It doesn't make any sense to me. Is the Problem in the chain? Or is my Chainring fucked?
Chain tension is changing depending on crank position
byu/yfubaka inbikewrench
by yfubaka
It doesn't make any sense to me. Is the Problem in the chain? Or is my Chainring fucked?
Chain tension is changing depending on crank position
byu/yfubaka inbikewrench
by yfubaka
23 Comments
Bad tolerances on the chainring so it’s not quite centred
I’m not a professional bike repair guy. But my common sense tells me that either that chain ring is oval, or magic is happening.
Otherwise, I’m clutching at straws like maybe parts of the chain have seized up links. So it appears to be a tension issue but actually it’s freedom of movement of the links.
Chainring never truly center in the spider so there’s variance. Well known phenomenon. Can’t be avoided. Adjust chain tension if it’s too tight around the tight spot in the pedal stroke.
Either chainring or cog is faulty but most likely it’s chainring
Its totally normal. You’ll pretty much always have a high and low tension point on SS or fixed bikes. A cheaper chainring may be worse then a real nice one.
chainring, crank, or BB spindle are the cause of this, and this is especially common with cheap parts. nothing you can do about it except swap things out and see what the cause is… or ride with track slack and forget about it. since you’re not riding fixed, chain tension is a little less relevant so you can afford some degree of slack over riding with a fixed cog.
People spend a lot of money for chainrings that don’t do that, don’t worry it’s normal, just set your tension where the chain is most tight.
On motorcycle this is also happening. Chain elongation is not uniform, chainring manucafturing tolerances are also not that precise (or it would be more expensive).
That is why we usually checking the chain tension on multiple wheel positions/chain links.
If it is stiff and loose st a specific crank position it means that the front chainring is offcenteted.
Normal. Try loosening your chanring bolts and and lightly snug up two of them. Set the chain tension and cycle the cranks a few times. Perhaps the tiny amount of play in the chainring interface will allow it to find concentricity. It probably won’t work, but it doesn’t cost anything but a few minutes to try.
This is a very common thing with motorcycles, It’s usually due to a worn chain and/or sprockets. The only diagnostic is to visually inspect if the big chainring is concentric. Put a zip tie on the frame with the end sticking outwards to check. If it is concentric, then your chain is probably bad. TBH that chain looks to be of subpar manufacturing quality.
Thank you for all the replies! 🙂
I’m glad its normal and not a serious issue.
I’ll upgrade the Chainring/Crankset in hopes of fixing it in the future.
That’s normal. Round chainrings are slightly ovalized.
Go too the Sheldon Brown website. There is a good reference there for centering chainrings amongst a lot of other stuff.
[Sheldon Brown ](https://www.sheldonbrown.com/no-derailers.html#centering)
Crappy chainrings exaggerate this issue. If it can be not “too loose” when maintaining functional tightness, then it is acceptable. If your chain wants to fall off, get a more precise ring.
What you need do is set the crank to the tightest position, loosen the crank bolts a bit a squeeze the chain both sides towards the chainstay. This will twist the chainring on the spider a bit to its loosest point. Rinse and repeat until happy. It won’t be perfect but should be a lot better than that.
Losen the bolds a bit if the chainwheel,turn to the tight spot and tighten two bolds and see if the difference isnt that big,repeat till your satisfaction
Chainring’s probably just slightly warped or off-center on the spider. Set your tension at the tightest spot in the rotation and you’re fine. If it’s really bad, a quality ring will minimize it but you can’t eliminate it completely.
Used to experience this on motorcycles- chains always wear to a tight spot; is it a new chain?
Well I have learned something today, my guess was the bearing being slightly out but it appears this happens on all fixed speed bikes.
Glad you got your answer op.
If u have the right chainring could do half link chain
You can center the chainring on the crankset to minimize tension difference.
Normal for single speed bikes
Biotech chainring perhaps ?