I fitted for the first time a new rear cassette chain front middle ring yesterday, when I was out today if I was in granny ring and on steep hills the chain would jump, I have just looked at and if you don’t put pressure on its ok, but as soon as you put more force on the pedals it try’s to ride off. What have I done wrong, never had a problem when in granny ring before I did this, the chain I just cut to the same length as my old one, ( not sure if that’s right) go easy on me!

More likely it’s skipping on the granny ring – if the middle / cassette & chain needed replacing the granny ring probably also needs replacement as it all wears as a set.

Try a new granny ring!

What was the condition of the chain and ring you removed? If in poor condition the chain wears into the Cain rings and if you don’t change the whole set you have a fresh chain on a worn chain ring and can have problems lie you’ve described.

also check rear mech alignment

Probably a mismatch of new chain/old ring, you could try turning the granny ring backwards if it’s not got counterbores for the bolts to see if it works as only the trailing edge of the teeth wear.

Would a worn granny ring affect the rear cassette? I think the rear cassette was around 7 months and the chain was a couple of months, also how would I check rear mech alignment? I hate gears but I am determined not to go to a shop to get it done

Alignment or bent mech (I guess the same thing)

I think the assumption is that if it’s only happening in the granny ring, then that’s where the slippage is happening. If it’s definitely at the rear, i’d get a shop to use an hanger alignment tool on it, you can do it by eye, but not accurately, and some set ups seem to be far more fussy about mis-alignment than others.

Thanks everyone for your help, I am going to go through everything tonight, I am also going to order a granny ring, it is on the rear as you can see it just trying to lift off every now and again.

I put a new chain on my SLX chainset today and all was good until I put some really heavy pressure on the pedals (Whites initial climb) and then the chain got sucked up.

The sprockets didn’t look worn and I took the bike to the shop at Glyncorrwg. The mechanic there stated it was most likely worn sprockets and I needed to replace the front rings and the rear cassette. Turned out he was right.

Weird though, the old sprockets and cassette looked pretty good to me.

In the first post you said new cassette etc, and then later say its 7 months old – which one is it?

7 months was a reply to another question asking how old the original parts were. Keep up at the back 🙂