Mountain Bike Progress

The bike I’m building is coming along nicely. I would say it’s a bit more than half done:

Half-built MTB

As you can (hopefully) see above I built the wheels with two colours of spokes: the ‘pulling’ spokes are plain stainless-steel with nickel-plated brass nipples and the ‘pushing’ spokes are black with black brass nipples. At the hub single silver and black spokes alternate; at the rim you get alternating pairs. The concept was to connect, in the artistic sense as well as the physical, the silver hubs/rotors/cassette to the black rims/tyres. It wouldn’t have worked as well as it does if I had used the XT rotors as they have a larger black-painted central spider than the SLX rotors. I think it looks fairly cool, and even if it isn’t as noticeable as I had initially hoped it’s still distinctive.

The rims/tyres are a sealant-based tubeless system. It all works very nicely so far, and I can run far lower pressures (25psi front, 30 rear) than would be sensible with tubes. These pressures seem to give the right amount of tyre sag for good traction (roughly 15%) but you couldn’t go that low with tubes because the first hit would give you a snakebite pinch puncture. Hopefully this will all give me good traction.

The sealant I’m using is Effeto Caffe Latex; I can’t say if it’s better than anything else as I haven’t used anything else. But it certainly does the job: inflate those tyres on those rims with no sealant and they’re flat the next morning; add the sealant and swirl it around into all the nooks and crannies and they stay up no problem. I am considering adding this to my tubulars on the road bike if I can find a way to get it down the valve stem (they have removable valve cores).

To the extent that I have been able to test them without being able to ride the bike I am happy with the XT brakes. I can’t pull the levers to the bars and I have a good amount of lever travel between the engagement point and the furthest I can pull them, so I am reasonably hopeful that I will have at-least-adequate modulation.

The Race Face stem/bars/seat-post are excellent, as Race Face gear always is. I expect to tweak the setup once the bike is finished but it should be a good riding position from the off.

I have set the saddle-height to the same point above the centre of the bottom bracket as I have it on my road bike. This will not be exactly correct because the vertical height between the sole of my foot and the pedal axle is significantly less with a road shoe and SpeedPlay Zero system than it is with an off-road shoe and SPD system; but it will do as a starting point and I can gradually work upwards from there. I may not need to go very far because the crank arms I have ordered for the MTB are a little shorter than those I have on my road bike; I should therefore have added an extra 5mm to the acceptable vertical positioning window.

Checking the reach to the bars with a bit of string indicates it is slightly further than the tops on my road bike and much closer than the hoods or the drops, so again that should be good as a starting point.

Drivetrain should all arrive tomorrow and I’m hoping to be able to go for a test-ride on Tuesday.

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