https://www.reddit.com/r/bmx/s/HEIv2NoHmm
Reposting with a video. No matter how much I adjust it, I have a spot so tight I can't pedal, and the rest is so loose I'm afraid the chain is going to fall off. I measured the chain to the exact link for length compared to the old one. It's a complete bike. I replaced the chain with an exact copy. I have no idea what to do now. Please don't just say pull the wheel back, I've literally been doing that exact thing for weeks lol.
by hairlesspet3
15 Comments
I just pulled off both cranks and checked the spindle, it’s not bent. The sprocket is brand new only got one ride in. So idk lmao, I’m about to chuck the thing because this is so frustrating. Having a lot of trouble with a really simple thing.
https://m.youtube.com/watch?v=tV2wVNlTNLw&pp=ygU9SG93IHRvIHByb3Blcmx5IGluc3RhbGwgYm14IHNwcm9ja2V0IHRvIGVuc3VyZSBwcm9wZXIgdGVuc2lvbtIHCQn8CQGHKiGM7w%3D%3D
Something has to be wrong either with the sprocket, or the installation of the sprocket. No other answer
Double check there isn’t a tight/stiff link in the chain.
Remove the chain and take a look at the sprocket as you rotate the cranks. If there’s no issue with the spindle or spacer there’s something wrong with the sprocket.
Did you put a little adapter/spacer between the sprocket and spindle? The sprocket is off center causing the random chain tension.
Another trick you can do (but it’s no substitute for a missing adapter/spacer thing!) is get the chain to the tighter spot and loosen the sprocket to crank bolt. Backside of the sprocket usually. Pedal one or two revolutions with it not tightened. How is it?
You can then get it to the tight spot, squeeze the top and bottom of the chain together, hold, and simultaneously tighten that sprocket bolt.
Seems like your spindle is bent or the back wheel is on crooked.
I have successfully rounded off my fucking crank spindle bolt. I’m having a really bad time.
Either the chain has a tight link or the sprocket isn’t centered there’s nothing else that’ll cause this
If the previous front sprocket/chain combo was doing the same thing, and the new sprocket is also causing issues, it’s probably not the crank side. Maybe take the chain off, and check the rear freewheel/freehub for issues when you either freewheel it backwards while the wheel is still, or spin the wheel and check for a problem?
Only way to really get rid of this if you get spline drive sprocket had this problem for a long while if you have a sprocket that bolts on it will always have some tension in the side where the bolt is. Give it try with a spline drive sprocket and then give it a try with a bolt drive sprocket.
Maybe a chain link or two are far too tight not allowing it to go around the sprocket. Take chain off and see if there are any tight spots within the links.
Do you have the correct size adapter on your sprocket/spindle? The hat washer needs to fit snug on the spindle and snug in the sprocket bore. The adapter “hat” end goes towards the bottom bracket behind the sprocket, there should be nothing between the crank and sprocket. then any spacers needed behind that to create as close to perfect chain alignment as you can get.
Another thing, if the sprocket bore is resting on the splines, on an 8 spline crank(even 48 spline for that matter) it can cause the sprocket to shift around. I use 3 piece cranks like a 2pc and never take the drive side off. I tighten the end crank bolt to where my sprocket rest on the smooth portion of the spindle and tighten everything down. If my cranks need to come off I take off the non drive side and pull it through.
Really seems like a bent sprocket to me. Very odd
The sprocket is new but did you also replace the chain?
If your old sprocket had damage making it out of round the chain may have stretched over time as a result of the damaged sprocket, & now you have a new perfectly round sprocket the tight spot is more apparent.
When you replace an out of round sprocket you also should always replace the chain. Not just because of the uneven chain tension, but because It could damage your new sprocket making it also become out of round.