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Fatbikes are traditionally used for sand and snow which are surfaces which are loose and liable to break away under the weight of the bike and rider. They are also materials that don't generally stick to the tyre.

A muddy surface such as a peaty or poor-condition dirt track after rainstorms would also provide some likelihood that the material will break away under the tread. However, mud is often sticky and likely to stick to a tyre.

Therefore is mud more or less likely to stick to a fatbike wide with and diameter tyre than a small skinny ( < 2.5 inch ) mountain bike tyre where more pressure is being exerted over a small surface area, or more extreme a cyclocross tyre (these guys seem to ride and corner in muddy conditions successfully)?

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    Assuming the mud is of uniform consistency for several inches of depth, there is a maximum practical pounds per square inch (PSI) that one can place on the mud and not sink in (not too badly, at least). The wider the tire, the lower the PSI the tire exerts (for a given weight bike and rider) and hence the "muddier" the mud the tire can handle. Dec 3, 2014 at 12:50
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    Snow sticks. I rode to work on a fat bike with 4 inches of fresh snow and it still coming down this morning. I had a layer of snow on the tyre I was carrying and spinning the whole way. Dec 3, 2014 at 19:26

3 Answers 3

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Depends on how viscous and deep the mud is.

If the mud is viscous like clay and maybe leaves mixed and a fat tire can float and still get traction then the bigger tire is better.

But with normal mud and less than 6 inches deep then a thinner tire that will sink to the bottom for traction and might do better.

I was in a cyclocross race recently where we had a few inches of rain over the prior 2 days. There were both mountain bikes with 2+" tires and cyclocross with 33-35mm. The cyclocross were more effective. Even muddy grass the smaller tires did better. The bigger tires got pushed around and still did not get good surface traction.

The other factor is the amount of mud you are going to carry. A fat tire is going to hold a lot more mud and get heavy.

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  • yeah thats more like the answer I was after. Dec 3, 2014 at 14:52
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    You would be amazed at how much the mud can weigh. Sponsored riders will ever pit to get a fresh bike without mud and the crew will clean the bike the racer was riding.
    – paparazzo
    Dec 3, 2014 at 14:58
  • This answer misses the point of fat bikes - access-ability to trails which would be otherwise inaccessible (due to improved traction, flotation). Mar 13, 2016 at 17:38
  • @CraigHicks And your comment misses the point of of the question. The question is fat bikes in mud.
    – paparazzo
    Mar 13, 2016 at 18:46
  • @papa - Just talking about muddy patches on fire roads - my MTB can traverse more sections without walking than my cross - statistically speaking. It is simply due to the wide footprint and improved traction. Mar 18, 2016 at 18:29
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Fatbikes are traditionally used for sand and snow, but what about mud?

Yes.

Would a wide tyre with a mud-specific tread work better or worse than a narrow one in mud?

Better.

A larger footprint with lower pressure has better traction on surfaces with low shear strength.

I have an On-One Fatty which is a joy to ride on technical ascents (despite the weight penalty) and descents. The bike is not a limiting factor. The limit is me.

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    Your answer makes more sense - you are talking about much more muddy conditions than the selected answer is talking about. A fat bike can ride trails that a MTB or cross cannot. Its much more fun to ride a bike up a slippery slope at 3 kph than push it up a 1 kph while your feet keep slipping. Much more fun to ride slowly through a swamp of cow manure than spend 30 minutes wading through it pushing your bike. The selected answer misses the whole point - a fat bike lets you go places your otherwise couldn't (or shouldn't) Mar 13, 2016 at 17:30
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    Having been a fatbike owner for 2 years now, I think the surface where fatbikes gain most advantage and have greatest satisfaction potential is climbing loose dry rock and gravel. The "float" aspect doesn't come into play at all, but spreading your torque over a larger contact patch reduces the pressure at each contact point, reducing the risk of wheelspin. Still gotta think about weight distribution and line choice but it sure beats walking!
    – Emyr
    Mar 14, 2016 at 11:09
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Generally mud you want a skinny tire with very good clearing capability and depending on the mix of rocks and roots the hight of the knobs should be short. In situations where there is little rocks and roots, tall spikes work best.

I have raced downhill for several years on the east coast of the US which is notorious for being muddy races. We ran mud spikes but typically I had two pair of spikes, one with tall spikes and one cut with shorter spikes for more rocky conditions. Mud spikes also have a large fillet radius to the spikes to allow them to shed mud easily.

One factor that holds true for all situations with mud, the tire must clean well!

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  • That's the downhill side. What about the uphill side? Mar 24, 2016 at 1:59
  • Same same. Traction is traction.
    – Brady
    Mar 24, 2016 at 17:16
  • I can see that for any given width tire, tall spikes will get you through mud better than other tires of the same width, uphill or downhill. The disadvantages (weight, rolling resistance) don't impact so much on downhill, which is why they are called downhill tires. But if you just want to ride putting a priority on not being stopped by mud, then tall spikes are a good solution Mar 26, 2016 at 6:03
  • That's a little bit of a misconception. Weight and rolling resistance in DH racing is very important. It is a race! And not to mention there are several cross country tires that are modeled after a downhill tire because of how fast the DH tires can be - the Maxxis High Roller is the best example. The XC High Roller is a clone of the DH tire.
    – Brady
    Mar 26, 2016 at 10:02

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