Wheels

Ibis Carbon fiber Wheels and Rims -The New Normal and The New Wide.

Wider rims are better than narrow rims.

A wider rim delivers better sidewall support so in many cases you can run lower pressures in your rubber. Tires mounted on wider rims don’t burp as easily. Lower pressures, even a pound or two, do several beneficial things, including increasing the contact patch, which results in better traction. Running lower pressures on varied terrain actually reduces rolling resistance. Wider rims are stronger and stiffer. With increased traction comes increased braking control.

Welcome to the wide world of Ibis wheels and rims, what we refer to as The New Normal and The New Wide.

The  is a carbon fiber 29er rim with 28mm width that delivers enhanced tire stability and high strength at low weight.

The  and  are carbon fiber 27.5 and 29er rims with monster 41mm widths that deliver super tire stability even with large tires at low pressure.

The  and  are available as optional upgrades on the Mojo HDR 650b and Ripley 29 now, the  is scheduled as an option for the Ripley beginning in June. 

“You can’t have too much traction.”
Ancient mountain bike proverb.

Benefits of wider rims:

  • Dramatically increased traction
  • Reduced rolling resistance
  • Less tubeless ‘burping’
  • Stiffer, stronger wheel
  • lighter than most narrow aluminum rims
  • Better braking control
  • Improved flat protection
  • More predictable feel
  • You can run a lighter tire with similar durability
  • Hookless bead rims are far stronger
  • Easy to mount tubeless with just a floor pump

Read a lot more about these rims, the wheels and the story of their development in the tabs up above.

Back to the top

Your current mountain bike rim is too narrow.

If you look at nearly all other vehicles, the ratio of outer tire width to inner rim width is anywhere from 1.2:1 to 1.5:1.

Here are a few examples:

  • Road bike 1.2: 1
  • Motorcycle 1.3-1.5:1
  • Car 1.3:1
  • Mountain bike 3:1

So you can see that current mountain bike rims are the complete outlier, everyone else is going about this very differently.

Wide rims were present on the earliest mountain bikes. They rode well, really well in fact. Their downside was that they were heavy, and not strong enough. With recent advancements in carbon fiber and tubeless technologies, we’re now able to bring back the advantages of wide rims with none of the downsides.

What follows is a thorough description of the benefits of going to a wider rim.

VIDEO SUMMARY

We've prepared a video animation that illustrates some of the benefits of ultra wide rims, like better sidewall support, enhanced contact patch, improved burp resistance and lower rolling resistance. 

 

 

Dramatically Increased Traction

Wide rims support the tire’s sidewalls better, allowing lower pressures without the tires folding over or burping. This dramatically increases stability and traction. This shows up as faster cornering and braking, better grip in all conditions. How much lower pressure can you go? THIS DEPENDS ON WHERE YOU RIDE. In general, for a given rider, using tires you've used before in a given locale, you will be able to run lower tire pressures with wider rims. How much lower can only be determined through experimentation. If you ride in very rocky terrain, especially terrain with lots of square edged rocks, start with pressures no different than where you ride with narrower rims. Light riders on moderate terrain can oftentimes get away with running 4–6 psi less than normal.

Use a gauge

Always use a tire gauge to set your pressures. Wide rims give you a deceivingly stiff feel when doint the thumb or finger pressure test. It's very easy to go too low, which can result in easy bottoming and rock strikes.

Tires: Go Big, or Small

Big - If gravity is your thing, bigger tires and lower pressures equal more traction. The problem is, you can only go so low with large tires on narrow rims before they become unstable. Enter the wide rim. Select the pressure you want without having to over pressurize the tire  to control stability and burping.

Not-so-big - If you’re leaning more toward XC use, you can actually go down one tire size and achieve the same or higher levels of traction and performance, only at a reduced overall weight.

Less Tubeless ‘Burping’

Wider rims dramatically reduce the incidence of burping. With wider rims the tire sidewall can’t exert as much force on the bead to unseat it and allow air to escape.

Low Pressures Equal Low Rolling Resistance

“Anyone who wants to ride really fast off-road needs to decrease tyre pressure. The rougher the ground, the more pronounced the effect. Traction and comfort increase too.”
Peter Nilges, Editor, Bike Magazine (Germany)

Our wide rim profiles provide better sidewall support, in many conditions allowing you to run lower pressures with no ill effects.

More from Peter’s university thesis:

“Any such unevenness means that part of the forward propulsion force is required to lift machine and rider upwards. This is equivalent to riding a short uphill grade that requires a certain amount of lifting energy. A tyre with less inflation can adapt to unevenness more easily. The total system needs to be lifted to a lesser degree and less frequently. Resistance is reduced, less power is required.”

Read the great article here.

Hookless Bead Rims are Far Stronger

Impact damage is the way most carbon rims die. The rim we’ve designed is much stronger in the area where impacts occur since it's a solid rectangle instead of an inverted "J". This spreads the impact out over a larger area that is also supported by more material.

We tested the impact strength of several major brands of carbon fiber rims and discovered that the change to hookless bead was a major advantage in impact strength. We also optimized the layup to further increase strength. In the end, our rims are 50 to 300% stronger in impact than competing rims we measured. We don’t want to throw anyone under the bus, but we do want you to know that these are well-respected and well-known manufacturers.

Stiffer and Lighter

The switch to carbon fiber as a rim material has allowed us to build a 475 gram 41 mm wide rim, which is lighter than the much smaller and weaker alloy rims it replaces. The 928 is 100g lighter and several times stronger than alloy rims of the same size.

More Predictable Steering

Without wallowing sidewalls, and with dramatic increases in rim stiffness and contact patch area, the front end of the bike feels more precise and firmly planted than it ever did before. The difference is even greater than the improvements that came from tapered steerers and through axles in recent years.

Tire Fit

We’ve carefully sized the bead area so that it’s easy to mount and dismount most tubeless tires by hand. Many tubeless tires will inflate and seat with only a floor pump.

History Repeating Itself

Mountain bike rims were not always narrow. The venerable Araya 7X, a popular rim from the ‘80s, was labeled 26x1.75" and had an inside width of 25mm. That gives a tire to rim inner ratio of 1.78. A 2.35 tire on a modern 19mm gives a ratio of 3.14, even higher than our 3:1 outlier number mentioned above. A 2.35 tire on our 741 rim results in 1.73:1, back to the original Araya number. Read more about the history on the story tab to the right.

Back to the top

About the Ibis Wheels.

  • 41 mm outside, 35 mm inside width, 27.5” / 650b diameter
  • 1650g for the set
  • rim only 475g
  • 32h Hubs | Shimano or SRAM XD driver
  • 15mm Thru-Axle Front (no 20mm adapter)
  • 142x12 Rear (135x10 QR adapters available)
  • Tubeless Ready

  • 28 mm outside, 22 mm inside width, 29” diameter
  • 1580g for the set
  • rim only 375g
  • 32h Hubs | Shimano or SRAM XD driver
  • 15mm Thru-Axle Front (no 20mm adapter)
  • 142x12 Rear (135x10 QR adapters available)
  • Tubeless Ready

  • 41mm outside, 35 mm inside width, 29” diameter
  • 1770g for the set
  • rim only 490g
  • 32h Hubs | Shimano or SRAM XD driver
  • 15mm Thru-Axle Front (no 20mm adapter)
  • 142x12 Rear (135x10 QR adapters available)
  • Tubeless Ready

Ibis will offer these wheelsets as a modestly priced upgrade on our bikes or separately through our dealers at $1299.

Hookless Bead Rims are Far Stronger

Impact damage is the way most carbon rims die. The rim we’ve designed is much stronger in the area where impacts occur since it's a solid rectangle instead of an inverted "J". This spreads the impact out over a larger area that is also supported by more material.

We tested the impact strength of several major brands of carbon fiber rims and discovered that the change to hookless bead was a major advantage in impact strength. We also optimized the layup to further increase strength. In the end, our rims are 50 to 300% stronger in impact than competing rims we measured. We don’t want to throw anyone under the bus, but we do want you to know that these are well-respected and well-known manufacturers.

Spoke Holes

The rims are engineered to be stronger than the spokes so the rim can't be damaged if a spoke gets broken by a stick etc. Each spoke hole is individually reinforced with extra carbon material to achieve this while still building a lightweight rim.

Hubs

We have a small, high end shop in Taiwan make the hubs for us to our specification. We have thoroughly tested and qualified these hubs, working closely with the factory to ensure high performance and durability. The hubs are backed by Ibis’ world class service and all small parts and tools will be made available through our dealers and on our web store. The hubs feature Enduro bearings throughout and a durable and smooth freehub system available with either a Shimano or SRAM XD driver. 

Wheel build

We build with 32 conventional spokes (available at any bike shop) and standard exposed nipples. This allows tuning without special tools or dismounting the tire and rim tape. In our tests we found that although you can reduce the weight by using fewer spokes it hurts the long-term durability and also is more prone to damage from sticks getting lodged between the spokes. A 24 spoke wheel with even 1 broken spoke often can not be ridden as the tire will be hitting the frame. With 32 spokes you have a better chance of riding out after a mishap. The spokes are triple butted 2.2 - 1.5 - 2.0 gauge with 7075 high strength alloy nipples and stainless washers.

What To Expect

The 41 mm wide rims typically increase the tire width about 3 -5 mm at the widest part of the casing. The diameter stays about the same. The shape of the tread cap will be flatter as well.

The 741 and 941 change the shape of the tire and you will want to select a tire that has a good profile on the wider rims. Generally we have found that tires that start with a rounder profile across the tread cap work the best.

Back to the top

A History of Wide (and Narrow) Rims.

In the early 1980’s, when the first purpose-built mountain bike frames (including Ibis!) were making their initial crawl out of the primordial ooze, we had to use already existing components on our bikes. These components were often not as good as they could be, having been adapted from other types of bikes. Sometimes we used parts adapted from motorcycles-such as the Magura and Tomaselli brake levers on our early machines.

One nearly ubiquitous component that nearly all of us put on our bikes were the Araya 7X rims. They were actually a BMX rim adapted for 26” cruiser bikes. While these aluminum rims were fairly wide and rode very well due to their width, their method of construction, a channel section, was neither the strongest or lightest way to build a rim.

Road bike rim manufacturers had already figured out that a box section was a far superior shape and the best rims at the time were made that way.

In the early days, we still can remember mountain bike pioneer Charlie Cunningham, one of the smartest guys in the room, making the case for box section rims for our mountain bikes. He would take any opportunity he could to sketch out the rim that he knew would make for a better performing bike, hoping that someone would eventually make that rim.

Charlie got his wish, sort of, when Keith Bontrager cut down the first Mavic MA2 rims from a 700c rim (or maybe it was that long forgotten 27” rim size) to a 26” rim diameter. The rims were strong, stiff and light, a box section made of aluminum.

What happened in the process though, is that since they started as road bike rims, they were a lot narrower, changing the shape of the tire when mounted on the rims. A number of things happen when you do this to a tire, mostly undesirable. Having a lightweight rim pretty much trumps the rest of those compromises, so we increased our pressure a bit and went happily down the trail for the next 30 years.

Since then, rims got a little bit wider, but not much. Weight (or lack thereof) was still king.

There are exceptions. Downhillers generally use wider rims as they see the benefits of increased control and far superior traction. Wide aluminum rims are heavy though, unacceptably heavy if you ever need to pedal up a hill or accelerate.

We’re not the first people to discover the wide rim advantages. The early mountain bikers as mentioned above had it right. Back in 2011, Richard Cunningham, the Pinkbike.com tech guru wrote an article called “Wider Rims Are Better” in his Pinkbike Tech Tuesday Series. RC had it right, and we encourage you to read the article. In 2012 Richard wrote about the Syntace W35 MX 35mm wide aluminum rims, once again beating the wide rim drum.

In 2013 the first wide carbon fiber rims came out, called Derby Rims. Derby is our good friend and in fact Ibis liked his idea so much we funded half the original tooling expense of these rims. Having access to the Derby Rims proved invaluable in testing for our own concepts and designs. Derby’s rims are made in a different factory than ours, as we will be needing a much larger quantity than his source can provide.

For now, we will only be selling complete wheels, so if you’re looking for rims only, we heartily endorse the product that Derby is selling. If you can get them that is, Derby Rims have been regularly selling out each production run.

If you already own a set of the wheels, here is some info that might come in useful.

Setting Pressure

One of the ways we used to set our tire pressures (when using narrower rims), was to put enough pressure in the tire to avoid burping the tubeless. For the wider rims, you need to adjust your pressure based on rock strikes. These wheels are so effective at anti-burp that it's tempting to put too little pressure in when riding in rocky terrain.  So adjust for your terrain, if it's rocky, you'll need to raise your pressures.

USE A TIRE GAUGE!

The wide rims can deceive you with how much pressure is in the tires. If you're one who normally sets tire pressures by feel rather than by measurement, you'll need to recalibrate! We've seen cases of people who thought they were running 22psi and they actually measured 15psi.

Mounting

The rims are designed to accommodate tubeless or tubeless ready tires. You do not need tubes. Mounting is usually easy, requiring only a floor pump. Sometimes it helps to soften the tires in the sun to make them more pliable and easier to seat.

Once you do get the beads seated, it wouldn't hurt to put 40 psi in the tires overnight. We've found that seating for a time at higher pressure will result in a better seal, and you'll experience fewer burps.

Rim Tape

The blue tape used to seal the rim is from Scotch, and is the best in the business. It seals the spoke holes beautifully, which is all you need to seal. Rim tape is not there to help the tire seat or seal, in fact it hinders seating. The bead seat dimensions on the rim are very precise (molded into place and controlled very tightly) so that the tire/rim interface conforms to a precision standard. We also designed the inner shape of the rim surface (between the bead seats) so be smooth, so that the tape sits between them creating a good seal.

If you do need to replace the tape, there will be very little residue on the rim and you only need to lightly clean the surface first with alcohol. Do not use something like Gorilla Tape on there, it's heavy and falls apart easily, leaving a real mess to clean up. The thickness of it also can make the tires very difficult to mount/unmount.

Ibis Carbon rim ERD

  • 741’s: 541.7mm
  • 928’s: 598.6mm
  • 941’s: 579.1mm

A bit about ERD, from Sheldon Brown's website

Effective Rim Diameter (ERD) is the diameter on which you want the ends of the spokes to lie. Most people prefer it near the end of the spoke nipple. If you want to measure your own rim (recommended, just to be sure), then follow these instructions:

  1. Insert two old spokes into holes exactly opposite each other on the rim. Count holes to be sure.
  2. Screw some nipples onto the spokes.
  3. Pull them tight and measure dimension A in the figure (the diameter to the edge of the nipples, where the spokes disappears into them). Do this at several spots around the rim and average the measurements.
  4. Measure the length of a nipple (dimension B in the figure) and add it twice (once for each nipple). The result is Effective Rim Diameter (ERD). Thus,

ERD = A + 2B.

 

Ibis Carbon Rim Spoke Lengths

741
Front-Disc brake side: 253mm
Front-Non disc side: 255mm

Rear-Drive side: 255mm
Rear-Non drive side: 253mm

928
Front-Disc brake side: 282mm
Front-Non disc side: 284mm

Rear-Drive side: 282mm
Rear-Non drive side: 284mm

941
Front-Disc brake side: 275mm
Front-Non disc side: 277mm

Rear-Drive side: 275mm
Rear-Non drive side: 277mm

Optional Decals

 

In our online store you can purchase our blingy decals available in 5 different colors:

  • Vitamin P
  • Enduro Blue
  • Rip Green
  • White
  • Warm Silver

To get whisked away to see the decals on our store click this link.

If you already own the decals, instructions on mounting on the rims can be found on this link.