Belt drive ratio change
- Thread starter camerart
- Start date
They have a few fans now, but are far from popularity yet being only a tiny minority of bike sales.
I don't know what your idea is, but do some extensive checking first. There have been a very large number of solutions for belt drive ratio changing, and many of them patented. I'd be surprised in your idea hasn't been done before.
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I don't know what your idea is, but do some extensive checking first. There have been a very large number of solutions for belt drive ratio changing, and many of them patented. I'd be surprised in your idea hasn't been done before.
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Hi TK,
Interesting link.
Slight subject change. In the 60s when Santa Pod raceway opened, I was watching the big American dragsters. Later in the day they picked cars out of a hat to race each other. A massive noisy dragster against 'The strip duster' (Not the one I just googled) it had a 1920s Rudge engine, with hair pin valves showing, and beat the monster. Very impressed, as you can tell.
C.
Interesting link.
Slight subject change. In the 60s when Santa Pod raceway opened, I was watching the big American dragsters. Later in the day they picked cars out of a hat to race each other. A massive noisy dragster against 'The strip duster' (Not the one I just googled) it had a 1920s Rudge engine, with hair pin valves showing, and beat the monster. Very impressed, as you can tell.
C.
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Hi,
Here's a sequence of images as a kind of animation, showing two different ratios.
Red is the motor farthest away from the viewer, driving 5x gears all the same size in the middle distance from viewer, so all the same revs as the motor. On the green gear is the low gear sprocket nearest to viewer, on the blue gear is the high gear sprocket nearest to the viewer. The light blue wheel is a jockey wheel to keep the chain away from the blue gear nearest to the viewer. The two wooden dowels illustrate the chain. The green gear needs a freewheel, for changing gear.
Hope it's understandable!
Camerart.
Here's a sequence of images as a kind of animation, showing two different ratios.
Red is the motor farthest away from the viewer, driving 5x gears all the same size in the middle distance from viewer, so all the same revs as the motor. On the green gear is the low gear sprocket nearest to viewer, on the blue gear is the high gear sprocket nearest to the viewer. The light blue wheel is a jockey wheel to keep the chain away from the blue gear nearest to the viewer. The two wooden dowels illustrate the chain. The green gear needs a freewheel, for changing gear.
Hope it's understandable!
Camerart.
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Green= low gear Blue = high gear. Both are turning at the same speed, but the blue one has a larger circumference, so moves the Belt/chain farther.
C.
I don't claim to fully grasp your idea, but the Gates belt is notoriously picky for tension and line.
This leads me to suggest the system might work better with a chain.
Well done for a having a think about it.
If no one did as you are doing, we would all still be riding penny farthings.
This leads me to suggest the system might work better with a chain.
Well done for a having a think about it.
If no one did as you are doing, we would all still be riding penny farthings.
Thanks Rob,
Basically, there are two sprockets with different motor/sprocket ratios, in line with the chain, both in gear all of the time, and my mechanism swaps them over.
I'm interested why you don't fully grasp the idea? If it's my 'quick' drawings, I could try again.
Let me know,
EDIT: Hopefully this animation will make it clearer. The Motor )Red is fixed to the frame along with the mechanism (Not drawn) which rotates the gear/sprocket wheels.
C.
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Hi Flecc,
This is just to illustrate the ratio change idea, I was thinking it would be used on electric assited bikes.with pedals, but missed them off for simplicity. If someone was interested enough, they would engineer peddles into the set-up.
C.
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Deleted member 4366
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Hi d8veh,
Why? Please explain more, do you mean while changing ratio? Try to visualise it as any other mid motor drive (with pedals) but just add this into where the motor is. This is only to show the idea. To save me drawing it again with pedals, think of the large sprocket to the right as the pedal crank.
C.
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Deleted member 4366
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I'm looking at your sketch above, where the red blob is the crank. The arrows on it are clearly shown opposite to the sprocket on the chain. You would have to introduce two idlers to reverse the direction, which would then take you up to seven toothed gears, two sprockets and eight bearings, not including the two BB bearings. That's an awful lot for a two-speed change-over.
D
Deleted member 4366
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Right, so, additional to a standard bike's stuff, you need 6 bearings, 5 gears, two sprockets and a chain/belt as well as some sort of change-over and indexing system. Hmmm!. What's the advantage over a double chainwheel with a derailleur?
Now that you've drawn it like that, there's another problem. The sprockets are a different size, so their centres from the centre of rotation of the change mechanism need to be different, which then means you need different idlers. Have you drawn it all out and calculated the ratios?
Now that you've drawn it like that, there's another problem. The sprockets are a different size, so their centres from the centre of rotation of the change mechanism need to be different, which then means you need different idlers. Have you drawn it all out and calculated the ratios?
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Won't you have a problem with maintaining a constant belt length, or are you going to add a jockey tensioner?
Aren't you trying to solve a problem that doesn't exist? Why not just fit a double chainwheel?
Aren't you trying to solve a problem that doesn't exist? Why not just fit a double chainwheel?
D