Cassette compatibility and specs

Dellphinus said:

A couple questions:

I see cogs/cassettes specified as 12-23 and 12-23t. Is the t significant, and if so, how?

Are Shimano XT, XTR, Ultegra cassettes compatible/interchangable?

T is how many teeth are on the cogs. Yes, but with the big cog MTB deraiers, you will also need a RD with enough capacity to shift it.

boudreaux said:

T is how many teeth are on the cogs. Yes, but with the big cog MTB deraiers, you will also need a RD with enough capacity to shift it.

Thanks, wrt to the t, that's what I thought, but was confused by things such as this, from another thread here:
"Let's say you have a Record or Chorus 12-25 10v cassette now and want that exact gearing above - except the 28T would have to be 29T and in actual use there is very little difference - you'll have to take out the 16-17 combo, as well as the 19-21 and 23-25 combo's because on Record & Chorus those gears are pinned together. Buy the single 16, 18, 21, 23 cogs, and then the 26-29 combo. The 16, 21, 23T cogs are $12.88 ea. + $19.88 for 18T + $49.88 for 26-29T combo = $108.40, plus shipping and use your 12, 13, 14, 15 existing cogs/spacers."

The use of the T sometimes and not others was throwing me.

So I can use cogs form an Ultegra on my XTR; no worries about the HG/IG two teeth at once (if I understand it correctly) concept?

Thanks again.

Dellphinus said:

............... no worries about the HG/IG two teeth at once (if I understand it correctly) concept?

Thanks again.

I have no clue what you mean.

boudreaux said:

I have no clue what you mean.

Thought I read where the HG cogs were designed so the chain would engage teeth on two cogs simultaneously as you shifted. Cogs were designed to work with other HG cogs, and had to be oriented properly?

Did I misunderstand, or was it BS?

Dellphinus said:

Thought I read where the HG cogs were designed so the chain would engage teeth on two cogs simultaneously as you shifted. Cogs were designed to work with other HG cogs, and had to be oriented properly?

Did I misunderstand, or was it BS?

Yeah, there is a difference in ramping between IG and HG cogs. Shiamno says use IG chains with IG casettes.Sram chains work with both HG and IG casettes.