Chain slipping baffling me

Saltwheeler

Hoping someone with more experience than me can kindly help with a possible explanation to the following chain slipping problem:

I bought a Kona full suss MTB three months ago with a Race Face narrow-wide 34 tooth chainring and SRAM 1150 XD 10-42t 11spd rear cassette. I've just changed the chainring from a 34 tooth to a 32 tooth, still Race Face narrow-wide.

Since swapping the chainring I've got chain slippage only when in the 42t ring on the rear cassette and applying pressure climbing hills.

I've shortened the KMC chain by two links and connected with a KMC quick link. The bike has done about 500 miles. The adjustment on the shifting seems spot on.

Anyone got any ideas as to what's causing the chain slipping please?

Many thanks

cooldad

Two full links? Or two parts of one full link? Sounds like a lot of shortening for 2 teeth. Best to measure the chain properly.

The Rookie

As you've changed the chainring wrap from circa 17t to circa 16t then if the chain was correct before it could now well be too short (which can be a real disaster!) as CD says, size it properly!

Slipping at the front or the back?

mugensi

The chain is too short, I had the same problem which completely baffled me as the chain and cassette had less than 1000kms on them. After trying indexing, re-aligning the derailleur bracket etc etc I left it into my LBS and asked them to sort it. They rang me 10 minutes later to say the chain was too short and as it was a Shimano chain they couldn't add a link and so fitted a new chain. The bike has been perfect ever since.

Saltwheeler

Thanks for the helpful replies. Yep, done all the usual alignment, indexing checks etc so the next thing is to double check chain length again when I can get to the bike in daylight (work gets in the way unfortunately)!

cycleclinic

but a short chain shoudn't slip. you still need to add links or better still replace the chain. I would also suggest using your LBS in future.

Steve-XcT

Could be a combination of chainline and KMC chain ....
I had a similar and frustrating issue ... moved back wheel from one bike (Hardtail with XT cranks) to another FS with SRAM cranks and fitted a 32T NW.....all on 1x10

Had the same problem.(only when under load).. stuck in an extra link, then 2 full links... as I had the KMC ... and it still did the same...

I've changed chains loads of times.... but this was frustrating.
I think the KMC chain comes off easier... the SRAM are apparently the most shaped.... and basically the chainline and going to much smaller ring is acting like a rear mech ....

I was half way through going to a 1x11 (had parts but work/freetime and also use of wheel on both bikes was a issue) so I switched over to M8000 and Shimano chain and the issue seems to have gone away....

Saltwheeler

Thanks for all of the constructive comments. I'm pretty convinced after further investigation that the chain length is not the issue: there's plenty of range of movement in the rear hanger, even with the air taken out of the rear shock.

Interestingly, all I've done is replace the 'same model' chain ring from a 34 to 32 tooth, and with plenty of chain length still available to take account of the movement of the rear shock so the logic of this one baffles me. I've ordered a new chain and will fit this to the same length I had when I was running the 34 tooth chain ring.

If this fails, I will no doubt have to take to the bike shop, but with the possibility of changing chain ring size many times over the coming years I'd like to get to the point of not spending out every time on something that should be a routine procedure. All of the local bike shops are booked up this time of year getting bikes ready to go out of the door before Christmas, but if the new chain doesn't work I'll definitely need to book it in!

Just to clarify from a previous comment, the chain's slipping over the 42 cog on the cassette. It's a 1 x 11 set up.

Frustrating, but keen to see if a new chain and the original chain length sorts it.

Saltwheeler

A quick update...

Have finally got round to installing the new chain, at the same length as it was on the 34 tooth chainring. Gotta say it looks too slack to me with the derailleur not putting much tension on the chain when in the highest gear.

However, changing the chain now results in it being impossible to change gear into the largest cog (42T) at the back! The chain won't go there even when dialling in more tension to the gear cable.

Will start from scratch setting up the gears tomorrow as have run out of daylight but me thinks it could be time for the LBS!!