I build bikes based on the following framesets:

All ‘Kinesis UK’ frames are designed and rider tested in the UK - none of their frames are simply bought ‘off the shelf’. They believe that designing their frames to suit the unique riding conditions and styles of the UK is of utmost importance.

The Crosslight range, Racelight T and Tk and Maxlight frames are good examples of this philosophy. Because the frames are designed at Kinesis UK, they listen to team and rider feedback and respond quickly with tweaks, modifications or entirely new models.

The frames are very light compared to the big brands - the KR810 (rsp £999) weighs 1kg.

www.kinesisbikes.co.uk

http://www.teamkinesisuk.com/

Cotic are a small company based on the edge of the Peak District, producing their own frames to their own spec.

They are now one of the leading lights on the homegrown British microbrand scene, sprung from the success of their original long forked steel XC/trail bike, the Soul. 

I love their take on something fast - The Roadrat. Built for anything except the trails, this is the ultimate versatile machine. Have a look at the pics and example build pages.

Massi are a Spanish company with a large range of products.  I also work with

Salsa (www.salsacycles.com)

Surly (www.surlybikes.com) and

Singular (www.singularcycles.com)