News – Ibis Trans-Fat Fat Bike

by Brian Mullin on December 14, 2015

Ibis’s most versatile bike, the Tranny 29, just got a lot more versatile – Introducing the limited edition Trans-Fat.

The Trans-Fat utilizes the Tranny 29 front triangle, an all new rear triangle and a couple of clever bits to make it compatible with fat bike fitment standards. The Trans-Fat is available now in extremely limited quantities, and more will be in February. Orders can be placed with your Ibis retailer.


  • 3.25 lb Carbon monocoque frame
  • Designed to work with 120mm forks
  • Works with 4″ tires
  • Geared or Singlespeed compatible
  • Gates Carbon Belt Drive compatible
  • Internal routing for dropper posts
  • Clean, versatile multi-option internal cable routing
  • Tapered head tube (suitable for various Cane Creeks & Chris King InSet 3)
  • 100mm BSA thread bottom bracket (with provided BB92 adapters)
  • 177mm x 12mm Maxle rear axle
  • 160mm carbon fiber post mount rear brake mounts (we recommend 200mm/180mm rotors)
  • Headset: IS ZS44/28.6 | EC49/40
  • BB height w/ 4″ Jumbo Jim tires: 315mm
  • Geometry measured with 531mm axle to crown fork and our 3mm crown race

Grams Thoughts

I am happy to see Ibis stepping up to the plate and is releasing a fat bike, though a little late for the winter season. I like that they designed it around 4″ tires, keeping it between a plus sized and full on fatty, the latter that I find too ponderous to spin nicely on trails. I think their design will offer a lively and quick fat bike and it will be the ideal candidate for adventures in the snow and sand. They kept the chainstay short at 17.8 inches and decreased head and seat angle by 1º to 70º and 72º, respectively to keep things less fidgety.

The Trans-Fat is available three different options, a complete kit with XT 1X and a RockShox Bluto fork for $5099, a frameset for $1700 and a retrofit kit to convert an existing Tranny 29 to a fat bike for $699. I think the latter retrofit kit is pretty cool since it will allow owners of an existing Tranny the optional of creating a fat tire bike for a relatively decent price point. The complete kit includes a Shimano XT 1×11 drivetrain, Race Face Turbine Cinch cranks, RockShox Bluto 120 fork, KS LEV Integra dropper post, Sun Ringle Mulefut 80SL wheelset, and Jumbo Jim 26 x 4″ tires. The frames will come in Orange and Black and Medium, Large, and X-Large sizes.


The Trans-Fat uses a Tranny 29 front end and an all new swingarm with a couple of custom pieces that allow you to do the transition from 29er hardtail to fat bike.

The Trans-Fat falls into the category of a very sporty fat bike. We use 4” tires on the Trans-Fat, which are considerably lighter and livelier than the 5” tires found on many fat bikes. We want the Trans-Fat to be responsive and fun, whether on the sand, snow or dirt.

The 4” tires let us put a much shorter than typical chainstay on the Trans-Fat. We’ve slackened the head tube a bit from the Tranny 29, so the bike isn’t twitchy, which is a common complaint of fat bikes our test crew has ridden.

Trans-Fat Retrofit Kit

The Trans-Fat kit consists of:

  • An all-new swingarm that accepts 4” fat bike tires and a 177mm x 12mm Maxle through axle (SRAM standard)
  • 3mm thick crown race
  • BB adapters to fit 100mm BSA bottom bracket.

Note that you’ll also need a few other things to complete your conversions, like at RockShox 120mm Bluto fork, a set of 4″ fat bike wheels, a crank to fit on the 100mm BSA bottom bracket, and some warm clothing. Unless you’re riding it on the beach, in which case, you’ll need a speedo or bikini.

{ 0 comments… add one now }

Leave a Comment

Previous post:

Next post: