'Marine Layer' - now retired.
'Black & Blue' - now retired.
photo by Steve Ellsworth
Our founder, Scot, doing some 'testing' up at Tahoe. Photo by Steve Ellsworth.
Jeff Kendall-Weed, doing some testing on vacation in Taiwan.
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Your Ibis Tranny 29

Total Price: $

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I love its ability to morph between belts, chains and gears while maintaining a solid feel throughout.

Jon Pratt, Dirt Rag Magazine
Ibis bike underline

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Tranny 29

Ibis bike underline

At Ibis we try to make bikes that are versatile, bikes that blur the lines between categories, bikes that create fun in a multitude of settings. That’s what it’s all about, right, having fun?

Bikes don’t get a lot more versatile (or fun) than the Tranny 29.

What is a Tranny?

First, it’s a lightweight, nimble 29er hard tail.
It also converts to a single speed with surprising ease.
And in single speed guise, you can run a smooth and quiet running Gates Carbon Belt Drive.
Finally, it’s easy to break apart for travel if you need to fit it into a confined space (like a suitcase or an apartment in New York City).

The Tranny is a playful bike. The stock setup comes with a 100mm travel front fork, giving the bike a super lively feel (yes, we said lively 29er). A 120mm fork option is available, which mimics the Ripley’s highly regarded front end geometry, only with a lower bottom bracket height and the confident handling that inspires.

Here are a few of the features, and check out the details tab for a lot more information.


  • 3.08 lb Carbon monocoque frame
  • Designed to work with 100mm suspension forks at 44mm rake
  • Also designed to work with 120 mm forks with 51mm rake
  • 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)
  • BB92
  • 142mm Maxle rear axle
  • 160mm carbon fiber post mount rear brake mounts
  • Headset: IS ZS44/28.6 | EC49/40
  • BB height w/ 2.25" tires: 302mm (11.9”)
  • Geometry measured with 500.8mm axle to crown fork

Reviews / Awards

This bike has been under development for several years. In fact the mold was cut at our current factory before the Ripley was. We retired the original 26” wheeled Tranny about a year ago, and with the Ripley done were finally able to focus on the Tranny. As with all of our bikes, they take a long time to make them how we want them. We think that our methodical and deliberate approach to product design shows in the details listed below.


One of the earliest parts of the development process is the industrial design of the bike, it’s “I.D.”.

We are one of the more fortunate bike companies on the planet, as one of our owners, Roxy Lo, also leads our design team. OK, it’s a design team of one. Still, we’re very lucky.

Here are a few of Roxy’s words about her design perspective on the Tranny 29.

“The Tranny's new lines and contours are svelte and angular. The design was developed at similar time as the Ripley, so the looks are very similar in all the tube contours; the Tranny 29 has an aggressive styling and an overall sleek nature. From the cable ports down to the derailleur mount, dropouts and fasteners, every detail is refined and minimized to be simple, functional and easy on the eye. From afar, you may not notice its subtle details, and that's fine. One can obsess over the nuances as time goes on.”

We think the gorgeous shot below embodies what Roxy is saying.

Roxy works in conjunction with our composites engineers to achieve a frame design that’s not only beautiful but incorporates many performance features. For example, look at the seat stays, they are purposely very thin in section. The tube shape gives you a much more comfortable ride.

A little lower, the carbon layup found in the chainstays is very complicated. You need the chainstays to be stiff but they also need to flex in the front so you can tighten the slot machine.  It's something you can only do with carbon because of it's anisotropic qualities. That is, it has the ability to be stiff in one direction and flexible in another. When we first proposed this to the engineers at the factory where we make the frame, they said “no one has ever done this before”. And as we all know, there’s always a first time.

Slot Machine

"Riding a singlespeed hardtail is so much more fun than a geared HT. It's like getting spanked by a dominatrix instead of your mom." – Tom Morgan, Ibis President

The slot machine (pictured above) is the sliding box section behind the bottom bracket that allows us to convert this bike to a single speed. By changing the length of the chainstay, you can tension the chain (or belt) without cumbersome adjustable dropouts or heavier eccentric bottom bracket.

Take a close peek at the section behind the bottom bracket. There's some hidden equipment down there we call the "Slot Machine". It's not really a machine, but it does have a slot that makes it adjustable. That allows us to lengthen the chainstays, so you can tension the chain (or belt), converting the Tranny into a bona fide single speed. Single speeds don’t have a derailleur, which is normally how a chain is tensioned. The slot machine takes care of that tensioning in a simple yet effective way. It's lighter than an eccentric bottom bracket, cleaner than a chain tensioner, and unlike sliding dropouts, can be adjusted with one bolt.

As an added bonus, that same box of magic along with the gorgeous bit of teardrop hardware at the top of the seatstays allows you to take the whole rear end off of the bike. Two bolts and it's in two pieces. Why would you want to do that? That makes the bike easier to travel with, and if you’re really nice to the people at the ticket counter, it just might be possible to fly with this bike, er, luggage, and not pay the exorbitant fees the airlines like to charge us to carry our recreational necessities. We’re not saying that you can always get away with this, but we’ve done it in the past and we’ll certainly try it again.

One other thing, the slot machine now has a nice little molded dust seal to keep dirt out.

Cable Ports

Another example of elegant simplicity and versatility is shown in the cable ports. There are many possible ways to route your cables on the Tranny 29.

For dropper posts, there's internal routing that can be fed through the top tube if you’re not using a front derailleur, or through the down tube if you are. The front derailleur housing can be setup with either full housing or interrupted, minimizing the rattle potential.  The rear derailleur is routed with full housing through frame. It’s very easy to route because the slot machine opens up, allowing you to route it both over the bottom bracket and back into the chain stays.

Additionally, all the ports come off leaving a larger hole to aid in routing.

There are three different ports to choose from. You can use the thru hole routing for full housing or one with an integrated cable stop for bare cable. We also have blank ports if you’re not running any cables. The internal post and rear derailleur have to be run with full housing, the TT can be interrupted.     


The Tranny has clearance for most tires up to the 2.3 range. There might be exceptions to that number, as manufacturers don’t seem to share the same set of measuring tools. A 2.25 Nobby Nic is fine (works great with our 941 rims), the 2.3 Butcher is fine, and a 2.4 Ardent is bit too close for comfort.


The Tranny 29 uses similar molding technology to the Ripley. We start by molding a sacrificial mandrel in exactly the shape that we want the inside of the frame to be. That becomes the 3D template for the bladder that holds all the carbon preform before it's laid into the mold. This allows the lay-up to be done in one piece, with no joints anywhere. The result is a more precise lay-up that doesn’t have to shift around to fill out the complex shapes. What that means for you is a lighter and stronger frame, critical factors in hitting our targets for weight and stiffness.


We like the tapered headset found on the Ripley, the Mojo HDR and Mojo SL-R, so we're using it on the Tranny 29 as well. It helps build a bike that is light and very stiff. The 1.5" lower portion of the steerer provides an exceptionally rigid front-end platform. Combined with the through-axle fork, you'll be amazed at the precision steering feedback you get, particularly when pushing hard.

You may use several different Cane Creek headsets or the Chris King InSet 3 headset.


We've made a provision on the Tranny 29 for 2 large water bottles inside the triangle.


If you want to run a 1X system, you’re in luck. If you want to run a 2X system,  you’re in luck. We are offering X01, XX1 and XTR 1X in the 1X guise, and the new XTR 2X, good old XT and also our Special Blend 2X if that’s the way you want to go.

142 X 12MM MAXLE

The 142mm Maxle rear through axle provides gobs of extra rear wheel stiffness in an extremely lightweight package, and compatibility across most wheelsets.


The bottom bracket is the new press fit integrated style called the BB92, also known as PressGXP. Once again, it provides you with a lighter, stiffer bike, and is compatible with most popular cranksets.


We’ve owned, ridden and tested a lot of 29ers over the last few years. Some of them we liked, some of them we really disliked. We found that geometry was all over the map with the different bikes and that none of them delivered the snappy handling we all love with our good old 26” bikes. So we set out to make our 29ers fun to ride, as similar to our current bikes as we could, with the added benefits of the fast rolling 29” wheels.

The newer shorter taper forks allowed us to keep the headtubes short, lowering the often too-high position of the bars. We even developed two sets of extremely strong carbon bars for the Tranny and the Ripley, a flat bar with a very generous 740mm width and a slight riser bar at the same width. They’re called Hi-Fi and Low-Fi. As in Fi-Bar. Or Carbon Fi-Bar if you please.

Before we finalized our geometry, we did a lot of testing of prototype 29ers with different head angles and rakes.

We settled on 70º with a 120mm travel fork, and 71º with a 100mm fork. Both give identical trail measurements of 80mm. It is important that a 51mm offset fork be used on the Tranny with a 120 fork, and 44 used on the 100mm setups, in order to get the best performance.

Trail measurement for the SL and SLR, Ripley and Tranny: 80mm


Trail might be a bit of an unknown measurement to some, as we in the bike industry haven’t been focused on it lately. In reality, it’s the most important dimension affecting handling of the bike. That’s right, it’s more important than head angle.

Trail is the distance between the contact patch of the tire and the imaginary point where the steering axis intersects the ground.

Someday, we will write a white paper on trail. We keep putting it off because we don't think anyone will read it.

However, it’s a very important subject and it’s what makes a bike handle good or handle poorly.

Show/Hide the Geometry Overlay

With 100mm fork (500.8mm axle to crown, 44mm offset)

Nominal Size   Small Medium Large X-Large
Seattube A 14.5” (368mm) 17” (432mm) 19” (483mm) 21” (533mm)
Toptube B 22.2” (564mm) 23” (584mm) 23.8” (605mm) 24.6” (625mm)
Headtube C 3.1” (78mm) 3.7” (94mm) 3.9” (100mm) 4.5” (115mm)
Chainstay D 17.1” (435mm) 17.1” (435mm) 17.1” (435mm) 17.1” (435mm)
Seat Angle E 73° 73° 73° 73°
Head Angle F 71° 71° 71° 71°
Wheelbase G 41.1" (1045mm) 41.9" (1066mm) 42.8" (1087mm) 43.6" (1107mm)
Standover Height (mid toptube) 26.8" (680mm) 29.5" (750mm) 29.5" (750mm) 30.5" (775mm)
Stack 607mm 622mm 628.5mm 642mm
Reach 378mm 393mm 411mm 437mm
Trail 80mm 80mm 80mm 80mm
BB Height (2.1" tires) 12” (305mm) 12” (305mm) 12” (305mm) 12” (305mm)
Sizing Guide (height-inches) 5'0" - 5' 5" 5'4" - 5' 9" 5'9" - 6'2" 6' - 6'6"
Sizing Guide (height-cm) 152 - 165 163 - 175 175 - 188 183 - 198

With 120mm fork (520.8mm axle to crown, 51mm offset)

Nominal Size   Small Medium Large X-Large
Seattube A 14.5” (368mm) 17” (432mm) 19” (483mm) 21” (533mm)
Toptube B 22.4" (569mm) 23.2" (589mm) 24" (610mm) 24.8" (626mm)
Headtube C 3.1” (78mm) 3.7” (94mm) 3.9” (100mm) 4.5” (115mm)
Chainstay D 17.1” (435mm) 17.1” (435mm) 17.1” (435mm) 17.1” (435mm)
Seat Angle E 72° 72º 72º 72º
Head Angle F 70° 70° 70° 70
Wheelbase G 41.5" (1055mm) 42.4" (1076mm) 43.1mm (1096mm) 44" (1117mm)
Standover Height (mid toptube) 27.2" (690mm) 29.9" (760mm) 29.9" (760mm) 30.9" (785mm)
Stack 617mm 632mm 638mm 652mm
Reach 363mm 378mm 396mm 422mm
Trail 80mm 80mm 80mm 80mm
BB Height (2.3" tires) 12.3" (312mm) 12.3" (312mm) 12.3" (312mm) 12.3" (312mm)


  • Seat Post Diameter 31.6mm
  • Front Derailleur High Direct Mount
  • Headset Mixed Tapered (1.5" EC49 lower, 1.125" ZS44 upper)
  • Bottom Bracket BB92/Press GXP
  • Rear Brake Post Mount
  • Rear Axle 142 Maxle

Sorry, no build kit info for the Tranny 29.