I’m trying to sort out the tensioner on the Trivelox three speed gears on a vintage tandem.
It’s an odd system where the chain stays in line and the sprockets move across the hub on splines.
The tensioner part was missing when I bought it. it had been bodged with an old Simplex derailleur, but didn’t work.
I’ve now bodged it with a Rohloff tensioner, which probably would work, except that the cage sides are too close together for the 1/2″ x 1/8″ chain that it needs for the thicker chainring and sprockets.

Is there a single speed tensioner around that looks anything like this ?

As you can see, there are at least two different types. I’m not sure which I want.
Does anyone make a tensioner that looks close to either of those and, most importantly, will take a 1/8″ chain ?

is the Rohloff DH tensioner a better option..?

will that do it?

(http://www.sjscycles.co.uk/tensile-single-speed-chain-tensioner-prod28666/)

Can you not just use an old rear mech? Brake cable with the stop left on pushed through the barrel and clamped to hold the mech in the right place?

Am i right in thinking you want a mech that provides constant tension, but allows the chain to move sideways across the sprockets?

If so, I’d probably be tempted to go with a DMR simple tension seeker, which IIRC has quite a wide guide wheel?

The long version of Tensile one looks exactly what I’m after.
I can bolt it on through one of the holes in the arm and adjust the angle and position a lot more easily than using a rear mech.
The only potential problem is the width between the cages.
http://www.tartybikes.co.uk/sprung_tensioners/tensile_single_speed/c48p10421.html?tab=reviews#box
I might have to buy a KMC K710 if my existing 1/8th chain is too wide overall.

The DMR, or any other single pulley tensioner, won’t work. It needs to hold the chain in line and needs to be spring loaded to allow the chain length to vary depending on which of the three gears I’m in, it just doesn’t need to move sideways.

I am using a Yess tensioner on my full suss SS and it works really well, not cheap but does the trick.
http://www.yesspro.com/

Maybe if you get your hands on a Cyclo or Resilion derailleur you’ll be able to use their arms. They’re built for 1/8″ chain.

It may be worth trying Hilary Stone

Thanks, epicyclo. I’ve been searching for all sorts of vintage bike stuff recently, yet somehow missed that site up until now.
Those derailleurs start at about twice the price of a modern tensioner and it would be a shame to cut up something that rare to improvise my gears.
They have got 1/22 x 3/16″ chains though, which answers my other question today.
I now need to check my chainring with a vernier, as I’m not sure now if it’s 5/32″ or 3/16″.

No idea how much that Tarty Bikes tensioner is Graham but take a look at the very similar Superstar version. I’m using one on my s/s f/s Hooker.

Thanks mamadirt, that Superstar one does look very similar to the Tensile one, but £10 cheaper.
Any chance you could measure the gap between the plates for me please ?
I’ll start another thread anyway, in case your not able to at the moment.

The Yess one doesn’t seem to be available in the UK, at least, not the two pulley one that I need.

The Rohloff DH tensioner looks exactly the same as my standard one, apart from the length of the bar. I don’t suppose it’s any wider.

Can you not just space the cages out on the ‘hoff tensioner?

Not easily. The top pulley sits on an extension of the main pivot shaft and is retained by a circlip.
It’s not just a matter of using washers and longer bolts.

Graham, the gap between the plates is a touch over 10mm – plenty of room for an 1/8″ chain (I’m running a 9 speed chain at the mo’ and it looks lost) – mine’s the shorter version btw. I’ve spaced out the jockey wheels and used longer bolts on singleator copies before now to accommodate 1/8″ chains too.

Thanks, 10mm sounds good. Superstar looks like the one to go for.

I think Bromptons have a twin sprocket on a Sturmey hub, with a tensioner that moves sideways to shift it.

Here we go. Only a short test ride solo so far, but it seems to be working OK.

Low gear.

Low gear. “Cassette” to the right, chain in line.

High gear.

High gear. “Cassette” to the left, chain in line.

It’s not ideal. It could do with the cage sides extending upwards to help hold the chain in line as I shift gear. As it is, the chain can get pushed off the side of the top jockey wheel.
Considering it’s 80 years old and was only in production for a few years before being superseded by a more conventional derailleur, I don’t expect too much refinement.

The gap between the cage sides is wide enough for the 1/8″ chain, but the jockey wheel is obviously made for a narrower chain, which allows the chain to sit over to one side and rub the cage, which makes it a bit noisy

Graham

Im intrigued. What actually pushes the chain off a sprocket as the ‘cassette’ moves. The cassette doesn’t seem to move very far and I can imagine how it might work dropping from larger cogs to smaller but not the other way.

It’s probably just my lack of imagination.

It’s a bit primitive.
Mine is the earliest version with a selector fork between two of the sprockets, operated by the cable you can see running along the chainstay.

Not my bike, but this is what it looks like with the wheel removed. This one also has the correct jockey wheels with full height teeth, which would probably help with chain retention.

That’s fascinating! I’m currently (im)patiently awaiting ye olde Schwinn cruiser from USA with a back-pedal operated dual speed hub – should be interesting. Glad the Superstar tensioner did the job.

Fascinating and now got it (I think). Couldn’t see the selector fork on yours. Must require a good shove to go up the box.

Vintage Schwinn sounds good. It’ll be nice to see something unusual like that in the UK.

Not so much a good shove, more a slow, gentle push, hoping it doesn’t drop off the jockey wheel before it shifts.
We’ve been for a proper two up test ride in to town and back and gave up trying to shift down on the move in the end. Going up the gears is OK, but we had to stop and move the chain across by hand to get low gear.
I’ve been looking at pictures on the web and I think mine’s been assembled wrong. I’m going to turn the springs around to get more travel and see if that helps.

Another question about tensioners first.

Can I get jockey wheels with full height teeth like a sprocket ?
Does anyone make them ?