First, I’d like to tell you a story. We began the ride on different wheelsets. Not because we wanted to, but because of a balls-up with the wheel order. I departed on what we’d originally planned for — Sun Rhyno Lite 36-hole rims, DT Swiss plain guage spokes, and Shimano Deore XT disc-compatible hubs. I’ve been riding on them since the beginning of the trip, almost without incident. Andy’s story, however, has been a different one, as you’ll know if you’ve been reading our blog.
There are many cycle tourers out there using Mavic XM721 rims, and as many horror stories as there are advocates. These rims are designed for downhill mountain-biking, so you would natually expect them to be made of tough stuff. No doubt they are, and no doubt they are designed to run big fat knobbly tyres at the relatively low pressures that the downhill biking crowd use in order to stick to the dirt with such style. They probably aren’t designed for narrower, high-pressure expedition tyres such as the ones that we (and countless other long distance cyclists) have been using.
That’s probably the reason that after just over 3 months, Andy’s rear rim developed a crack along one of the braking surfaces. It appeared one morning, and by the afternoon was 6 inches in length (6 real inches, mind you) and the inner-tube was emerging from the gaping hole. I’m as sure as I can be that the pressure of the tyre was the cause.
Our lesson has been painfully learnt, and we suggest you follow our advice (and that of numerous others) and don’t use this rim for touring except if you plan to carry no luggage and use 3‑inch downhill tyres. Much better would be the rims that I’ve been using (and that Andy has switched to). Recommended by numerous other cycle tourists for their strength and durability — and compatibility with the standard choice of Schwalbe XR expedition tyre — we had these hand-built for us. They are also compatible with rim-brakes.
Onto the wheels themselves. I have not yet serviced the front hub, but I had the bearings out of the rear hub twice in 6 months. These are standard 1/8‑inch ball bearings, which should be easy to find replacements for.
The first time, I was disappointed at how little grease was applied in the factory, and I would suggest repacking the bearings with a little more grease before you set off (this will also give you some hub-service practice if you aren’t accustomed to it).
The second time (after 4 months), I had neglected my maintenance and the rain and regular drivetrain cleaning had washed most of the grease away, which I admit was partly due to my overenthusiastic washing practices. The bearings had been running dry and needed to be replaced.
From now on, I will have the rear hub’s bearings out more regularly to keep them well greased and in good nick. There may well be better freehubs out there than Shimano, but none will have the same worldwide availability and compatibility throughout a wide range of parts.
A spare Shimano freehub and the tools to replace it should be part of your spares kit if you’re headed to really remote places. Luckily, as long as you can remove the cassette, removing the freehub itself is actually very simply, needing only a hex wrench and a good bit of elbow grease.
The wheels have rolled through everything in their path, carried the weight, and are still perfectly true. Have your wheels built by a reputable wheelbuilder — it’s an art. Like all moving parts, the hubs need attention — prevention is better than cure. But don’t use Mavic XM721 rims. For real downhill tyres and riding, great. For touring on 2.0’s or thinner — NO.
For the Sun Rhyno Lite rims on Shimano XT hubs we’re both now running, we think that regular hub servicing is a better long-term solution than sealed cartridge solutions that might last longer initially but conk out in a really inconvenient location, making you wish you’d gone with cup-and-cone bearings like these. The rims and DT Swiss plain-gauge spokes are bomb-proof, and the build quality by Leisure Lakes is top-notch. Now, we wouldn’t change a thing.