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Big Fat Larry

This afternoon I picked up a new tire for my fatbike from Trails Edge: an ultralight version of the Surly Big Fat Larry (BFL). While this tire can have chain clearance issues on the rear of some bikes, it’s right at home up front in the Enabler Fork that comes stock on my 2012 Salsa Mukluk 2.

I’d never really cared for the Endomorph tire that came as the stock rear tire on the bike. While it was fine on sand and hard pack, on even marginally slick surfaces it’d unexpectedly jet sideways if even the slightest bit of power was applied, so I wanted to do away with it. As a possible solution to this I decided to try a BFL up front, and move the original Larry tire from the front of the bike to the rear, fitting it backwards for increased traction while pedaling. With this tire acquisition I was able to do so (photo).

One common trick on fatbikes is to put a very knobby rear tire on the bike to ensure that it doesn’t lose traction in the rear. This would be appealing for pure snow and trail riding but I frequently ride this bike on paved and hard pack surfaces, so I’m not sure this would be good for me. The super-grippy Nate would work well for this, but I can only imagine how quickly paved surfaces would wear on it, not to mention the tremendously increased rolling resistance. The Larry tread seems to be good for all around use, so I went with it.

When moving tires around to fit the BFL I was surprised to find that the original tires from the bike were both wire bead. At ~1370g the BFL isn’t a light tire, but the ultralight 120 TPI version with a folding bead ends up being a bit lighter than the narrower wire bead 120 TPI Larry’s ~1430g that had been on the front of the bike. The Endomorph which ended up getting removed from the bike is ~1420g, which makes the overall loss from the bike a whopping 50g, with 10g being transfered from the front to the rear. While it isn’t much (0.3% of the overall mass of the bike), I’m not going to complain about losing mass when going to a much larger tire.

Fitted to the Mukluk’s Rolling Darryl rims I measured the BFL at 4-3/16″ when inflated to 20 PSI just after installation. The BFLs are known to stretch quite a bit as they sit at higher pressures (in three hours it was up to 4-5/16″) so I’m not sure what the final size will be, but this is already quite a bit more than the original Larry’s 3-5/8″. It’ll be interesting to see how much it stretches overnight.

Here’s a few more photos of the bike and Big Fat Larry tire taken today:

· Surly Big Fat Larry tire, ultralight version (folding bead), as shipped from QBP.
· Surly Big Fat Larry on a Rolling Darryl rim at 20psi in a Salsa Enabler fork. There is plenty of room to spare.
· With the Big Fat Larry on the front of the Mukluk I moved the regular Larry to the rear, and reversed it hoping for greater traction in the snow.
· Current state of my Mukluk, with a Big Fat Larry front tire, reversed Larry in the rear, bash guard, trigger shifters, and lights. Weight is 35.38 pounds as shown.

Since I had the scale out I decided to weigh a few parts of the bike and see how it adds up. Here’s what I came up with:

Front Wheel w/ ultralight (folding bead) Big Fat Larry Tire: 7.62 pounds
Rear Wheel w/ wire bead 120 TPI Larry : 9.2 pounds
Tube: ~450g
Larry Tire (120 TPI, wire bead): ~1430g
Big Fat Larry Tire (120 TPI, folding bead): ~1370g
Endomorph Tire (120 TPI, wire bead): ~1420g
Complete bike as seen here with front and rear lights: 35.38 pounds

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