"15-17-19"
I am for that too! Make the large 18.5" at the absolute lowest and 19.5" at the highest. I ride a 06' RFX with 20" ST with 4" GD post and it is comfy on the steep climbs and general trail riding but a little tall for more aggro, slopy-style riding with <1" seat post left in the lowered position on the downs (would go lower, but need a 5" dropper post for that). I am 5'11" with long'ish inseam, 34" and always had 19" ST bikes that were a good compromise for up/down with good standover.
Oh, how about a full length head tube, like 5.5" in a large, so people can run the least amount of spacers while obtaining adequate bar height. And 135 x 10mm is fine too, since I can transfer my current wheelset to new RFX frame, that just may be the deal breaker for me. 27.2mm ST diameter would be good to keep my GD post without having to use shims as well. ISCG is nice, but I am yet to have to use a chain device on the 06' RFX with a solid AM/FR build ridden frequently on rough terrain and never lost a chain yet. Must be due to running good chain length or something?
And lastly, how about coil shock options for those who don't want air, nor can spend $600 on a Cane Creek DB?
Thanks DT,
JG