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Internal Hub users, I have a tensioner solution!

LI-ghtcycle

10 MW
Joined
Aug 29, 2009
Messages
3,818
Location
Oregon City Oregon
So many of you know about my recent mid-drive project, and it has only been tarnished by one glaring detail: the chain tensioner.

When I was using the smaller bicycle chain sprocket, it wasn't as difficult to do this, however with the new larger 95T #25 sprocket, it has decreased the margin of error to almost nothing, and using a typical derailleur (I am prevented from using some of the better kinds because of the restrictive space in the back caused by the NuVinci linkage) has meant it has never quite behaved as I would like with about a 1/16th of gap between motor and pedal chains.

So last night someone mentioned to me something about a special automatically adjusting chain tensioner Vision sold to the dealers to demo their products allowing for different sized people to ride the same bike with out lengthening/shortening the chain.

I then realized that I could use an old short-cage derailleur to do virtually the same thing, and it solved 99% of the issues I was having! :D

For the last 1%, I used an old recumbent bike trick, using 1/2 inch irrigation (poly) pipe to act as chain guides to help keep spacing just so where the chains are near each other to keep a healthy gap between them, and surprisingly, the pipe makes virtually no noise! :shock: :D :D :D

Here are some pics:

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There might be some high-dollar off the shelf tensioner, but this is something you can buy at most bicycle shops, and would be cheap and available often as a used part. 8)
 
It's an interesting derailer--I've never seen one quite like that before. Does that say "ATP" on the tab? And "Simplex" on the label?
 
amberwolf said:
It's an interesting derailer--I've never seen one quite like that before. Does that say "ATP" on the tab? And "Simplex" on the label?

Yes, the ATP metal bracket is stock for the Vision, and it's normally vertical, it's just slanted back a bit to accommodate the simplex derailleur that is bolted to the hole I drilled and tapped. It has a shoulder in the body of this vintage derailleur so I just removed the tab that goes over the axle and bolted to the ATP bracket that normally just holds a roller to hold up the chain.
 
Nice to see you solved the problem. I use the "Terracycle" tentioner solution, and also use the poly water pipe chain cover.

Over 7,000 km and still works perfect, Terracycle will custom adapt anything you want because they seen it all before. I did it over the phone and the price was fair, but not cheap.
 

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looking for a chain tensioner for #219 chain

http://www.seekpart.com/company/61196/products/2011930105150157654984556.html

6528744871_c8cb594b9d_z.jpg
 
jmygann said:
what size chain on the motor ?

It's #25, but I think in the future I will try #219 heavy duty cart chain. The #25 works, but it has stretched quite a bit, never broken, so I guess it's holding up ok! :lol:
 
jmygann said:
looking for a chain tensioner for #219 chain

http://www.seekpart.com/company/61196/products/2011930105150157654984556.html

6528744871_c8cb594b9d_z.jpg

Interesting tensioner, any idea how it bolts up?
 
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