Why not Flip Flop Hub?

[thewump]

I'm looking at a couple of potential build projects and at the out of the box sprocket clamp / spoke hub assembly and wondering if anyone has uses a flip flop hub instead?

Flip flop hub with a freewheel on one side, a large fixed sprocket on the other would be ideal.. Just not sure if you can get big sprockets that fit the standard fixie hub threads.

Thoughts?

Just for fun, here are the two bikes I'm looking at motorizing:

K

 

[Motopecane]

I think you probably answered your own question here. I don't think you can get sprockets large enough that thread on. also you wouldn't be able to get one that is for a #41 chain. It's what mopeds and small engines use. A regular bike chain would be way too weak. Also if you flipped the wheel so the freewheel was on the right (like normal) the fixed side threads would then be going the other way. So essentially even if you could get a gear that would work the engine would thread it right off instantly...

 

[Dowie Soetenga]

That's what I used. I bought a hub that's threaded on both sides from Spooky Tooth. I used a #35 chain for the primary drive, and a bicycle Z510 chain for final drive. I did a ton of research on chains. You can use #41 if you want, but you don't have to. A Z510 chain actually has a really high tensile strength rating. Way stronger than a standard 410 chain. A Z510 chain also is anti-stretch. I've been running a 100cc 2.5hp four stroke motor with no issues so far. I'm using a 44T sprocket on the rear.

 

[Beau]

I have used disk brake hubs for gas bikes. You can drill out the sprocket you get with the kits to fit the bolt pattern on the disk hub. I had a machine shop do it for $20. The problem is you have to cold set- you frame and widen it to accept the larger hub spacing. But that usually good because chain clearance can be an issue on the engine drive chain (too narrow).

 

[Motopecane]

well you proved me wrong still wouldn't the threads on the other side of the flip flop hub be backwards?

 

[cobrafreak]

My Indian has a triple treaded hub. The standard thread for the freewheel is on the pedal crank side. One the left side of the crank (engine side) there are two threads. The inner thread is reverse threaded for the spin-on chain wheel. The outer thread is standard right hand thread for the spin on band brake drum. Here is a link:


http://www.bicycle-engines.com/solid-sp ... p-298.html

 

[Sinner4]

well you proved me wrong still wouldn't the threads on the other side of the flip flop hub be backwards?

Your right, start up the gas engine and the sprocket on the other side will spin off in a blink of an eye.
It would be a great Idea if some one builds them. Patent the idea and become a millionaire in the blink of an eye.

 

[Motopecane]

My Indian has a triple treaded hub. The standard thread for the freewheel is on the pedal crank side. One the left side of the crank (engine side) there are two threads. The inner thread is reverse threaded for the spin-on chain wheel. The outer thread is standard right hand thread for the spin on band brake drum. Here is a link:


http://www.bicycle-engines.com/solid-sp ... p-298.html

the fixed gear hubs he is asking about though have a double threaded system but the fixed gear cog threads on standard thread and I honestly would not trust a lock ring under the torque of a motor.

 

[cobrafreak]

My Indian has a triple treaded hub. The standard thread for the freewheel is on the pedal crank side. One the left side of the crank (engine side) there are two threads. The inner thread is reverse threaded for the spin-on chain wheel. The outer thread is standard right hand thread for the spin on band brake drum. Here is a link:


http://www.bicycle-engines.com/solid-sp ... p-298.html

the fixed gear hubs he is asking about though have a double threaded system but the fixed gear cog threads on standard thread and I honestly would not trust a lock ring under the torque of a motor.

Neither would I. It needs to be a left hand thread or you will find out what can happen :shock:

 

[Motopecane]

So I guess the answer to your question is you probably shouldn't. Flip flop hubs were designed with two right hand threads because, well you can flip the wheel around to go from fixed to freewheel. It works because your only using one side at a time.

 

[Beau]

People do run the fixed side on the left sometimes. So they have left side drive. It's actually not that crazy on a PEDAL bike. It no different than back pedaling or skidding to stop.

I would not do it on a gas bike though.

They also make hub with left side drive for BMX bikes. ACS makes a freewheel called the South Paw. But those hubs are hard to find now.

 

[thewump]

well you proved me wrong still wouldn't the threads on the other side of the flip flop hub be backwards?

No. For a flip flop hub one side is designed for a fixed gear.. and you use that to put pressure to move forward AND brake. To keep the cog from spinning off this side has two thread areas. One for the cog and a reverse one for a fixing ring.

K

 

[Motopecane]

well you proved me wrong still wouldn't the threads on the other side of the flip flop hub be backwards?

No. For a flip flop hub one side is designed for a fixed gear.. and you use that to put pressure to move forward AND brake. To keep the cog from spinning off this side has two thread areas. One for the cog and a reverse one for a fixing ring.

K

Haha yes to clarify I know that. If you would have read the entire thread you would have noticed me saying that I wouldn't trust a lock-ring on a motorized bike.