I’m somewhat new to working on my bike.
I got a new bike about 2 months ago. After riding it for a bit I readjusted my rear derailleur (limit screws & indexing) since it was needed as it was noisy and skipping gears.
It rode very well and I was happy with the rear derailleur adjustment for my first couple rides after. Then I noticed when I was standing up and pedalling hard down, only in the highest gear it would clunk forward. I tried slightly adjusting the h-screw and turning the barrel adjuster clockwise, but it is close enough that it maxs out.
All the other gears shift and ride fine under pressure, it only happens under high pressure (standing up pedalling) in the highest gear.
Should I readjust my rear derailleur through all the gears again ? Perhaps something to do with my chain (too loose/too long) ?
Any ideas or help is appreciated, as I said I’m new to this and I’ve read a lot of forum posts but can’t quite figure it out on my own.
Thanks.
Clunking forward when in highest gear under pressure?
byu/Impressive_Moment_12 inbikewrench
by Impressive_Moment_12
15 Comments
Worn ratio
Idk but this is likely a symptom of a wore down cogs, although I might be wrong since the bike is still new. But try to double check the tooth of the cogs. If it is slanted or it looks like it is sharp (like shark’s tooth), it might need replacing. Although Im not sure about my answer and also sorry for my bad english😅
Make sure your chain length is right and your b screw is good. Check your free hub too. Looks like a worn cassette cog but the bike is new
Cassette/chain worn out
B tension is too tight
Since it’s new we should be able to rule out worn parts. Makes me think you have a stiff link. Search youtube on how to identify a stiff link and how to remedy it. Spoiler alert; it’s super easy.
You need to ensure the limit screw for the low adjustment is not in too far. When the chain is in the lowest (smallest) cog, ensure the chain is aligned. There might be a set screw to adjust the forward/backward, and that might need to be backed out so there is sufficient chain to cog contact.
So moving the video as slowly as I can, it almost looks like the chain jumps from the 2nd smallest to the smallest cog? Are you sure you’re in the smallest cog when it jumps, or is it a forced shift under pressure?
Sometimes, it’s a sticky master link.
In the video it looks like your right foot is off the pedal which leads me to believe your entire weight is on that left pedal which is a lot of force. Putting that much force at slower speeds on the highest gear is going to result in skipping no matter your adjustments.
Sure, the limit could be off but you’ve adjusted it. Your tension could be off but you said you’ve adjusted it. Process of elimination, considering your adjustments are correct, means the issue lies elsewhere. Chain wear? Cog worn? Riding incorrectly?
Yeah check all your screws and cable tension first. Make sure they are as good as possible. If it still happens, then you are looking at a new cog or cassette, chain, and possibly chainring.
Shift your gear man. You literally have all of your weight on 1 foot pressing down (your right foot is off the pedal) in your hardest gear while going walking speed.
Maybe ratcheting pawls in hub. Or rear cassette
I can’t tell from the video, it’s too ar and low resolution.
But here’s what it might be:
B-Screw might be adjusted wrong so b gap is off so pulley is hitting the cassette cog, resulting in skipping and drivetrian jamming up. If so just tightness the B-screw and shift down, adjust when needed, and shift to 2nd gear, make sure the b-gap is around 3mm.
Is it the cassette that moves? If so freehub mechanism might be skipping, be broken or need of service.
Can be skipping chain due to mismatch due to lot sof era Ron cassette but new chain, or both chain and cassette are worn out.
Or chain has a stiff link.
Vent cassette cogs, teeth.
Unrelated but mus tbe said:
The bad:
Bad pedalling technique, as the foot pints down.
Those shoes are too flexy and thin, dangerous to rid win, pedal
The great:
Foot position, midfoot position so that’s great for stability.
Pedals are way too short, no proper support, I reccomend Pedaling Innovations pedals, they support the arch, for best price buy on independence day sale.