UK brand Genesis is known for the prevalance of steel bikes in its range, and its currently tinkering with an ultra-high-end steel frame built from Reynolds's flagship 953 tubing. 953's pretty amazing stuff - it's made from a category of steel known as martensitic stainless steel, and boasts some impressive mechanical properties. It has, for example, ultimate tensile strength about 40% higher than the already very strong 853 tubing, and twice the UTS of 3Al/2.5V titanium. It's not quite twice as dense as Ti, either, so that's an impressive strength-to-weight ratio. And it's a stiffer material, so you can use smaller diameter, thinner tubes. Then of course there's the whole stainless thing. 953 is highly corrosion resistant and doesn't need painting, which is always a good look.

953 is not, however, without its downsides. One of them is cost - it's not cheap stuff, and other fledgling 953 projects from other brands have been shelved on those grounds alone. Another is the currently limited availability of tube dimensions - 953 was conceived with road bikes in mind, so anyone wanting to make an MTB out of it either has to improvise or persuade Reynolds that there's a market for fatter pipes. Genesis is working on the latter, but had to resort to the former for the prototype - that front end uses two road bike down tubes, with a bunch of extra gussetting. At the back, the stays had to have some extra shaping to allow clearance for a proper tyre, which brings us neatly to 953's other little idiosyncracy - it's very hard.

That means that key framebuilding operations like cutting and mitring tubes or shaping stays become distinctly non-trivial. Look closely at the back end of the Genesis proto and you can see the evidence - the builders have had to crimp the inside of the chainstays to get clearance because they couldn't get enough of a bend in them, and the seatstays have ended up with tiny creases on the outsides of the bends because the hardness of the metal makes it difficult to put smooth curves in it.

Those kinds of things are exactly why prototypes are made, though. And really, this one is barely even a prototype - it's more of a mule, something put together to get an idea of what the tubing is capable of and, most importantly, how it rides. Genesis is confident that it can produce a frame of comparable weight and price to its existing titanium offering, while having a distinctly different feel. And while it looks like there's a long way to go - particularly given the freshly-introduced, and remarkably onerous, CEN tests that all production frames must pass - it reckons that it may have frames on the market this year.

More about Genesis (incuding details of frames and bikes that you can actually buy right now) at www.genesisbikes.co.uk.