I think I'd try phoning them.

Hi guys. Expecting delivery of my 631 Sirius on Tuesday but need a couple of q's answering and I can't see the info on their site.

What size BB & axel does it take? Looking at either LX or XT HTII. Also, what size seatpost? I've got a feeling it's 27.2mm but I cannot confirm this.

Cheers lads and ladettes. 

If you're looking at LX or XT HTII then you don't need to know the BB dimensions because it doesn't make any difference

Post is 27.2.

Well I've had around 10 emails from Stuart in as many days. Don't forget there's only 2 of them!

re: BB.... so 73x113 is fine?

Be carefull with the BB if you plan to ride with big tyres.

Mine is fitted with HTII and for 12mths i battled with having my front mech adjusted correctly without hitting my 2.35 tyres.  You are supposed to have one spacer on the drive side and none on the left.  I run mine now with 2 spacers on the drive side as this gives 2-3mm extra clearance.

This isnt an issue with 2.1 tyres.

I'm aiming at this being more extreme XT than hardcore hardtail. 2.1 on the back for sure, maybe bigger on the front.

Are you using a top pull front mech? I'm sure the website says you can use up to a 2.5" tyre so I'm wondering why you have probs with a 2.35 tyre!?!?

Which is why I was puzzled by Mike's thread saying you don't need to know the BB dimensions. surely you need to know the correct BB axel width for a triple chainset!

So, assuming I'm not going to stick 2.5 inch tyres on.... a 113 bb axel should do the job?! 

what mike was saying was that you dont need to worry bout bb axle length if you are using ht2 bb but if you are using isis/octalink/sq taper bb then the shell size will be determinded by the frame (yes 73 is right) and the length will be determinded by your choice of cranks

i run 2.25 nobby nics and the clearance is ok, just.

As 4AM said above, the front mech will need to be set up for your choice of cranks so tyre clearance will be different for each crank set up. the frame has room for 2.5 but what you can fit will depend on different factors (cranks/bb/mech etc)

hope that helps

PS, they are great frames.

I don't mean this to sound harsh in any way, but why do people keep mentioning setting up the front mech correctly. Surely setting it up so that each gear works without rubbing, is kind of obvious when building a new bike? It's like saying "tyres work better with air in". Kind of a given, really! 

Which is why I was puzzled by Mike's thread saying you don't need to know the BB dimensions. surely you need to know the correct BB axel width for a triple chainset!

Not with XT or LX HTII, because all the axles are the same width and they fit either size of BB shell. Just follow the instructions to get the spacers in the right place.

John, the design of the frame (And i am pretty sure i heard the on one scandal has the same problem) means there is very little room between the rear tyre and the seat tube.  This also brings the rear tyre close to the front mech in granny gear.  If i use one spacer as i am supposed to, it doesnt matter how i adjust the mech, it catches, or its a compromise on shifting quality.  It gets worse in the mud.