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First Impressions – Fatback Sterling 4.25″ Fat-bike Tire

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The Fatback Sterling is a new tire for your fat-bike from long time fat-bike purveyor, Greg Matyas at Fatback Bikes and we’ve got our hands on a pair for testing.

Labeled as a 4.25” with a prominent Hot Patch for the Fatback Sterling name and the manufacturer, Vee Rubber, the tires, sporting a 120tpi casing, weighed in at 1236g and 1238g on our Park Digital Shop Scale. Greg’s website says 1300 +/-g so this is great. Well under the advertised weight and in the range of several of the more popular light-weight fat-bike tires out there.

A little dust from the shop floor makes the tread pattern stand out!

A little dust from the shop floor makes the tread pattern stand out!

The computer optimized tread is directional and has several different shaped knobs along with extensive siping of the knobs. The pattern has reminded some who’ve seen the Sterling in its prototype form as “Tetris-like”. Seem an apt description.

Make sure that if you want to run the Sterlings in the recommended direction of rotation you look at the sidewall for the direction arrow. There is a lot going on with the tread and it may not be readily apparent what direction to run just by looking at it. That said, I bet a few of you will run them reverse depending on conditions. I expect we’ll give that a go too. Meanwhile…

Greg mentioned to us that the Sterling is optimized for a 70mm rim so for the first rim/tire combo test I mounted up the Sterling on a 70mm Northpaw prototype rim that I’ve been using for some time and am pretty familiar with. A little Uncle Dick’s Bead Slip and the tires popped right into the bead.

The tires I removed from the Northpaw rims were 3.8” Ultra-Light version of the Surly Larry so I measured those up before I unmounted them so we could compare the size and weight of the Sterling with the UL Larrys.

So, how do they compare by the numbers? BTW, these measurements were done at 15psi. Lowering the pressure is doing to change the size nominally and the contact patch more so. Keep that in mind.

4.24” Fatback Sterling

  • 1236g
  • 98mm wide at the casing on a 70mm rim
  • 90mm at the edge of the outer knobs
  • Diameter 740mm

3.8” Ultra-Light Larry

  • 1139g
  • 92mm wide at the casing on a 70mm rim
  • 89.5mm at the edge of the outer knobs
  • Diameter 728mm

Just looking at those numbers the 4.24” Fatback Sterling appears to have a bit more volume. The casing is both wider and the overall diameter is larger. Note here that the tread depth is similar so the difference in diameter is mostly in the casing.

I also have a bike set up with Big Fat Larrys and 82mm Rolling Darryl Rims so let’s see what those look like:

4.8” Ultra-light Big Fat Larry on an 82mm rim

  • 1360g
  • 104mm wide at the casing on a 70mm rim
  • 102mm at the edge of the outer knobs
  • Diameter 743mm

From those numbers it look like the Sterling is very much a ‘tweener tire. The BFL would narrow slightly on a 70mm rim but not by much. So, it seems that the 4.25” designation, while not really the width, does fit the naming convention of other fat bike tires by being between the 3.8” and 4.8” sizes.

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Maybe a bit hard to tell form this photo but the Sterling fits in between the existing 3.8″ and 4.8″ tires.

On with the test!

I set the tire pressure, in the shop temp of 65 degrees, at 15psi in the rear and 12psi in the front for my first rides on the local trails in light snowy conditions. BTW, did you know that tire pressure drops by about 2% for every 10-degree drop in ambient temperature? It has been hovering around 25 degrees here lately so the 40 degree drop in temp means that my riding pressure should settle in at about 13.8psi in the rear and about 11psi in the front.

My initial impressions of the tire on the trails and on the road transitioning from the shop to the trail is that it feels good. There is none of the self-steer sensation that some other tires introduce and they seemed to roll pretty fast. Grip on the trails, on this day, was fantastic. The temps were hovering right around freezing but there was not much glare ice on the trail just come crusty snow.

Nice, snowy beach!

Nice, snowy beach!

For my second ride I hit the beach with some of the MKE locals. The beach conditions were really varied. When we left in the AM there was a lot of sheet ice, crusties, foot-high shelf ice on the waterline and hard sand. As the day warmed to just above 32 degrees, the conditions got a bit wetter and the sand softened some but through it all the Sterling impressed me with its grip. Even on the wet, sheet ice I had enough traction that if I didn’t make abrupt changes in direction it was possible to ride most anywhere. I like to keep sand on the tires so that it can add some grip on the ice transitions. I think the small siping in the tread helps lock in a bit of sand for these forays. Seemed like I had better traction than with the Larrys.

In the crusty ice on the beach shore the Sterlings also gave me confidence that they would grip. The sound of the tread gripping the crust made me think the tread was doing some work down there holding on.

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FWIW, I transitioned from the shop to the beach, which is about 3 miles, on the streets of MKE and had the tire pressure set like above. Approximately 14psi in the rear and 11psi in the front. I had planned to lower the pressure on the beach but ended up not getting to it and never felt like I wanted it lower. That said, next beach ride I will drop them down to feel what I feel.

There are a lot more rides planned but I wanted to get out some initial impressions. So there you go!

Also on the agenda is a tubeless set up but that will have to wait for another day.

Retail Price on the Fatback website: $135.00

Note that Fatback gave us these tires for testing and didn’t charge us. Fatback is also a site sponsor. Regardless, I will give you my honest impressions throughout the testing.

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4 Responses to First Impressions – Fatback Sterling 4.25″ Fat-bike Tire

  1. JordyB December 4, 2013 at 2:37 pm #

    Nice write up Sven, pretty much exactly what I have to say as well. They have been great on Anchorage’s snow pack to date!

  2. Nelson Muntz December 4, 2013 at 5:51 pm #

    But…but…some guy (who has a high post count) on MTBR said just the opposite.
    Who do I believe?

  3. Viv Jones December 5, 2013 at 11:12 am #

    It looks like an interesting tire option for us that cannot fit a 4.8″ in the framw. Wish they would have put stud holes in them though!.
    Do you happen to know what the measurements of the Dillingers were on the RLD rims ?, it’s difficult to see in the photo.
    Thanks !

  4. Kid Riemer December 6, 2013 at 6:45 pm #

    So I see a 6mm difference in width at the casing between the 3.8″ Larry and this tire. Less than a mm of difference at the knob. Why is it called a 4.25″?