the mech is too far from the sprockets in the middle of the block.

That would be my thought too – chains can actually “bend” quite a lot side to side (by design obviously) so if the top jockey is too far from the cassette then it’ll never shift well. One possibility to help, if you’re using a Shimano mech is to replace the top jockey with a non-floating one.

emailed the distributors about that trickstuff cassette:

At the moment there is no pricing available although we expect to have this within the next week.
There have been 100 produced so far and they will start to ship in the next 3-4 weeks. I would expect it to be around £80-£90.

That sounds very cheap given that the middle section of the cassette is titanium… hope it’s correct though.

One possibility to help, if you’re using a Shimano mech is to replace the top jockey with a non-floating one.

Do the 10spd Shimano top jockeys still have float? I don’t remember noticing any. Either way, SRAM doesn’t do any better.

Mine doesnt do this. Am I just lucky or is it because mine is the 40t version thus when the b tension screw is set its not quite as far away from the other sprockets as it would be if I were running the 42t version?

That sounds very cheap given that the middle section of the cassette is titanium… hope it’s correct though.

How do you know that? Why would they make the most used sprockets out of ti?

Edit: because the largest ones are alu, makes more sense, although not all that durable.

I’m convinced that it’s simply due to the B-tension setting required to keep the jockey wheel off the big sprocket, the mech is too far from the sprockets in the middle of the block.

This is the answer. I’ve just been out and tried slackening the b-tension right off then shifting from the original cassette on to the General Lee. Worked faultlessly on these two gears but the b-tension is obviously then too slack to stop the top jockey wheel fouling on the top two gears. I’m running a GS mech, my dad has a SGS on his Superfly so I might try that and see if it shows any improvement

Is it me or are there only 9 cogs on that Trickstuff cassette?

I’m running a GS mech, my dad has a SGS on his Superfly so I might try that and see if it shows any improvement

I tried the same thing with my wife’s SGS mech. Much the same.

Tried the SGS mech…exactly the same issue like Robinlaidlaw above, oh well looks like I’ll have to just persevere

Is it me or are there only 9 cogs on that Trickstuff cassette?

I was thinking that…
There’s definitely 10 in this image though: