Okay sat with my brother (64 ex building contractor and motorcyclist, me numpty) and niether of us can work out what rockshox fork he needs, so please help

the options are

RockShox Revelation RLT Ti Dual Position Air 150mm Fork
RockShox Revelation XX Dual Position Air 150mm Fork

and

RockShox SID XX Dual Air 120mm Fork

looking to go on his turner flux which currently has FOX 36 talas at 130mm and 100mm, so longer than recommende but likes the additional front travel, he weighs approx 14.5 stone and is a bit charge through things, so

what is dual air? Can the travel be adjusted?
what is the difference between the rev models?
Which is the better fork?
Are the sids the wet noodles of yesteryear? (saying that my partner has a set of red sids 100mm and they are fab!)
can any be locked out?
Axel to crown heights?
All advice recommendations welcome!

what is dual air? Can the travel be adjusted?

Dual Air forks have separate valves for setting the pressures in their positive and negative air chambers. Those SIDs can probably have their travel adjusted to 100mm but that’d be a workshop job, not something you could do on the trail.

what is the difference between the rev models?

The XX has a remote, hydraulically operated, lockout. This does mean though that you can’t adjust its compression damping except between “open” and “locked-out”. Otherwise I think they’re both fairly similar. Both have Black Box Motion Control damping and both have Dual Position travel adjustment.

It may be worth mentioning that the lower travel setting on Dual Position air forks is softer than the full travel setting, so is more intended for climbing rather than another general purpose travel setting.

Which is the better fork?

It depends on what you want! 🙂 I have just got a set of the Revelation RLT Ti Dual Position yadda yadda yaddas and they’re very nice. I imagine that the XXs would be too, though.

Are the sids the wet noodles of yesteryear? (saying that my partner has a set of red sids 100mm and they are fab!)

SIDs were re-invented a few years ago and are pretty good now. The 120mm travel ones have a 15mm Maxle option too, if you need more convincing.

can any be locked out?

All of those forks can be locked out. The XXs have remote lockout levers.

Axel to crown heights?

No idea, sorry.

EDIT – beaten to it but in combination I think you have the answers you need!

what is dual air? Can the travel be adjusted?

> Dual air is where the +ve and -ve spring chambers can be independently set to fine tune suspension action. Dual air needs U-turn to adjust travel. Dual position air is where both chambers are set up automatically at the same pressure but allows you to drop the travel 30mm at the twist of a dial. Do not confuse the 2 names as they are very different.

what is the difference between the rev models?

> The damper – basically XX is race damping so firmer, RLT Ti is top end trail damping and plusher but less efficient. Explained well on the SRAM site. XX is less tunable than the RLT Ti but comes with a remote lever.

Which is the better fork?

>Depends on what you are riding but both Revs sound too long for a flux.

Are the sids the wet noodles of yesteryear? (saying that my partner has a set of red sids 100mm and they are fab!)

> No. Stiff as for an XC fork esp. with the bolt through option.

can any be locked out?

> All of them as far as I am aware.

Axel to crown heights?

> Rev 150s ~529mm, Sid 120s ~500mm

All advice recommendations welcome!

100-120mm SIDs or Rebas probably the correct forks for the Flux but will doubtless feel a bit lighter and flexier than the 36s currently on.

Many thanks helps greatly

Thanks