Andrew Whiteford 650b first impressions
Digital Hippy goes 650b
Converting between 26 and 650b
An HDR in Poland
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Your Ibis Mojo HDR 650b

Total Price: $

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Ibis knows how to wring a hell of a lot of performance out of their suspension no matter how long or short that travel is.

Vernon Felton, Bike Magazine
Ibis bike underline

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Mojo HDR 650b

Ibis bike underline

The Mojo HDR 650b is the fraternal twin brother of the Mojo HDR and the younger brother of the Mojo HD, taking the HDs technology and versatility a few steps further. As you can tell by the name, the HDR 650b features that third wheel size that all the kids are talking about these days: 650b / 27.5".

Highlights are below. If you want to hear the story of how this bike came about, head over to the story tab. The details tab will give you a lot of technical info about the bike. 

Maybe the best place to start would be the galleries tab, where we've got a few videos showing the bike in action along with some lovely big studio shots. 


  • 650b (27.5") Wheels
  • dw-link Suspension
  • 130mm of rear wheel travel
  • Shock specs: Fox Float CTD Adjust Factory Series with Kashima Coat, 7.875" x 2.0"
  • ISCG 05 compatible
  • Weight for the frame and shock, size medium, matte finish: 6 lbs
  • 67.1 degree head angle with a 140mm fork
  • Optional polycarbonate down tube cable guard
  • Chain stay length: 17.125"
  • 12 x 142mm Maxle rear axle
  • 160mm post mount left dropout, carbon fiber
  • Tapered Head Tube and Steerer
  • Compatible with Chris King InSet 3 headsets
  • Up to 2.35" rear tire depending on brand and height of cornering knobs
  • Dual row angular contact bearings in the front of the lower link that have less play than standard sealed bearings. Preload adjustment is not necessary. Large 28mm x 15mm x 7mm radial bearings in the rear for stiffness and long wear
  • The Bottom Bracket height is 13.5"
  • Front derailleur (if you use one) and adjustable seatpost housing (if you use one) run along the top tube
  • Direct mount front derailleur

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The Frame

The HDR frame is slightly lighter than the HD, around .3 -.4 lb (depending on size and color), yet is stronger and of equal stiffness. We've employed a new, more precise molding technique similar to that used in the Mojo SL-R to get the weight down.

One of the biggest and perhaps least visible changes comes from the completely redesigned swingarm. It has been retooled to give generous clearance for 650b tires, and also has cutouts for the new 11 speed drivetrains. And while the clearance number goes up, bb height goes down to a berm-hugging 13.5"

By shifting around our linkage locations and completely redesigning the swingarm, we've managed to add ISCG 05 chainguide mounting functionality and dramatically increased the front derailleur compatibility across both the 2X and 3X spectrum. We've also increased clearance for the new 11 speed cogsets.

With some other tweaks to the frame, we've made the frame compatible with Fox's new lighter weight LV air cans on the CTD shocks. 


The HDR is an extremely versatile bike. It can be setup a number of different ways, for a number of different types of riding. You can easily change front or rear travel and change wheel size to dial in the right ride for you.

Note that the HDR and the HDR 650b share the same frame. We change the stroke and length of the shock, along with its location on the frame, to give two very different setups with unique ride characteristics.

Our stock 650b setup has 130mm travel. By swapping out the "limbo chips" and changing the shock, you can easily change the bike to a 160mm travel bike for 26" wheels. That version is called the HDR and you can see it here

Here is a picture of the limbo chips:


The HDR features a mixed tapered headset with a 1.5″ lower and a 1.125″ upper. The 1.5″ lower provides an exceptionally rigid front end platform. Combined with the through axle fork and our very stiff front end layup, you’ll be amazed at the precision found in the front end, particularly when pushing hard. The HD is also compatible with the King InSet 3 headset.


With the popularity of the 11 speed cogsets on the rise, we've increased the clearance at the drive side dropout to allow for most hub/cassette combinations. We like the 11 speed drivetrains when utilized with a  32 or 34 cog, they nicely match the suspension kinematics that way.


We've managed to tweak things a bit in the linkage area of the bike to make room for ISCG mounts. There's a removable plate if you don't need a chainguide or bash protection. 


We've found that some newer shocks are being built with air chambers that require a little more clearance, and we've provided that with the HDR.


Depending on brand and depth of knobs, most 650b tires up to 2.35″ will fit the Mojo HDR. We've found that different tire manufacturers seem to use different calibrations on their rulers, so it could be that there are some 2.35" tires that don't fit. 

You can fit up to a 200mm diameter rear rotor.


Cable routing is provided for cable actuated adjustable seatposts. Cable guides are all removable so you can have the cleanest possible look depending on your cable orientation and whether or not you’re running a front derailleur.


If you are an extremely aggressive rider, we’ve found that it’s possible to damage the brake line and derailleur housing that will be routed under the down tube. To prevent that from happening, we have available an optional polycarbonate cable guard that bolts on under the down tube.


We expect the HDR to get an extra heaping helping of abuse, so we’ve beefed up the lower link considerably, compared to the SL-R. It features dual row angular contact bearings in the front of the lower link that have less play than standard sealed bearings. The large 28mm x 15mm x 7mm radial bearings in the rear offer greater stiffness and longer wear.

The HDR 650b Story

The Mojo HDR has been jiggling around in our heads for the last 18 months or so. With the success of the Mojo SL-R, we wanted to incorporate some improvements in molding technology that we've been utilizing on the SL-R (lighter stronger stiffer). We also wanted to improve clearances for current componentry (front derailleurs, rear shocks and 11 speeds), and we've been scratching our heads on ways to add ISCG tabs.  

About the same time, we noticed there was a lot of enthusiasm for 650b wheels from our customers, with many of them running 650b on the Mojo HD. That wasn't a passing phenomenon either, the forums are positively lit up with 650b banter. We tried it first about a year ago on a converted HD 140. Everybody at Ibis liked it, so we studied our options. We all felt the BB was too high, and mud clearance was pretty close to non existant. We knew we were close to having a great new bike. We put all the dimensions into the cad model and we knew right away we could get there with minimal changes to the proven HD platform. 

Then we set out on the path to make the HDR, with proper clearance and BB height, along with the changes mentioned above (molding, clearances, etc).

The other part of the story is that the HDR in 160mm mode maintains geometry identical to the good old HD, which has been our most popular selling bike over the last couple of years.

That's how the HDR came to be. 


Bike designers know that bikes with lower bottom brackets ride better, due to the lower center of gravity. One thing that we've figured out recently is that the 5" change in center of gravity allowed by dropper posts makes a .5"-.8" change in BB height much less significant.

We think that's why adapting 650 wheels into bikes designed for 26" wheels are so popular, despite the raise in bottom bracket height. Five years ago, before everyone had a dropper, we think the popularity would not have been there, as the bikes would have been too tall.

What to call this wheel size?

It's a not very well kept secret that the whole world is going bonkers over wheel size. Wars are erupting on the internet over wheel size, and now, even within the subset of specific wheel size, wars are brewing over what to call the wheel size.

We can make a case for calling this new (old) wheel size 650b, since that's what it's been called since before any of us were born. And there's history, those cigarette smoking, wine swilling Frenchies from Velo Cross Club Parisien were riding 650b bikes off road since the '50's. Here's a great movie of these guys on 650b bikes:

And as all of us who has ever seen Fox News know, nothing will incite a riot faster than giving the French credit for something (especially if they earned it).

We can make the case for calling it 27.5", since we're pretty set on the other sizes being called 29" and 26". The fact that it doesn't really measure 27.5" doesn't seem to be a big deal to people advocating this size.

Our friend Chipps recommended that it be called "medium". After all, we've got small (26") and large (29") already.

We were thinking of calling it "Taint". Since it 'Taint 26" and it 'Taint 29".

We at Ibis prefer to stay like Switzerland in this, happily neutral, not going to battle but preferring to stay on the sidelines, cut the cheese (so to speak) and open wine bottles with our Swiss Army Knives.

So we'll just call it 650b sometimes and 27.5" sometimes (in the interest of world peace).

Show/Hide the Geometry Overlay

With 140mm Fork

Nominal Size   Small Medium Large X-Large
Seat Tube Length A 15" (38.1cm) 17" (43.2cm) 19" (48.3cm) 21" (53.3cm)
Top Tube Length B 564 (22.2") 587 (23.1") 604.5 (23.8") 625 (24.6")
Head Tube Length C 94 (3.7") 103 (4") 118 (4.65") 134 (5.28")
Chainstay Length D 435 (17.1") 435 (17.1") 435 (17.1") 435 (17.1")
Seat Tube Angle E 71.1 71.1 71.1 71.1
Head Tube Angle F 67.1 67.1 67.1 67.1
Wheelbase G 1098 (43.23") 1119 (44.06") 1140 (44.88") 1161 (45.71")
Standover 715 (28.1") 758 (29.8) 760 (29.9) 770 (30.3)
Stack 571 580 595 610
Reach 371 388 409 418
Bottom Bracket Height 13.5" 13.5" 13.5" 13.5"
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


  • Seatpost Diameter 31.6mm
  • Front Derailleur 34.9mm
  • Headset Mixed Tapered (Mixed Tapered (1.5" EC49 lower, 1.125" ZS44 upper)
  • Bottom Bracket 68mm (BSA) English Thread
  • Chainline 50mm
  • Trail 100mm
  • Axle to Crown geometry is based on 534.4mm

Sorry, no build kit info for the Mojo HDR 650b.

Setup Videos

Setting the correct sag on your suspension bike is a fundamental but super important part of getting the most out of your ride. This video shows you how to achieve a perfectly balanced front and rear end. We show you how on a Ripley, but it applies to any of our dw-link suspension bikes.