http://www.bikecyclingreviews.com/planet-x.html
I’ve had a good look at the Planet X carbon frames and have spoken to a few people who own one (and Planet X wheels) and all are pleased with the price, weight and the overall handling of the bike.
The SL Pro carbon frame takes an integrated head set, has all the fittings you would expect and an aggressive geometry with a compact design. The rear end has straight seat and chain stays giving it a “normal” look which will also give stiffness. From the riders I have spoken to the frame gives comfort on long century rides as well as stiffness for tight, fast cornering in criterium style circuits. It has quite a “chunky” head area which is reminiscent of early Giant frames; they were very good with exceptional rigidity. Four different sizes and a possible four different colour choices, weighing in at a reasonable 1120 grams for the medium frame.
For the time trial or tri-athlon rider there is also the Stealth Pro Carbon with its aero profile. It is very popular I the Tri world as is not too expensive but has everything you need and also comes in a 650c wheel size. Obviously this frame is heavier than the Pro road, but still comparable to other more expensive carbon TT frames. Five sizes including the smaller wheel 650c version and four colours are available. With tri bars and spacers the frames can be adapted to anyone’s body shape and size, a very good frame to start Tri with and then up-grade the equipment later.
There are quite a few other lesser known frames and many of these are very good frames, but be careful that they have a guarantee and a returns policy before you part with your cash.