Singlespeed tight spots in the chain tension

Just built up a singlespeed cx bike

All new kit apart from wheels.

Eccentric bb

Shimano grx 1x chainset.

I set the tension but then noticed if I push the crank around there are little differences in tension.

Is there anything I should do or worry about?

Loosen chain ring bolts move to a tight spot aNd tap the chain

This will center the ring with the crank axle an.

Nah, she’ll be reet 😉

Rings are never exactly round, so you’ll get a tight spot occasionally.
Just don’t have the chain tensioned too tight.

What ajantom said. Not that TR is incorrect but chainsets I’ve used don’t seem to have much room for a chainring to move.

What trail rat said. Used to take a few minutes on mine and the boys’ BMXs then you could run the chain without it flapping about (kids BMXs rear sprocket is so small the chain barely clears the stay, made the difference between chain slap or not).

Same here – my chainring is a tight fit onto the cranks so no chance of adjusting it. I don’t know if the out-of-round is in the chainring or the cranks to be fair – it might be in both in which case rotating the chainring relative to the cranks might help to find the best spot.

But that’s far too much faff so I just set the tension to be “right” at the tightest spot and then check that it’s not too loose at the loosest spot. So far so good.

‘They all do that sir’

so no chance of adjusting it. I

Not got a file.

Yeah, agree in principle with TR but in practice I could never really achieve a perfect setup.

Try fitting an oval ring! Probably 1-2cm difference in slack between low and high. Seems to work absolutely fine.

I would try what trail rat says.

But i would also slacken it as if the tiny amount of variation is causing a tightspot i’d want it a fair bit looser.

There is no effeciency advantage from a tight chain. You just want it to not come off.

You don’t need it silly tight. A little sag (track slack) of 0.5cm is fine provided you can’t ship the chain. Anyway you can losen the chainring bolts and tighten them again if you must.

I inherited XTR cranks on mine and its still got a tight spot. I just move it to the tight spot and adjust the tension. It can be surprisingly slack before it slips.

You might also find that the cog moves a bit on the splines of the freehub body causing tight/slack spots.
As above though adjust it in the tightest position. If the chainline is straightish it’ll be fine and won’t come off.

It is something that has always annoyed me. I use a fixed cog (which you would think would be perfectly round) and I have also used a direct mount chainring that was a very tight fit on crank and again you would except to be perfectly round as presumably CNCd or similar but nope, even gone tight and loose spots with that. Guessing chain tolerances may not help as even very, very small differences (not helped by any wear) are going to add up.

It matters more to me than most as I ride fixed gear brakeless so when skid stopping I like as little slop as possible and ideally like the chain as tight and even as can be all the way round.
For riding single speed I would care.

FWIW I’ve always run an oval ring on mine and never lost the chain or had any problems.

Once I saw how slack track cyclists run their chains I really stopped worrying about it – what I’d previously though of as too slack turned out to be on the right side.

Not got a file.

I have got a file – but don’t find it either a good idea or necessary to start filing chainrings and cranks to allow some slop to get the chainring lined up.

@kerley

I ride fixed gear brakeless

Why?

I ride fixed gear brakeless

Why?

Likes breaking the law? Bit of a rebel?

I ride a fixed too sometimes, but like having brakes!

Oval here too for some years on mine. Even that far out of round I haven’t dropped chains except when it’s been out of adjustment.

Well, I did 50miles of canal, road, paths and mud today…worked perfectly…ill just leave it. Thanks guys👍

I used to run the correct tension at the tightest spot. I never threw a chain. I ran a blackspire chainring (which was pretty round from memory) and velo solo bolt cog on my inbred.

Why?

I enjoy it. Why do you ride what ever bike you ride?

But as others have said, the chain won’t come off unless it is very loose assuming the chainlink is good and it only matters if for whatever reason you don’t like ‘slop’ and for fixed gear riding that can be felt more even when just backing off power which to me doesn’t feel as nice as a chain being as tight as I can get away with.

Well, I did 50miles of canal, road, paths and mud today…worked perfectly…ill just leave it. Thanks guys👍

Finally! 😂

Now you can take it for a real ride none of this flat stuff. Get it on the trails thats where the magic happens.

My (what I used to call it when pubs were a thing) pub bike is fixed wheel. Every 6 months or so I tighten up the chain and the lack of slack when braking is as enjoyable as getting into a bed with fresh sheets (also every 6 months or so).

I ride a fixed gear bike with a front brake.

If you prefer to brake the rear with your legs that’s your prerogative but you must have a second brake in case your primary brake system fails.

Haha…well, I live in the west pennines so absolutely no getting away with hills. Thats why I went with 40/19.

I’ve got 2 brakes on mine, as I like to join in with my friends when we have a single speed road ride but I still use my legs to slow down. I guess my 50 years plus fixie riding may have given me bad habits then.

Single speed chain tension not as critical as fixed – 1cm up and down movement on chain is fine plus running it bar tight is just noisy / wears chain and bearings quicker.

markwsf
Free Member
Once I saw how slack track cyclists run their chains I really stopped worrying about it – what I’d previously though of as too slack turned out to be on the right side.

This. The chain on my track bike is pretty loose – that is the norm.

Belt drive for the win.
You may still have the problem but you don’t notice it as the belt is under tension. It is worth checking the belt at different points of crank rotation as you really don’t want to have to buy them more frequently than necessary.

If you prefer to brake the rear with your legs that’s your prerogative but you must have a second brake in case your primary brake system fails.

You can if you want but I choose not too thanks. I have been riding for almost 50 years – the first 15 on trackers and then BMX with just a rear brake (that didn’t really work well if you remember 80’s BMX brakes!) and the last 20 years riding mostly fixed gear with just the rear brake (legs)

Haha…well, I live in the west pennines so absolutely no getting away with hills. Thats why I went with 40/19.

I forget if this is a mountainbike or not. because you haven’t shown us pictures!

thats a pretty heavy gear if you plan going offroad!

Its a cx bike. Mainly commutes 1000ft climbing 60mins each way…and general riding on the road, paths etc. I experimented for a few months with various gears on my geared cx bike.

ah fair enough sounds good.

still no pictures though… thats not how this place works. we help you provide picture of finished beast.

you must have a second brake in case your primary brake system fails.

I choose not too thanks

Sorry, but it’s illegal and dangerous – you need a front brake.

How’s best to post pics these days (free)

If you prefer to brake the rear with your legs that’s your prerogative but you must have a second brake in case your primary brake system fails.

You can if you want but I choose not too thanks. I have been riding for almost 50 years – the first 15 on trackers and then BMX with just a rear brake (that didn’t really work well if you remember 80’s BMX brakes!) and the last 20 years riding mostly fixed gear with just the rear brake (legs)

You cannot stop anywhere near as quickly with a rear brake only. Its illegal and dangerous

It illigal but he only rides on the flat slowly so it’s ok ….ora at least that was the justification on his last attention seeking post about his single brake.

I was told by the esteemed owner of my LBS that track specific rings are rounder than normal ones. Apparently roundness can be an issue, who knew? The Miche track chainset on my track bike is spot on, no tight spots and I run with as little slack as possible.

Why are people so bothered what I ride. I always think to myself I will never mention it again but in this case (chain tension) I felt it was an important point as low chain tension doesn’t feel great when riding fixed and leg braking/skid stopping.

You ride what you ride where you ride, I will ride what I ride where and how I ride thanks.