First up is the bottom bracket.

The axle and bearings on which the cranks spin.

Race Face ISIS BB £69.95 www.silverfish-uk.com

We’ve always found Race Face bottom brackets reliable, and it matches the chainset. We’ve gone for the new ISIS splined axle – rather than conventional square taper – as it increases stiffness and strength at a point where we’ve always been plagued with problems. This actual unit has been running on a singlespeed (albeit not used much) for the last six months and has so far held up fine, which was more than we can say for all the previous cranks and BB’s.

We have to say in retrospect we’d be tempted by the new titanium version. Not so much because of the 30g weight saving but more for the new double layer seals and best of all – grease guard injection!

First check the required bottom bracket shell width (68 or 73mm) and then the axle length you need (anywhere between 109 and 122mm, though 113mm is pretty standard these days).

Once you’ve got that sorted check the threads in the frame are smooth and clear from metal swarf and crud. Most bottom bracket cups now come ready-treated with Loctite or similar to hold it in place once fitted but we normally ease initial entry by greasing the first part of the threads.

Check you have the bottom bracket the right way round by looking for a small R or L indicator. Be very careful not to cross thread the bottom bracket / frame as it’s a pain to get re-threaded. If you need to check you’re screwing straight and true look from the far side to ensure that the axle is aligned dead centre of the shell and doesn’t oscillate as you screw it in. You’ll also need to get the correct tool for screwing in the bottom bracket, which makes this another job worth leaving to your local shop if you’re unsure.

Different brackets have different instructions but we normally screw in the main body most of the way first, before adding the support cup from the far side. Then screw in the main body till it lies flush with the edge of the frame. We actually had to leave ours slightly proud for reasons we’ll explain later. To lock the bottom bracket in place you then need to tighten the support cup firmly against the main body.

Normally the chainset slides on next, but oh no not on the STP. That big swooping bottom bracket moulding means a conventional front mech. clamp won’t fit. Instead its designed to use an ‘E type’ front changer that bolts into a boss on the frame, with a carbon fibre support plate that encircles the bottom bracket cup. Unfortunately for our non-Shimano project only the big ‘S’ make this sort of mech., and unfortunately for our wallet it only comes in an XTR version.

So bang goes a possible SRAM front mech. (which we’d have used on any other frame) and on slides the XTR unit (with the inevitable dab of copper slip anti-seize grease on the bolt and it’s receiver in the frame.

One good thing is that it bypasses all the conventional set up strife. For the record here’s what to do with a conventional front mech. Find right size clamp for your seat tube (no, not seat post) diameter, or use Deore which uses a series of spacers to fit anything. Clamp it lightly in place and then move it up and down the frame until it’s at a level where the outer plate just clears the outer ring by about 2mm. Then look from above and rotate the mech. parallel with the chainrings to minimise chain rub.

Once that’s set, bolt the clamp firmly.

Now it’s back to the chainset.

The chainrings and crankarms group.

Race Face ISIS Turbine £164.95 Rings £72.95

There are a lot of chainset options out there, but the only widely available ISIS splined (Shimano use a different Octalink spline pattern) chainsets are from Race Face and Truvativ. The Turbine is not as light as the Shimano Hollowtech units but it is stiff, gets a long lasting steel inner chainring and comes with a reassuring lifetime warranty. Yes, we did consider the very sexy carbon and aluminium Race Face Next LP chainset, but it only saves 50g for £115. If we need to lose weight that badly we’ll just take the inner chainring off this one.

For those wanting maximum Britishness run a Middleburn chainset on a square taper, Middelburn, Hope or Royce bottom bracket.

If the rings and cranks come separate like this unit, you’ll need to bolt them together. Think lots of grease on all screw threads and make sure the rings are correctly aligned with the chain peg or small marker tab in line with the crank arm. Check the rings are the right way round too. Any pins and ramps should be on the inside, while any lettering should be facing outwards.

Tighten each chainring bolt a few turns before moving onto the opposite one, as doing each bolt up in one go, or in a rotary progression can cause misalignment. If the bolts spin hold the back part with a broad screwdriver (or if you really have to get the proper Shimano tool for the job). Before you even start to fit the chainset we’d recommend using self extracting bolts, as not all bike shops have ISIS crank pullers for removing your chainset. These use a bolt to screw the crank onto the axle as usual, but they also have a collar that screws around the outside of the bolt so that when you unscrew the bolt it pushes the crankarm off. The bolts for the hollow bottom bracket are specific to splined units, but you can use the screw in collar off any old self-extracting set which saves the high price for Shimano or other replacement units.

Opinion is divided on this one. but we’d also advise lightly greasing the axle and crank splines to stop squeaking in use. One last point before you start installing these cranks is to make sure that the steel washer that sits between the bolt and the crank arm is in place or you risk destroying the crank by just winding the bolt through the soft aluminium. Not that we’d ever do that, ahem…..

Having checked all that, push fit the cranks onto the axle, grease the self extractor bolt and screw it in with your trusty big 8mm Allen key. Close fit tolerances that keep the crank in place means this can be hard work but just go slow and smooth and watch your knuckles on the chainring teeth. In terms of leverage we always find it works best to squeeze the Allen key and cranks together (think ten past three on a clock) rather than pushing down on opposite sides (quarter to three).

ISIS units screw right up to the axle stop, while Shimano and square taper units generally have some of the axle taper still showing, it should be obvious when the crank is ‘home’ though.

Our last piece of ‘sucking eggs’ advice is to always check the cranks on either side are in line before you tighten them up and make a proper fool of yourself ‘galloping’ down the trail.