Reader’s Ride(s) – Mike’s UK Moonlander


Mike from the United Kingdom sent us this report about his Moonlander.

I’d like to share the story of my recent Moonlander build as I think that I might have some snippets of information which others might find useful and generally aren’t found anywhere else on the Internet and are not that obvious.

I’ve been MTB’ing for a many years and I have exclusively ridden ‘conventional’ 26” trail bikes. For a while I wanted a second lower-maintenance winter bike to add to the stable to keep me rolling in the event that my ‘main’ bike was down for maintenance/repair. On top of that I’d always wanted to build my own bike from scratch.

Having scouted all the options; 26ers, 29ers, hardtails, full-suss and every permutation thereof, and after sending myself a bit insane, a fat-bike seemed like as good an idea as any, and ‘I fancied a bit of a change’.

Most of my riding is done in Central England in the UK, so snow isn’t really a major issue for us, a few days a year at best. The going is more rain and mud and more rain, with the potential for some weekends away doing sandy coastal riding in the summer……probably in the rain!

I decided on a Surly Moonlander because I thought that 3.8” tyres a la Pugsley, Mukluk and others, would not be big enough – like I’d know – I reasoned to myself that if I was going to go fat, I may as well go for the fattest I could find. I doubt many here will any argument with that!

The Build Spec

Rather than buy frame, fork, rims, tyres, hubs etc. individually I decided on buying a complete bike with the intention of a complete tear-down and rebuild with a selection of new parts. It actually worked out cheaper in the long run, and now I have bike worth of spares!

The main spec change from stock would be to go for a full Shimano XT group-set including brakes – I’m a Shimano fan-boy and not ashamed to admit it! In doing so I would also go from the stock 2×9 to 2×10; a quick email to Surly confirmed that this would be possible with no chain-clearance issues and could still use the MWOD chain-rings.

Brake rotors would be up-sized from 160mm to 180mm, because I felt like it, and brakes swapped to hydraulic from the standard cable actuated. I understand the cold weather benefits of cable operated brakes, but here in the UK it doesn’t get cold enough for 99% of the year for this to be a factor. It’s generally wet and muddy most of the time and the low-maintenance benefits of hydraulic are more appropriate.

I’d also swap the ‘thumbie’ shifters for indexed rapid-fire shifters, again the cold weather isn’t that much of an issue that I’d need to be wearing mitts with any regularity. I’d also go for the direct-mount version to reduce on handlebar clutter.

The only other changes from the stock I wanted to make at this stage would be to swap the saddle for my preferred Fizik Gobi, and to try out some of those funny shaped Ergon grips.

I started with a full tear-down so I could treat the frame and fork internally with J.P. Weigle Framesaver corrosion inhibitor/preventer – 2 coats applied 24 hours apart. Then it was a case of re-building with my selected new parts. This is what I found out along the way:

2×10 Drivetrain

The 2×10 does work, but not without a good bit of tweaking. In other words, it’s not quite as simple as replacing parts – at least not with the parts I’d chosen!


Firstly the switch to a shadow-type rear derailleur means that you have to be careful how far back in the drop-outs you run the rear wheel. If you go too far, you run into clearance issues between the chain and the B-axle nut when shifting between the smallest two cogs. I found this out when the B-axle retaining circlip went missing, having been flicked it off by the chain during shifting.

Second, the horizontal drop-outs, while versatile, don’t really work very well with QR’s when the wheel is anything other than full-forward in the drop-out. The drive-side of the axle was prone to slipping forward. So I have since bought a pair of Surly Tug-Nuts to alleviate this issue and add a bit of bling! Having one each side would mean that I could set, forget and be assured of perfect rear wheel alignment every time I remove the wheel for a puncture repair or whatever.

The first issue with this arrangement was that the lower bottle opener prongs found on the Surly Tug Nut were fouling on the derailleur, so they had to be ground off flat. (It looks like this wouldn’t be a problem when used with a conventional non-shadow type derailleur).

Another problem is a standard 135mm long QR skewer isn’t long enough when using Surly’s Tug-Nuts and the supplied adaptor washers on both sides of the frame! To get around this I converted the standard XT rear hub to a longer solid axle normally found in a 145mm (tandem) rear hub and used track-nuts. (You could use a longer QR (or different tug-nuts) to solve this, but as it turns out I’m finding the solid axle solution workable. It’s not really any more inconvenient over QR; other than having to carry a 15mm spanner in my trail pack, and I’ve come to like the extra security of a bolted setup in horizontal drop-outs).


This is where I had the most problems. I ran into clearance issues between the outer derailleur shift plate and the crank-arm. To resolve this I had to use the supplied 1mm spacers on the MWOD chain-rings to bring them inboard as suggested in Surly’s setup instructions available to download from here: This didn’t affect chain-tyre clearance. However, I did find that the 150mm height from the BB centre to the centre of the direct-mounting hole to be too low as I was still getting crank-arm clearance issues. I found 160mm worked better.

In the end, shifting of the front derailleur still isn’t all that snappy, and setup of the limits and cable tension needs to very be precise, but it’s more than tolerable, particularly as I’m finding that I’m shifting less. Shifts from small to big chain-rings work better with the chain further down the small end of the cassette. (I’m wondering if Surly’s new OD crank-set with re-shaped arms might cure this altogether, and if this was one of the reasons for coming up with the new design in the first place:


I fitted a 36-11t rear cassette and this has given me an excellent crawling gear even with the standard 22-36t chainrings. I was half considering changing the front chainrings to the smaller 20-30t combo, but I haven’t yet run out of gears so I don’t think it’s going to be necessary.

This is my first time with a 2×10 chainset, and I have to say I’m not missing my 3×9, in fact I think it’s better. I’m making far fewer front shifts, and it doesn’t feel like I’ve lost any useable ratios. It’s basically a case of when the trails goes UP I use the small ring, and for anything DOWN I use the large one, and I can use the full range of the cassette on either chainring… simples!


I upsized the stock 160mm rotors to 180mm, and matched front and rear so I can swap between the two in case I somehow bend a rotor, but also because I’m a bit OCD about things like that – which is another reason why I have Tug Nuts on both sides!

At this point I also found that with the XT M785 calipers and 180mm rotors the wheels just about pass into the frame and forks, but you have to squeeze the tyre through and be careful not to scratch the rims on the calipers as you go. I think I would have struggled with the larger 200mm rotors.

I also found that the range of movement in the slotted holes for the rear caliper mount do not allow the wheel to sit full-forward in the drop-outs without the caliper binding on the rotor, so tug-nuts are fairly essential unless you like faffing around with wheel alignment every-time you fix a puncture.

Other Mods

The bolted non-QR Surly seat-clamp had to go and I swapped it for a Salsa QR – very nice, works a charm.

The Fizik Gobi saddle choice came with me from my other bike for no other reason than it fits my undercarriage.

The Ergon GP1 grips actually work well and are far more comfortable than conventional grips for most types of riding. I probably wouldn’t use them for thrashing around technical trail centres on my all-mountain full-susser, but they do add significantly to the comfort of the bike for the majority of riding.

The black rim strips were changed to white to add a bit of pop!

The result is a bike that although doesn’t look too drastically different from stock is quite a bit different in terms of it mechanics, and its raised a few interesting issues along the way which hopefully others will find useful or at least of interest when modding their own bikes. Granted much of what I’ve said will be specific to the Moonlander and the specific components I’ve used, but I’d imagine you might come across similar problems with other components and maybe other frames.

Thanks, Mike! We always like hearing about our reader’s experiences with they fat-bikes.

If you’d like to see you prized fat-bike build on the pages of, shoot a few pix and send us a story to –

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3 Responses to Reader’s Ride(s) – Mike’s UK Moonlander

  1. Mike Mahoney February 19, 2013 at 5:12 pm #

    Sexy Bike

  2. Michael Travers February 20, 2013 at 1:40 pm #

    Really insightful review with some useful information. You can only read so much information on the internet but to have someone do a strip down review and find out the little niggles for themselves is priceless.

  3. James holloway February 20, 2013 at 9:36 pm #

    Some great info there mate. I kinda of was in the same place as you. Wanted to try something new etc. I went from a 160mm enduro bike to a fatty. Now my enduro is up for sale. The moonlander does everything I ask it to do. (Even race it here in the local mtb championship )Have you thought about putting a drop seat on? That’s my next upgrade. Will let you know how it goes

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