A special thanks to Bill over at Fatbikes.com for this FAQ section.

Should I go with 80mm rims or 100mm rims?

Unless you have some epic trips planned, like competing in the Iditarod Invitational or a heavy-duty “bike-packing” trip, 80’s are your best bet.  Lower weight, lower rolling resistance, and a full drive train make 80’s the best all around option.  That said, if your adventures require maximum floatation, there is no substitute for increasing the size of your contact patch.  Understand that making “hundies” work requires that you remove a cog or two from the cassette to get the chain to clear the now massively wide tires.

How does the Surly frame offset work?

In order to get the chain to clear the wide tires, the seat stays and chain stays are bent to the drive train side of the bike by 17.5mm.  To bring the wheel back to the centerline of the frame, the rim has spokes holes closer to one sidewall.  The advantage of this design is it allows you the ability to use any standard mountain bike hub or internally geared hub.  The wheels build up very strong.

What is the ERD of the FlatTop rims?

FlatTop 80 = 540mm
FlatTop 100 = 547mm

What are the seat post sizes some for the snow bikes?

  1. 9:ZERO:7 Aluminum = 30.9mm
  2. 9:ZERO:7 Titanium = 31.6mm
  3. Carver O’Beast = 27.2mm x 400mm
  4. Surly Neck Romancer (Black Ops) = 27.2mm
  5. Surly Moonlander = 27.2mm
  6. Surly Pugsley = 27.2mm

What do you use to cover the holes in the drilled FlatTop rims?

We use Gorilla Tape or 2”1/5 inch nylon ribbon.  The ribbon is available at most fabric stores and comes in a variety of colors.

Where can I get an extra 9:ZERO:7 derailleur hanger?

The 9:ZERO:7 uses a design unique to the frame.  You can purchase extra hangers from Fatbikes.com for $27.00

What racks work best on your frames?

Given the many options for attaching a rack to our frames, most racks will work fine.  If you decide to use the rack mounts on the dropouts, understand you will need a rack designed for use with disc brakes. The very best option is to not use racks.  Instead, investigate the options offered by Eric Parsons at Revelate Designs.

What PSI works best?

That depends on the conditions.  Follow this maxim: When in doubt, let air out.  Soft conditions will require a PSI of around 5 (0.4 BAR).  This is low, so low, in fact, that you will see the sidewall of the tire bulge out when you hit a bump.  Don’t let the rim hit the ground though. If the trail is hard, you will see the best performance with a PSI of around 15 (1.0 BAR).

Should I go with a 100mm centered fork, or a 135mm fork?

For ease of use and maximum clearance, the use of a 135mm fork is recommended.  However, if you have a wheel set using a 100mm front hub, a 100mm fork works fine, but you will need to twist the wheel to fit the tire between the fork legs.  Use of 100mm wide rims requires the use of a 135mm fork.

Should I run clipless or platform pedals?

This is a debate that predates the invention of the super wide rims.  Strong arguments can be made for both options.  It is more difficult to keep your feet warm with a clipless setup; however, you gain a tremendous amount of pedaling efficiency, especially in hillier terrain.  Clipless systems can ice up, but platform pedals can seem sloppy, especially if you are used to riding clipless pedals on other bikes.   That said, we ride clipless pedals.

How do you keep your feet warm?

If you are using a platform pedal, choose a lightweight, insulated boot.  Based on our flat pedal riding experiences, the Steger Mukluk is the warmest option.   Size this boot up one or two sizes.
For clipless pedals, the best off-the-shelf option is the Lake MXZ-302 winter cycling boot.  Consider buying the ‘wide’ version.   Buy the boot two or three sizes bigger than your normal size.  Buy some insulated booties to fit over the boot, and wear gaiters.  In very cold conditions, wear a liner sock, then a vapor barrier liner sock, and then a thicker, medium weight, insulated sock.

Why do you only spec Gripshift shifters?

You will usually be wearing thicker gloves in cold temperatures.  This reduces the amount of finger dexterity and makes it more difficult to manipulate trigger shifters.  Gripshifters are just easier to use in cold weather.

Why do you spec such wide bars?

Riding on snow, especially in softer conditions, requires more steering corrections.  A wider bar helps brace the front end of the bike.  Also, riding in winter usually requires more accessories like pogies, lights, handlebar bags, etc.  The extra width allows for easy placement of accessories.  In fact, use of a carbon bar is recommended, since it has a warmer touch in cold temperatures than aluminum.

Which Surly tire works better? What does the difference in TPI mean?

The Endomorph is the original fat tire from Surly.  Tread patterns and which patter works best is usually a source of animated discussion.  The Endomorph works great as a front or rear tire.  Many people run the chevron treads backwards in the rear, forward in the front.  The Larry seems to feel about the same as a rear tire, but works better as a front tire in most conditions.  The directional knobs of the Larry help prevent the tire from “planing” through soft conditions.
There are two versions of these tires: 27 tpi or 120 tpi.  There is no standard for measuring ‘treads per inch’ in the cycling industry, so think of it as sleeping on stiff, course sheets, or soft, supple sheets.  They both work fine, but the higher tpi gives you a higher quality feel.  The 27 tpi tires are less expensive, slightly heavier, and have a stiffer feel to them.  The 120 tpi tires are more expensive, lighter, and yield a nicer, softer ride.  You would need to have both tires in front of you to actually feel the difference.

How well do the Surly tires handle on ice?

They don’t.  Be very careful riding over ice with these tires; they are optimized for riding on snow.  If you plan on commuting with your fat bike over icy streets and trails, consider building a 29-er wheel set and using studded tires.

How do I keep my water from freezing?

The best bet is to use a bladder under your jacket.  Keep the bite valve and hose under your clothing.  After drinking, blow the water back into the bladder to prevent the bite valve and hose from freezing.  If you forget, and the line freezes, it almost always freezes at the bite valve.  Suck on the bite valve and cross your fingers.  For shorter trips, putting the water bottle in your cage upside-down will work temporarily.

What are pogies?

They are one of the essential items for cold weather riding.  Basically an insulated cover for your handlebars, pogies will keep your hands warm in the coldest conditions, often while wearing only a lighter glove.  If you haven’t used them before, it is difficult to explain just how essential they are and how much of a difference they make.

A special thanks to Bill over at Fatbikes.com for this FAQ section, and for selling these beautiful aluminum frames.

2 Responses to FAQ

  1. Very good blog you have here but I was wondering if you knew of any discussion boards that cover the same topics
    discussed in this article? I’d really like to be a part of community where I can get opinions from other knowledgeable people that share the same interest. If you have any recommendations, please let me know. Thank you!

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