Floatation.

In certain circumstances, the floatation provided by a fat tyre bike (I’m talking about ~4″ wide tyres here) allows forward progress where a ‘normal’ bike tyre would come unstuck. This is as true for packed snow as for boggy, waterlogged ground.

In addition, I have found fat tyres ‘smear’ on densely rocky trails. I am thinking here of Highland passes such as the Lairig an Laoigh. The low pressure, flexible sidewalls and ability to deform around the low amplitude but high frequency (if you will) trail, again, allows forward progress.

As time has passed I have gone to wider, lighter rims and, with this most recent wheel build, I think I might have my mucky paws on the best there is, thanks to the recent release of the DT Swiss 350 197mm Big Ride hub (with thanks to lacemine29).

The rims are HED Big Deal rims, from Tim, at Sideways Cycles. They are 85mm wide, weigh a frankly astonishing ~450g and build really well. I would never have considered these rims previously: then I rode my friend’s fat bike.

Sean has Industry 9 hubs built to HEDs on his bike. Dropping 250g or so over an aluminium rim makes a noticeable and welcome difference and they feel solid.

I got the usual extremely good advice from Jon at Justridingalong for the spokes. I wanted something durable but on the lighter end of the spectrum. In this instance, Jon recommended D-lights from Sapim. These spokes have very short 2.0 sections with an unusual 1.65mm centre section. This makes them less prone to wind up commonly found when building with DT Revolutions or Sapim Lasers, which are 1.5mm in the middle. Of course, bladed spokes can be used with a holder to stop windup altogether, but the advantages of a bladed spoke are otherwise negligible on an mtb (though DT claim they are the most fatigue resistant spokes they make) and the cost is high.

I was impressed with the spokes.

Nipples are DT Swiss aluminium Pro Lock and I used Sapim round washers for the nipple at the rim (as recommended by HED) from DCR Wheels. A normal washer would be fine, though heavier and HED now have some washers with some sort of rubber or neoprene coating to aid tubeless set up.

Of course, building a single wall rim with aluminium nipples means getting the spoke length absolutely bang on as you need to fill the nipple at least to the bottom of the nipple slot, but I did not want to end up using a dremel on protruding spoke and risk damaging the rim. Advice here is measure, measure measure. I would highly recommend paying attention to published ERD but *always* measure it yourself. In this case, I found the ERD to be 566.5mm with 4.5mm left and right spoke hole offset. This means, with the DT Swiss Big Ride hub, I would need 279mm left and 277mm right for the rear wheel. I used freespoke for the calculations.

I converted my Centrimaster recently (to allow 300mm OLD hubs if needed!) with the fat hub kit and I used a new spoke key, from P&K Lie. This is compact, with a wide flat thumb paddle and a spot on interface for the spokes. I think it is very good, though quite light in the hand.

They built smoothly and easily, to a very balanced 85kgf on the ‘high’ side with less than 0.1mm of lateral and radial irregularity. The rear weighs around 900g. Sweet as.