what was bought for

Didn't get round the hill at lunchtime so I went round once on the way home on normal bike then once again a bit later on the spare, finally getting a chance to compare them on the same terrain in roughly similar conditions to see which works best. It wasn't made particularly simple by the conditions being markedly more snowy on the second lap, nor by the wildly different braking characteristics, nor the fact that the lower gearing is available on the skinnier tyres, whereas I had to stop and push for a few yards on the spare despite the fatter tyres when the relatively high gearing for the slope, speed and available friction resulted in an inability to sufficiently achieve a balance between wheelspinning and maintaining forward motion.