Best rear sprocket size

[Tyler6357]

how com none of you don't just buy a motorcycle

why?
A motorized bicycle can go places a motorcycle can't, I can always cut my engine and peddle over pike paths.
A motorized bicycle doesn't require DMV renewal every year in my state like a motorcycle
A motorized bicycle is easier to transport than a motorcycle, I can put 2 or even 3 of them on the rear rack of my Motorhome and they are light and easy to deal with.
It's an awesome hobby for amateurs like me and it's crazy fun!

 

[clay830]

I was just talking more for driving purposes. Ive seen a lot of people say they use motorized bicycles for transportation and was wondering why people don't buy a cheap 55+ mph small motorcycle?

 

[TheNecromancer13]

Because I can build a 55 + mph motorized bicycle for 1/10th the cost of a motorcycle, and use it for transportation, and I can say "I built it" when people ask where I got it.

 

[Kartooo]

how com none of you don't just buy a motorcycle

i have owned several dozen motorcycles, my 1st was 50 yrs ago. i enjoy the simplicity of these motorized bikes. 2 wires, not like the fistfulls of wires on a motorcycle. the 100+ miles to a gal, $15 for a tire not $115, nice to slow down and smell the roses not everything flying by in a blur. it's a hobby, enjoy it, don't pick it all apart and look for faults, life is too short.

 

[clay830]

Because I can build a 55 + mph motorized bicycle .

Well have you?

 

[TheNecromancer13]

Yes. 68 mph, actually.

 

[clay830]

Nooice was it a 2 stroke

 

[xXNightRiderXx]

If I remember correctly, I think it was his 212 predator build.

 

[TheNecromancer13]

Nope, I've not yet done a 212 cc build. Several 79 cc builds, which go about 40 or so. But my 68 mph bike uses a 125cc lifan engine, and if I adjusted the gearing, I could probably go over 100 mph. I won't do that though, 68 is fast enough for now. As it is, 1st gear has a top speed of 6 mph, 2nd gear goes about 13, and only 3rd and 4th gears are actually useful. Here's a picture (it's not quite finished yet though, still have to add a few things like headlights and paint all the exposed metal):

 

[xXNightRiderXx]

Oh, that is beautiful. I think I'm in love...

How much did it cost to build?

 

[TheNecromancer13]

So far I've got about $2,200 in it, but once I add super bright headlights, and taillights, and hand guards, and a few other things, I'll probably have spent about $2800-3,000. Plus the $800 I spent on full motorcycle safety gear so I can maybe not die if I crash.

 

[Tyler6357]

That's a hard core bike Necromancer! Good Job! It's so long, how much does that weigh? Those mag rims are very nice, what size tires are you using?

 

[TheNecromancer13]

I haven't actually weighed it yet, but it definitely weighs over 120 lbs. The engine alone was 48 lbs, and the bike is thick steel frame, so about another 50 lbs there. I'm using 26" tires, with 180 mm discs on both wheels.

 

[5-7HEAVEN]

Funny how none of the posters mentioned.....shift kit.

With a shift kit, you get the best of all worlds: super big wheel sprocket(99-tooth) for take off and giant hills, 44t at 6th gear for power, and 38t for 7th gear AND 32t for 8th gear at the high end.

 

[xXNightRiderXx]

Funny how none of the posters mentioned.....shift kit.

With a shift kit, you get the best of all worlds: super big wheel sprocket(99-tooth) for take off and giant hills, 44t at 6th gear for power, and 38t for 7th gear AND 32t for 8th gear at the high end.

Funny, I did mention a jackshaft in post #50.i said it will give you the maximum speed possible while allowing you to climb mountains.

 

[5-7HEAVEN]

"If you have a welder or know someone who does, get a go kart jackshaft. That will completely eliminate the need for a rear sprocket, but you'd need to take the pedals off. That is not to say you absolutely need a pull starter, but you would have to put on the left side pedal every time you want to start it. The jackshaft will allow you to get to the highest speeds possible, while being able to climb mountains."

You suggested installing a gokart jackshaft and removing the pedals, then putting on the foot pedal as a kickstarter.

I can't wrap my head around how your idea works. Can you explain?

There's a big difference between a jackshaft and a shift kit. A jackshaft can be used to relocate the engine chain from 2" to the other side of the bike. While doing so with the proper sprockets, a jackshaft can increase/decrease leverage and gear ratios. A jackshaft does not allow you to entertain more than one gear.....UNLESS you install the shift kit.

Then you can keep the foot pedals working.

A jackshaft can be part of a shift kit. It is not the shift kit. I have a shift kit on my 8-speed bike. However, I don't have a jackshaft.....unless you consider my bottom bracket a jackshaft.

SBP has bolt-on shift kits with a bolt-on jackshaft.

 

[5-7HEAVEN]

another problem I'm having is with my chain. I tried shortening it 1 link because it was to long and the top half of the chain (going into the engine) was sagging and rubbing the bottom half. I shortened it and now the chain is to short and the master link won't reach both ends of the chain. What should I do? Add a half link/offset link?

Wow! You had a lot of slack!

Take the chain off the rear sprocket. Install the master link. Put the bottom half of the engine chain onto the wheel sprocket. Roll the tire counter-clockwise until the chain climbs onto the big sprocket.

If you only removed one link from that really loose chain, it should now fit well.

 

[xXNightRiderXx]

"If you have a welder or know someone who does, get a go kart jackshaft. That will completely eliminate the need for a rear sprocket, but you'd need to take the pedals off. That is not to say you absolutely need a pull starter, but you would have to put on the left side pedal every time you want to start it. The jackshaft will allow you to get to the highest speeds possible, while being able to climb mountains."

You suggested installing a gokart jackshaft and removing the pedals, then putting on the foot pedal as a kickstarter.

I can't wrap my head around how your idea works. Can you explain?

There's a big difference between a jackshaft and a shift kit. A jackshaft can be used to relocate the engine chain from 2" to the other side of the bike. While doing so with the proper sprockets, a jackshaft can increase/decrease leverage and gear ratios. A jackshaft does not allow you to entertain more than one gear.....UNLESS you install the shift kit.

Then you can keep the foot pedals working.

A jackshaft can be part of a shift kit. It is not the shift kit. I have a shift kit on my 8-speed bike. However, I don't have a jackshaft.....unless you consider my bottom bracket a jackshaft.

SBP has bolt-on shift kits with a bolt-on jackshaft.

A jackshaft can be a shift kit, but you would have to have the right sprocket on the other side to use an extended chain. Or, you can do exactly what sbps kit does and have one chain driving the chainrings, and the other driving the rear wheel. Or, you can have the shaft directly drive the rear wheel, completely bypassing the chainrings. This will require a pull starter, and you wont be able to pedal. Note that this requires a bit of ingenuity to make work, and won't always be possible. It's a lot more work for a lot less money. I actually just contacted sbp asking if their 4 stoke shift kit can be modified for a 212cc, and I will be attempting to have that bike registered, licensed, and insured, for safety reasons, and so the cops don't pull me over on my way to Washington asking me what the **** I'm doing on the freeways. Lol.

 

[5-7HEAVEN]

It's interesting how you speak in generalizations.

Similar to generals who issue the orders to their commanders:

"Make it happen".

 

[xXNightRiderXx]

It's interesting how you speak in generalizations.

Similar to generals who issue the orders to their commanders:

"Make it happen".

Who, me? Or the other guy?