BikeRadar's resident cross-country racer Joe Norledge has recently been putting his whippet frame to use testing two XC machines that deviate from the standard hardtail formula: BMC's Teamelite 01 XX1 and Trek's Procaliber 9.9 SL.
These are both seriously spendy bikes, and both use individual methods to build compliance into their frames.
This means both bikes are comfier than your average razor sharp hardtail, with the aim being to reduce fatigue. BMC has gone down a semi traditional 'softtail' route, with its elastomer sitting between the rear axle and top tube, taking away trail buzz whatever position you're in on the bike.
Metal rods covered by the elastomer prevent lateral flex. BMC says its idea came from the pros, who wanted more compliance. That's hardly surprising – with World Cup cross-country tracks getting gnarlier and shorter, many riders have abandoned hardtails in favour of full-sus machines.
Trek's IsoSpeed Decoupler, meanwhile, is a concept borrowed from its Domane road bike – here the 'elastomer' merely hides a pivot point and isolates the seat tube from the frame at the seat tube/top tube junction. (In other words, Trek most definitely don't describe this as a softtail – and have a point.) There's a little bit of fore-aft movement when you're seated, but it's feels stiffer than the BMC when riding – because it's essentially a hardtail when you get out of saddle.
Which is better for the privateer racer? Check the video out to discover our verdict – and look out for full reviews of both bikes…