A long strait chain

[paul fellows]

Here is an idea you might find useful.

Instead of having the chain zig zag over idler pulleys, to control it, have it pass through a long chain tensioner.

Take a length of PVC tube, about 8 to 12 inches shorter than the length that the chain needs to be. Soften and thin down the back end of it, so that it dose not interfere with the back wheel when in low gear. Put 4 idler pulleys / sprockets on it, 2 front and 2 at the back. Fit the chain to the bike, passing it both ways through the tube. The tube floats on the chain protecting it and you, and is not in any other way connected to the frame. A long strait chain that dose not flop about.

 

[classic33]

Black water pipe. Friction does build up and should the chain take anything into the tube, it can be hard to remove.

 

[paul fellows]

true about dirt problem, i had not thought of that. with regards to friction i am thinking, the idler sprockets sit on the chain and the pipe is supported & held in place by them. reading my post i was not very clear was i.

 

[Drago]

https://www.flickr.com/photos/38236150@N06/5619705671

 

[cookie32]

I run tube and one pulley. I started with all pulleys running along the frame but the resistance was a lot higher. It's about as good as it gets like this. The tubing is 15mmx2mm. I just picked up a new 2m tube at B&Q today for under 4 pound.

tomahawkk side view

• cookie32
• 18 Aug 2015

 

[classic33]

true about dirt problem, i had not thought of that. with regards to friction i am thinking, the idler sprockets sit on the chain and the pipe is supported & held in place by them. reading my post i was not very clear was i.

I learnt about things being pulled into the pipe the hard way. I ended up cutting the pipe, rather than damage the chain.

 

[starhawk]

On my trike the chain are in a tube most of the way around, the driving bit has a small opening on the middle when passing over an idler pulley but the returning bit is in a tube all the way from the front chain wheel to the rear cog and that is the standard so why complicate things?

 

[stuee147]

do you or would you not get more noise using a tube rather than pulleys iv found even different pulleys can make more or less noise than others ?
in not saying i disagree with the idea of tubes i would like to use them maybe on my next one but i just think the friction and noise are more of a disadvantage than any advantage it may give. i find that forward planing and adjusting and there shouldn't be to many pulleys i only use 2 pulleys on my trike because i adjusted the seat brackets to allow for a straighter chain line.

 

[Sandman-bm]

My latest trikes ( identical) both are fully tubed and one pulley, so far I have not noticed any excessive drag but certainly a reduction in chain noise over the pulley, this is evident when I use the go pro mounted on the trike, my other trikes ,using exactly the same design pulley transmit chain noise to the cam at a horrendous level
regards
John.

 

[paul fellows]

Chain tensioners, or there pulley based equivalents have been around since the industrial revaluation. They are used to maintain the drive tension in line-shafting etc.

the idea of having 2 of them support the chain guide seem like a sensible idea to me.

The use of a tube as the chain guide can cause problems, so an open chain guide might be better.

The advantages I see this as offering are:

1) The chain dose not have to be pulled sidewards to pass its self.

B) Because the pulleys / sprockets are not attached to the frame, the chain can follow the optimum line what ever gear you are in.

iii) the extra mass of the chain guide on the chain will make it less likely to bounce around.

 

[voyager]

Whats not broke------ don't try to fix it ...........

Noah lost a unicorn trying to be too smart - that is why they are now extinct .

........................................................................................................................


regards emma

 

[paul fellows]

Whats not broke------ don't try to fix it ........

i could not reinvent the wheel, had someone not invented it first. if you don't like the idea of trying to do things better, by all mean walk every where like your ancient ancestors did.

 

[classic33]

Whats not broke------ don't try to fix it ...........

Noah lost a unicorn trying to be too smart - that is why they are now extinct .

........................................................................................................................


regards emma

Is that why the dog got a wet nose?

 

[voyager]

Is that why the dog got a wet nose?

I believe so

 

[Sandman-bm]

Your concept is interesting Paul,
1: Does it take into account that almost all recumbents, 2 and 3 wheeled don,t have straight line chain runs ? or are we all building them wrong.
2oes your design permit one sprocket to engage with the driven section of the chain at the same time as the return side of the train,if not I fail to see how it can float, any disparity in friction on the rollers/sprockets will move the entire assembly into the chainring or rear cluster if it is not fixed at some point to the frame, ghost rings do this with far more simplicity although not used on trikes
3: Even chains constrained in tubes "flop" from side to side at times, just adding mass does not kill that.
regards
John