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I am hoping you band of merry men can help me ? I am currently running Shimano 105 on my road bike which has been good to me, however whilst tackling a particularly tough climb (the rake) last night the gears started to slip whilst in 1st gear (granny ring). This only happened whilst the chain was under heavy load as later on in the ride under less load it was fine. Any ideas how to fix this ??
The fix is really easy!
MTFU and stop using the granny ring! 😆
Seriously speaking: you didn't specify how old is the crankset. Maybe it's time to replace the chainring?
Chain and cassette has done approx 800 miles
New Chainring, New Cassette, New Chain
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New Chainring, New Cassette, New Chain
You could try adjusting the rear derailleur first in case the cable has stretched - unlikely though as it's only just started happening.
I'm not clear what gear you're in... 'Granny' usually refers to the smallest of a triple, often with few teeth (e.g. 24) If you're on 105, is it a double or triple? Are you in the largest sprocket (back) when in the smallest chainring (front)?
Yeah easy gear i should've said
Still non the wiser, is it a 3x9 drive chain and it's only slipping on the smallest of the 3, I.e the granny regardless of what rear sprocket you are using ?
Seems unusual for the granny to wear before the chain, the cassette or the middle ring.
Unless the granny is damaged, unlikely as it's shielded by the larger rings, at 800 miles the chain is almost certainly shot, possibly the rear sprockets /cassette too, seems odd it would only slip on the smallest front ring. Any chance of some photos?
Wildcard answer is that the gear cable guide under your bottom bracket is gunked up, causing cable pull when the frame flexes slightly while climbing.
You only notice while going up a tough climb, since I am guessing you are climbing standing up.
Lube the cable and see if the problem goes away.
Check chain length as well. If you're using a three ring chainset and cross gearing it (small ring at the front, small sprocket(s) at the back, then you will have a lot of chain flapping around. This can lead to slippage, especially if you have a bit of drivetrain wear.
Another thing is how stiff the frame is.
Probably the best answer is to take it in to a *good* local bike shop and explain the situation if you're unsure. It's the sort of problem a bike shop that knows its onions does really well.