Is the tensioner meant to be like this?

[eddie123]

As i Pedal the bike the chain keeps jumping. I think it is to do with the tensioner, whenever it is pushed it doesn’t spring back up and leave the chain loose. Could this be the issue?

 

[eddie123]

whenever I pedal the chain keeps jumping. I think it is because of the tensioner as whenever it is pushed down it doesn’t spring back up making the chain loose. Could I be right is saying this could be the cause?

 

[Pat "5mph"]

You only need to post the question once.

Mod note:
Be nice
Threads now merged.

 

[Biker BoB]

Remove the wheel and spray it with penetrating oil.
Looks like the frame could do with a respray while you are at it ...

 

[Big John]

I had the same 'problem', assuming you have the same tensioner as me and it looks like you do. It's on upside down i.e. it's supposed to push up from the bottom - not pushing down like yours is. Take it off and fiddle with it until you've got the jockey wheel 'outside' the chain instead of 'inside' it. I had to work it out in my head first and then fix it back on. There may be a YouTube vid that'll help but I'm pretty sure it's as I've said. I'll take a look at my bike tomorrow and post a picture which might help 👍

P.S. when it works they're a great little tensioner.

 

[Paulus]

Agreed. Take the wheel out and throughly clean the tensioner, especially at the pivot points. Then spray with lube, wipe off the excess and try moving it. Then if there is no improvement, do it again.
Try loosening the bolt that holds the tensioner to the frame slightly, I have this problem on my Brompton from time to time, and I find that the retaining bolt tightens up and will not let the tensioner release.

 

[Espresso vecchio]

I had the same 'problem', assuming you have the same tensioner as me and it looks like you do. It's on upside down i.e. it's supposed to push up from the bottom - not pushing down like yours is.

I disagree. The majority of tensioners, like the one in the photo, push DOWN, ie the jockey wheel should be inside the chain, and the arm pivots away from the chain stay to keep the correct tension.

If yours was once working ok, as I suspect it was, the cause of the slack chain is either dirt preventing easy pivoting, or it's overtightened at the pivot, or possibly a broken spring. Easy to check, easy to clean, and not much more difficult to adjust the tension with an Allen key.

A few tensioners, usually the much more expensive ones like Surly ones, are supplied with two different mirror image springs, one of which you use, depending whether you want the jockey wheel inside or outside the chain, ie pushing down towards the ground or up towards the chainstay. Pushing-up types are more likely to be used on competition bikes so you can have better chain wrap.

 

[craigwend]

I disagree. The majority of tensioners, like the one in the photo, push DOWN, ie the jockey wheel should be inside the chain, and the arm pivots away from the chain stay to keep the correct tension.

If yours was once working ok, as I suspect it was, the cause of the slack chain is either dirt preventing easy pivoting, or it's overtightened at the pivot, or possibly a broken spring. Easy to check, easy to clean, and not much more difficult to adjust the tension with an Allen key.

A few tensioners, usually the much more expensive ones like Surly ones, are supplied with two different mirror image springs, one of which you use, depending whether you want the jockey wheel inside or outside the chain, ie pushing down towards the ground or up towards the chainstay. Pushing-up types are more likely to be used on competition bikes so you can have better chain wrap.

OP only popped in for a day...

 

[Big John]

Here's my tensioner, which has been on the bike for years and works perfectly despite Espressos 'disagreement'. Before anyone remarks on the state of the bike (as is usually the case on here) this is a well used 'pub' bike and purposely kept unpimped. The smarter it looks the more likely it'll go walkies. I will, however, agree that most are fitted on the inside of the chain pushing down but obviously this one is fitted pushing up.

 

[Espresso vecchio]

Cool. No problem with you on my part Big John. Nothing wrong with your way at all but it is in a very small minority. I've never seen a factory-fitted tensioner pushing up.

My point was only that the vast majority of tensioners on single sprockets like this apply their tension away from the chainstay.

 

[Ajax Bay]

OP only popped in for a day...

It's tricky isn't it. We've had another newbie just now ( @chibbz_2997 ) who does a 'John Nott'. @vickster was super-optimistic/charitable.
I suspect these people have a 'problem': blast the same message on a number of sites and maybe see the answer on one.
But hopefully, in the future, when someone can't (in this case) solve a tensioner issue, a 'search' will find this.

 

[ColinJ]

Cool. No problem with you on my part Big John. Nothing wrong with your way at all but it is in a very small minority. I've never seen a factory-fitted tensioner pushing up.

My point was only that the vast majority of tensioners on single sprockets like this apply their tension away from the chainstay.

My Planet X 'Doofer' tensioner was supposed to pull the chain down but I had problems with the chain coming off on bumpy roads. I fiddled about with the Doofer and got it to push up instead. No dropped chains in thousands of kms of riding since then!

I think my problem might have been that I was recycling sprockets from old cassettes. They were half-worn, and (obviously) designed to allow the chain to come off when gear-shifting. A proper singlespeed sprocket would be designed to retain the chain!

 

[Ming the Merciless]

Here's my tensioner, which has been on the bike for years and works perfectly despite Espressos 'disagreement'. Before anyone remarks on the state of the bike (as is usually the case on here) this is a well used 'pub' bike and purposely kept unpimped. The smarter it looks the more likely it'll go walkies. I will, however, agree that most are fitted on the inside of the chain pushing down but obviously this one is fitted pushing up.

Makes sense at that’s what derailleurs do with the top jockey wheel. Same principles.

 

[ColinJ]

Makes sense at that’s what derailleurs do with the top jockey wheel. Same principles.

That's what I decided... Better to have the tensioner helping to wrap the chain round the sprocket rather than helping to peel it off!

That was with a new chain.

After a couple of hundred kms the tensioner had more work to do...

(I removed the spring from the Doofer and tightened a washer against its body to hold it in the position that I had set it in to take up the slack in the chain.)

PS In case you wondered why a singlespeed bike had 2 sprockets... My first version just had a stack of spacers to fill the spaces vacated by the other sprockets in the cassette. I had the lockring tightened against a spacer. That turned out not to be a good idea! The lockring came loose on a 100 mile Humber Bridge forum ride. Fortunately, I wasn't far from a bike shop where a kindly mechanic tightened it back up for me. After that I stuck a 12 tooth sprocket on for the lockring to bite against.

 

[Yellow Saddle]

My Planet X 'Doofer' tensioner was supposed to pull the chain down but I had problems with the chain coming off on bumpy roads. I fiddled about with the Doofer and got it to push up instead. No dropped chains in thousands of kms of riding since then!

I think my problem might have been that I was recycling sprockets from old cassettes. They were half-worn, and (obviously) designed to allow the chain to come off when gear-shifting. A proper singlespeed sprocket would be designed to retain the chain!

Your method is the superior of the two. By pushing up, you get more chain wrap and better chain retention and wear.