Winfried

Hello,

I'd like to know if that bike could be retrofited to use a chain instead of a belt drive.

Can the frame take a chain tensioner?

Thank you.



--
Edit: Apparently, a CT-S510 can't work with a CJ-8S20 cassette joint and vertical dropouts because it'll be in the way :-/



Can a Nexus 8 take an Alfine cassette joint, with its "cable arm" above the chainstay?

mpetry912 

anything is possible. the answer might depend on whether you can find a tensioner that matches mounting holes on the dropout.

be prepared for some R&D

/markp

Dan Burkhart 

No. A cassette joint from earlier Alfine models, 500 and 501 will work, but the later model as shown in your photo rotates the spool the wrong way. New Alfine hubs are high normal as opposed to low normal like the old models and all Nexus 8 models.
Also, your vertical dropouts do not appear to be sliding type, so I am going to guess your bike has an eccentric bottom bracket to tension the belt in which case it would also tension the chain and no tensioner should be required.

Winfried

Indeed, it has an eccentric BB. Since a chain wears (ie.extends/lengthens wtih wear) while a belt doesn't, I just wanted to check if I could avoid touching it and use a chain tensioner instead.

Thanks for the confirmation.

Winfried

This looks awfully like the Alfine CT-S500 chain tensioner used with a Nexus (or old Alfine) cassette joint (source):

But it looks like there's a derailleur hanger connecting it to the frame, which might not fit on my bike.



Or a Blackspire Stinger, or even a chainstay-mounted tensioner:

79pmooney

Chain tricks you may or may not be able to use. 1) Run 1/8" cogs if possible. No drawbacks. They wear longer. The chains are harder to throw off, allowing more slack and easier setting of chain "tension". (In quotes because a single speed/IGH/fix gear chain should never have any tension whatsoever except from pedaling effort.)

1/8" chains exist in the real world of industrial machinery. So 2) things like 1/2 links (male at one end, female at the other) are readily available in any hardware store. I've never used an eccentric BB but I'm thinking that the ability to make 1/2" chain adjustments instead of 1" could make life easier. (If you use a 1/2 link, you cannot run a narrow-wide chain but in my many years of fix gear riding with 1/8" chains, I cannot see that you would ever need to if you have the ability to set the chain slack properly.) The Izumi ~$25 chains are excellent, last a long time and are made with pins that protrude enough that you can drive and re-drive them in complete confidence with any ordinary but reasonable quality chain riveter.

FBinNY 

Before doing anything you need to know that belt and chain sprocket teeth are cut differently.

So the answer depends on whether you can find chains sprockets for both crank and hub.

Winfried

Thanks for the infos.

I'm concerned with tension because, unlike a belt, a chain lengthens with wear, and I'd rather avoid having to re-adjust the eccentric BB just for that.

Not sure how easy it really is to find bike chains with half links. I might have to use a regular chain and see how it goes. And make sure the chainring can work with a 1/8" chain — Nexus rear cogs work with 3/32" chains, so I guess they also work with 1/8".

With luck, the Alfine CT-S510 might work with a Nexus cassette joint provided the chain goes under the idler pulley/jockey wheel instead of above.

Dan Burkhart 

You are worrying too much about something that is not much of a problem. The eccentric bottom bracket is an elegant solution for taking up chain slack so why fuss with a tensioner?
I have IGH bikes with vertical dropouts and no eccentric bottom brackets that I have been able to size the chain close enough to function well without a tensioner.Not always possible but I have done a number of builds where it just worked out.
Anyway, if you have a straight chain line, a tiny bit of droop isn’t going to hurt.
Spend some time at a velodrome you will see lots of bikes doing the circle with a bit of visible sag in the chain.
But all that said, adjusting an eccentric bottom bracket isn’t hard.

grumpus

Eccentric bottom bracket is the nicest way to adjust chain slack because it doesn't require any additional moving parts. Ghost chainring is the most amusing.
Go to any BMX specialist.

79pmooney

Industrial half links work just fine with 1/8" chain. (Any Ace Hardware/A-Boy Plumbing. Ask for 1/2" x 1/8" half links.) They are harder to find in bike shops and usually only the shops that specialize in fix gears. I don't think any bike chains come with half links and I suspect that is true for the industrial chains as well. But industrial half links and quick disconnect links are readily available because industrial - if it breaks, you gotta be able to fix it! (The quick disconnect links are clunkier than bike specific ones so sometimes clearance is an issue. The ones I've used had longer pins and cotter pins on one side. Open ocean marine hardware secure, not just pretty bicycle secure. And $5 or less anywhere. The fix gear in my avatar photo has run real miles - and at least one Cycle Oregon - on an industrial half link and disconnect. Maybe even in that photo.)

Yes, you can run 1/8" chain over 3/32" cogs/chainrings. Just not the other way around.

grumpus

There are bike chains that are nothing but half links from one end to the other.

veganbikes

I would never want to run a chain instead of a belt if the bike was set up to run belt drive. It is lower maintenance and longer wearing.

However if I wanted to run a chain I probably could do that on that bike just by getting the chain length right and wouldn't need a tensioner. You shouldn't need to really adjust the B.B. unless you really wear down the chain significantly and don't replace it but that is just a matter of proper maintenance. However I would rather just have a belt drive save 4-6 chains potentially and no lubrication or cleaning and less weight.