The Ibis family of wider is better wheelsets has just grown to 9 different models, including two extremely affordable aluminum options.
New offerings in carbon include the 742, 942, 735 and 935.
The aluminum wheels are called the 738 and 938.
Pro Tip: For all our wheels the first number indicates the wheel size, 9 = 29”, 7 = 27.5”.
With the 742/942, we’ve retained the 41mm outer/35mm inner widths of our 741/941 rims, while increasing impact strength, reducing weight and maintaining all-important lateral stiffness.
The 735/935 feature 35mm outer and 29mm internal rim widths. The 735/935 are ideal for lighter trail bikes that see more XC time, and also great for riders looking to save as much weight as possible, while taking advantages of the features that wide rims bring you.
Our new carbon rim design features a lower cross section height for increased impact performance. The lower 19.5mm section height makes the wheel better able to distribute the loads of localized impacts from rock strikes or hard landings.
Also, we are introducing a new hybrid carbon fiber layup, strategically combining layers of a new, high-toughness carbon/epoxy prepreg with our original carbon composite, increasing both ultimate strength and impact durability. This, combined with the asymmetric rim design that features 5mm of offset (2.5mm on 735/935) allows for higher spoke tensions that are nearly equal from one side of the wheel to the other. As a result of all this, the 742/942 nets a 30% increase in impact strength yet a 7.5% decrease in weight, compared to our previous rims.
Our carbon wheels now come with the excellent Industry Nine Torch hubs. The durable hubs are made in the USA in Industry Nine's Asheville machine shop, and feature a 60t ratchet with 6 out of phase pawls that results in a 3º engagement. They are equipped with Enduro bearings and come with either Shimano or SRAM XD drivers.
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.
The 742/942/738/938 rims are ideal for the ultra low pressures (10-18 psi) that we like to run with 2.8 Plus tires (or 18-25psi for 2.25" - 2.5" tires). Running any of our 35mm internal width rims work incredibly well with the new 2.8 Plus rubber we've been riding from Schwalbe and Maxxis. The low system weight of the wheels with these rims and tires combined with the monstrous traction advantage have been a revelation for those who have ridden them.
We've also had great luck with the 3.0 tires on the rims, and our tire manufacturing friends have informed us that there are a lot of new Plus tires in the pipeline.
You can’t have too much traction.
Read a lot more about these rims, the wheels and the story of their development in the tabs up above. Click the chart below to download our wheel spec comparison chart.
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:
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.
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.
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.
Always use a tire gauge to set your pressures. Wide rims give you a deceivingly stiff feel when doing the thumb or finger pressure test. It's very easy to go too low, which can result in easy bottoming and rock strikes.
It's also easy to go too high, particularly on tne plus sized tires we're putting on the Mojo 3 and the Mojo HD3. Believe it or not, we run anywhere from 10 to 18 PSI on the plus tires. With pressures as low as this, you can actually feel a half PSI in pressure change. So it's critical that you get an accurate gauge. We have researched gauges extensively, and found one that works well consistently. You don't have to turn it on or off, and it gives repeatable measurements. We liked it so much we ended up buying a bunch of them. They're not cheap, but they are the best ones we've found. You can get them here in our online store.
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.
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.
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.”
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.”
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.
The switch to carbon fiber as a rim material has allowed us to build a 435 gram 41 mm wide rim, which is lighter than the much smaller and weaker alloy rims it replaces.
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.
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.
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.
Our new carbon wheels feature all the good points about our prior wheelsets, with a few bonus features. The asymmetric design with offset spoke holes allows us to build a wheel with identical spoke lengths on the drive and non-drive side. The spoke tension is evened out between the two sides this way, building a more durable wheel. We are using a new hybrid carbon layup as well, layering a new high-toughness carbon/epoxy prepreg with our original carbon composite, which increases both ultimate strength and impact durability. So they are lighter and they are stronger.
Our new carbon wheels come with the excellent Industry Nine Torch Hubs. The hubs are made in the USA in Industry Nine's Asheville machine shop, and feature a 60t ratchet with 6 out of phase pawls that results in a 3º engagement. They are equipped with Enduro bearings and come with either Shimano or SRAM XD drivers.
The 742/942/738/938 rims are ideal for the ultra low pressures (10-18 psi) that we like to run with 2.8 Plus tires. They also do wonderful things to the performance of a number of 2.25” - 2.5” tires that start with fairly rounded profiles. We run lower pressures in 2.25-2.5” tires with the wider rims as well, in the neighborhood of 18-25 psi depending on rider weight and riding conditions.
We are currently using two different hubs on our carbon wheels. The 942/742/935/735 wheels are build with Industry Nine Torch front and rear hubs as described above.
While they are no longer being produced, the 941/741/928 wheels were built with a DT Swiss rear hub. They have a special 54 tooth ratchet that yields and engagement angle of 6º. These hubs are super strong and like the other hubs, come with either a Shimano or SRAM XD driver. The front hub on our 941/741/928 wheelsets are manufacturered by a small, high end shop in Taiwan, built to our specification.
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.
Our carbon wheels are build in the USA 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.
We use 125kg spoke tension, but anything from about 90 - 140 will work fine. The rim has a very high pull through strength, about 2-3x the strength of the spokes, so high tension is no problem.
We recommend using stainless steel washers between the nipple and the rim. The ones we use are:
The 35 mm internal width 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 wide rims do 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.
The new aluminum wheelsets from Ibis come in both 27.5" and 29" diameters. Both feature 38mm outer and 34mm inner widths. In other words, wide.
The Ibis aluminum wheels are available in Boost spacing. If there is enough demand, we will make them in 100/142 axle spacing. Let us know!
Aluminum wheelset: $549
Aluminum Rim: $99
The rim is our own proprietary tubeless asymmetric profile, is welded 6066 aluminum, black anodized and laser etched (with lasers!).
The wheels feature laser etched Ibis hubs with Enduro bearings, and a 36t ratchet with 4 pawls that yields a 10º engagement. They are available with Shimano or SRAM drivers. Hubs are made to our specification in a small shop in Taiwan. Replacement parts are available on the Ibis webstore.
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.
Proper setup of your wheels is easy and essential to get the best performance. Here is some info that might come in useful.
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. Start with pressures that don't give you problems with narrower rims, and gradually lower the pressure, being sure to check it with an accurate gauge. As with any rim, use enough pressure to prevent the rim from bottoming on rocks.
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. Also, don't trust your floor pump. They are notoriously bad at reading the correct pressure. We have a favorite digital gauge, and you can order one here in our online store.
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.
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.
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:
ERD = A + 2B.
On our Speed Tuned or DT Swiss hubs, run 2 cross, 32h, and the I9 hubs run 3 cross 32h, the spoke lengths are as follows:
Rear: 274L/ 271R
Rear: 293L/ 291R
In our online store you can purchase our blingy decals for our any of our wheels (with the exception of the 928 wheels), available in several different colors:
Instructions on mounting the 941 and 741 decals on the rims can be found on this link. For the assymetric wheels (742, 942, 938, 738, 935, 735) instructions are included with the decal sets.