Slipping gears

[Jeorje]

Guys my bike since I put a new chain is slipping in top gear if I'm peddling hard.i have a shimano 12s..the gear is still perfectly fine.I thought it was maybe adjustment so if I screw in on the cable then it starts slipping in the next few gears also.screw out and gets other gears ok but still doesn't change my top gear ?any idea as I have a long ride planned for the morning? 

[BaGearA]

You can get the Bottom two cogs of shimano 12spd cassettes separately from your LBS 

[WaynejG]

I changed my cassette and chain end of last year. Felt as if the gears where randomly changing. Had it checked and adjusted but problem persisted. Then I started taking note. When the gears slipped and felt like a random change it actually stayed in the same gear. What felt like the gears slipping or changing it was the freebody that was worn.

[burger 555]

Is the chain not too long? Maybe the deraileur is maxing out before tensioning the chain

[RobertWhitehead]

That gear is worn 

[Jeorje]

The gear looks perfect though? I did shorten the chain but I didn't change anything

[Jbr]

2 hours ago, Jeorje said:

Guys my bike since I put a new chain is slipping in top gear if I'm peddling hard.i have a shimano 12s..the gear is still perfectly fine.I thought it was maybe adjustment so if I screw in on the cable then it starts slipping in the next few gears also.screw out and gets other gears ok but still doesn't change my top gear ?any idea as I have a long ride planned for the morning? 

If you put the old chain back on and it doesn’t slip it’s most likely time for a new cassette

[Jeorje]

Maybe it's the freehub when I put plenty watts?the cassette isn't even 4000km and mostly on tar and easy off road

[RobertWhitehead]

8 hours ago, Jeorje said:

Maybe it's the freehub when I put plenty watts?the cassette isn't even 4000km and mostly on tar and easy off road

How far along was the chain when you replaced it? If this is the gear in which you ride most of the time then it is possible for it to be worn. As mentioned by Jbr, put the old chain back and if it doesn't slip then ride it like that until more gears start to slip. If you put the old chain back and it does the same then you may (but very unlikely) have another issue. 

[Longbarn Killer]

A new chain slipping is almost always a sign that your cassette is worn too. 

[117]

Had the same issue, it's the small sprockets that are worn. Change the bottom two and it'll be fine again. 

My theory for the issue is the chain ring is too small. Ie, it allows you to climb in the small gears, which let's you put big power down on those small sprockets. If you run a bigger chain ring, then it'll force you to climb in a higher gear. Those 2 small sprockets are for top end, not standing on the pedals to rocket climb up a long hill (which is what I do/did and killed the two small sprockets in 1500km)

Good advice above to either go back to the old chain, or change the 2 gears

[Jeorje]

Thanks gents ...will try source 2 gears this am...can't use the old chain 

[droo]

18 hours ago, Jeorje said:

The gear looks perfect though? I did shorten the chain but I didn't change anything

You can't tell if a cog is worn by looking at it. If your chain was at 0.5% by the time you replaced it, the cog is done. 

 

Your other options are a slipping freehub or a bent hanger or RD, but these are less likely. 

[FirstV8]

I had a slipping gear and changed cassette ( 12000 km) and chain ( .75 ) . The slipping was still there in the smaller sprockets not the bigger upper range on my big chain ring ( X2 ) Checked the chain ring and it was as good as a serrated pizza cutter . The teeth had worn to sharp points and if you put the power down the chain would ride on top of the chain ring momentarily  . Changed the chain ring and the problem is solved . Look at the valley and the spacing between the teeth  in pic #2 

[Marcv]

On 2/25/2022 at 7:02 PM, BaGearA said:

You can get the Bottom two cogs of shimano 12spd cassettes separately from your LBS 

Can you please give me a couple names of LBS's that do this as we have ended up buying new 12s xt cassettes when only the bottom 2 are worn.

 

[BaGearA]

9 hours ago, Marcv said:

Can you please give me a couple names of LBS's that do this as we have ended up buying new 12s xt cassettes when only the bottom 2 are worn.

 

PM me