I'd recently been having trouble with my chain stuttering, slipping off teeth, particularly on the middle chain-ring.

My local repair man said I needed a new chainring and chain, so I sent him the spec for the bike (Giant Escape 0). He fitted them both and said he was 'fairly sure' the issue was sorted.

I've only been able to test the bike today (some days after the repair-man left the back back) but I now have similar issues on all chainrings.

Before I re-engage with the repair-man, I need to know if his having fitted a Shimano chain, instead of the original KMC X10, could be causing the new issues.

10 gears in back? the shimano chain is of higher quality.

as long as it's for a 10 sp.cassette,the chain is not the issue... it is revealing other issues.

the cassette and the other two chain rings are worn.... the new chain is riding up on the worn teeth.

in the future, replace your chain more often.

how long you go between new chains will be dictated by how often you clean/lube your chain, and what kind of conditions you ride in.

Ideally, the mechanic should've ridden the bike in the small chainring and all the cogs in he back, dragging the rear brake and putting maximum torque into the bike to see if it would skip, and then testing in the other two chainrings in the biggest cog. In the case of your bike I probably would've recommended a new cassette and all new chainrings--depending on the price, its sometimes more economical to replace the crankset entirely.

In this case its almost certainly a worn cassette. The Shimano chain is an upgrade.

Thanks for your advice - I'm going to replace the cassette myself - it doesn't look too difficult.

My cassette (Shimano Deore HG62 11-34) isn't widely available. Do you know what I can replace it with to avoid any re-adjustment of the other elements in the drive?

here's one alternative...
SHIMANO CS-HG500 HYPERGLIDE 10 SPEED---11-34T MTB BICYCLE CASSETTE | eBay

SRAM and SunRace also have similar cassettes.

and if you went with an 11-32 cassette, there are literally dozens of choices, with all levels of quality... fit your budget to the quality level.... and yes, there IS a difference in quality of the metals, finish, and shifting as you step up a level or three!

changing to 11-32 will not require resizing your chain, btw...

here one for ya , Shimano Deore HG62 10 Speed Cassette 11-34 | eBay

Thanks to you all for your considerate, helpful thoughts.

You will need a chain whip, the freewheel tool, and an adjustable wrench. Assuming you have the wrench, you'll save money over paying a shop if you do this twice. It is not particularly difficult. While things will generally line up well, I would also always check the rear derailleur adjustment any time I replaced the cassette. If you replace the cassette and you still get skipping, you need to replace your other chainrings. For recent components, these often need to be pretty specifically matched to the make and model of your crankset. The tooling to change this is pretty simple--a chainring nut tool, and allen wrenches in most cases.

How do I ID the individual chainrings on my crankset (Shimano T551 26/36/48)?