got back from a longish test ride, and I have to say, it really hits the spot on the Cadillac.

For anyone reading this thread trying to decide if a 36T is right for you, the descriptions from everyone that replied to this thread up till now are right on.

This is my impression.

I like this 36T a lot better than the 40T I took off. On my other bike which is a 50cc, a 40T works great. I wouldn't want to gear it any higher, but this 80 is a different story. Cruising on the 50, which has a little lower vibration level, 25 mph is no problem, and blasts up to 30 mph are possible, but it gets pretty buzzy. The 80 with the same 40T feels very buzzy at 25 mph. It only liked to cruise up to about 22 mph. It felt under geared, like there was almost no load on the motor. Now with the 36T, there's just enough load to kill most of the vibs. 25 mph is no longer any problem at all, and even cruising at 30 mph isn't too bad. I even blasted up to 35 mph no problem on flat road, with no wind. Before, if I tried to do that it felt like it was going to blow up way before 35.

One of my main concerns about a 36T was how hard it was going to be coming out of the hole, but really, I can hardly tell any difference. Very low speed riding isn't much different either. I wasn't too concerned about hills. We don't have many big ones where I live, but the ones I do ride don't seem much different. Still a little better than the 50. Big hills probably would be a problem in some parts of the country with a 36T though, so take that into consideration. As far as acceleration on the flat, I can't tell much difference riding by myself.

All in all this was a big improvement.
 

Dave31

Active Member
Mar 1, 2008
11,199
47
38
Aztlán, Arizona
I run a 36t and love it. I can cruise at 20mph or hit the upper 40's with it to have some fun. Not only does my bike run smoother with the 36t but I also get better fuel mileage.

I have never had a problem with take off and run up some steep hills and mountains with it and can average near 20mph going up some very steep grades.

The only thing I dont like is when I go off-road on really ruff terrain, a little more low end would help me get thru the nasty stuff. Many times I end up stalling the motor out.
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
36T is the best all around for me, I have a 34T on one bike I got from Kings and I like it as well, it's an Alum sprocket instead of the steel 36T I made up myself from a kids bike crank sprocket.

I cant tell any speed or power difference between the 34 and 36, I have a 32T but haven't tried it yet so not sure what my results will be on it, may be a bit of a high gear for where I ride but it might work, yet to be seen.....shrug!

My Huffy Karaoke has almost 700 miles on it now with the 66cc & 36T sprocket and it's the best riding bike of them all, plenty of power and very comfortable bike.

Peace
 

Maniaman

New Member
Sep 25, 2010
15
0
0
West Jordan, Ut
My first build was a 50, running a 40T sprocket. It's tire size is 2.125 x 26. That gearing seemed just about perfect. Top speed on a long enough straight is a little over 30 mph, and it cruises comfortably at 25 mph.
its funny you say this, i run 2.125 x 20" i gps tested my speed topped at 27mph.... weird
Edit: w/ 44 tooth sprocket & 66cc grubee

xct2
 

flatblack

New Member
May 22, 2011
374
1
0
Fairfax, VA
My MM hub adapter/sprocket combo is almost here. I went with a 40t...now I'm thinking I shoulda went lower. My mill is a Jet 66cc with SBP xchamber, Puch Hi Hi comp head, slight port/polish job, NGK plug/wire. Before the laydown, at just over half throttle, she saw 30mph. Never had a chance to push it to wide open...
 

biknut

Well-Known Member
Sep 28, 2010
6,631
409
83
Dallas
Yep 36T is da shizz on a 80 motor. Now that I've had more time riding with it I like it even more. Cruising at 25 is cake, but what I really like is if I need to because of traffic, I can cruise at 30 with no problem too. I probably wouldn't go across town at 30, but for a 1/2 mile sprint it's not hurting anything. I could almost consider one or two more teeth, because the power is still pertty good. All in all though I think this is about perfect.
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
Go to this link and ask your question here DIY Home Built Motorized Bicycle (non kit) - Motorized Bicycle: Engine Kit Forum this will be an area that should get the attention of someone who may be able to give you an educated answer, because there are several fella's who hang out there that have built multiple weed wacker set ups.....

Hope this helps you find the answer you are looking for.

Peace







I am planing to build a weedwacker engine powered bicycle. I have one question, what gear ratio is on your rig?