How much HP can be sent thru the bike chain?

[professor]

I am thinking of the derailer type chain for a shift kit project.
I am considering something radical- an in-frame twin engine Techumseh snow blower bike and it needs gears.

 

[Ghost0]

Although I could not find any specific data on bicycle chains I did find the following. A standard 41 chain is rated to 2000 pounds. A chain lesser than a bicycle chain was rated at 900 pounds so that should give you some range to go by. My marginally educated guess would say that a multi speed bike chain would be around 1000 pounds and a 410/BMX chain I would say in the 1200 pound range.

 

[5-7HEAVEN]

I'm running 4.2hp/GP460 engine thru 8-speed derailleur-type chain. I have used an expansion pipe before, which helped the engine produce more power.

JMO, my bike's "Achilles' heel" is its bike chain. I've broken many chains, but the one on the bike has been there the longest.

 

[5-7HEAVEN]

I installed an SBP expansion pipe for the Happy Time engine on my 460 engine, and a new K&N air filter. There is now more power running thru the chain, but it's holding.

 

[professor]

Good reports, apparently the dogs in the derailer are holding too. I hadn't thought aboutl them until I read a post about the stregnth of the freewheels.

 

[5-7HEAVEN]

The chain and cassette takes its worst beating at a dead stop. Methinks bike parts would last longer if you pedal first, then apply power. With my shift kit and cassette, it's impractical. First gear for the engine is the exact opposite for pedalling from a standstill, and vice versa. If I pedal off in 7th gear, then I'd have to shift all the way up to 2nd gear, then motor away. With stop and go traffic, it's not a good option. With cassette sprockets, you need to downshift through the gears before coming to a dead stop. If not. you wreak havoc on the cassette, especially when applying engine power.

However, if I had an 8-speed internal hub or a NuVinci hub, pedalling from a standstill would work. Internal hubs can shift gears at a stop. Cassette gears cannot; the rear wheel has to be in motion to shift gears.

 

[5-7HEAVEN]

Switching to 8mm chain, sprockets and NV hub. The 8mm drive is from pocketbikes, which are made to handle several HP.

 

[5-7HEAVEN]

Good reports, apparently the dogs in the derailer are holding too. I hadn't thought aboutl them until I read a post about the stregnth of the freewheels.

I believe mine are on its way out, even though the derailleur is new. Sometimes I'll miss a shift and stop the bike.Then the engine's like in neutral. I'm thinking that the chain jumped. I look down at the chain, it's still in place and I drive away from a standstill.

Go figure.

 

[professor]

5-7 here is an idea for you. Can you run the pedal side sprocket to a big chain ring (swapping out the current one- I assume the current one is small) so that you can start out in the same gear as the engine.
Glad you figured out the problem is the dogs.

 

[5-7HEAVEN]

Professor, if I did that, all my gear ratios would change drastically.

1st gear changes from 32.55:1 to 19.88:1...

Only 1st thru 4th gear would be able to be used, but not effectively.

Fifth, 6th, 7th and 8th gear unusable, too high.