In the world of MTBs, as soon as a trend is identified, it gets pushed to the limit. Whether it makes sense or not often doesn’t matter. Only when reality strikes in the form of confused customers, a lack of spares and incompatible “standards” does reason slowly return. But by that point, the damage is usually already done.
And now? Are we seeing another market bubble forming with 32-inch wheels? Or are we witnessing a real revolution that will fundamentally change MTBs for good and eventually spill over to the gravel scene like much of MTB tech?
A Brief History of MTB Wheel Evolution and Its Adoption for Gravel
Until the mid-2000s, the MTB world was still fairly straightforward: 26” wheels were once the gold standard. But with the rise of 29-inch wheels in the XC-race segment, based on 700c wheels from the world of drop bar bikes, things began to shift – initially, mostly on hardtails. By the end of the decade, the first full-suspension bikes with big wheels followed. However, their geometries were often unrefined, tire clearance was limited, components weren’t convincing – and the MTB scene wasn’t quite ready to embrace the new look.
This led to a countertrend: 27.5” wheels entered the picture – closer to 26 than 29 inches. For a short time, it looked like this middle ground would win out. But with the disappearance of the front derailleur, the adoption of sensible thru-axle standards, the refinement of modern geometries and the clear advantages of bigger wheels, 29” ultimately took over.
However, these 27.5” or 650b wheels eventually spilled over to gravel bikes since wide 27.5” tires inflate to about the same diameter as a skinny 700c model, offering more damping and grip without requiring a massive change to established drop-bar geometry. Today, you will still find many gravel bikes with 650b wheels.
Oversized wheels bigger than 29” used to be the domain of custom builders serving very tall riders – like US brand DirtySixer, which builds bikes for NBA players. However, on April 1, 2016, FOCUS Bikes presented the “BIG BIRD 36” – an April Fools’ joke that got plenty of attention. The concept likely drew on wheels from the unicycle world, where 36” rims have been in use since the early 2000s, and 32” formats have existed since the 2010s.
In the past two years, the topic has gained momentum in the MTB industry. The first 32-inch prototypes have been in use since 2025. And, as we have seen, anything that happens in the MTB world is relevant to gravel bikes as they often adopt the same tech in a slightly altered version adapted for gravel bikes.
What Are the Actual Dimensions We’re Talking About?
With the larger wheel diameter, the outer circumference grows by around ten percent from 29 to 32 inches. It’s worth noting that the inch measurement in this context is only an approximate value, as it refers to the outer diameter of the tire – which varies depending on the internal rim width, tire width and, of course, tire pressure. That’s why it’s more meaningful to compare dimensions based on the tire’s inner diameter. This is standardised according to ETRTO and refers to the diameter at the point where the tire sits on the rim.
Here’s an overview showing the increase in tire inner diameter from one wheel size to the next:
| Wheel size | Tire inner diameter | Increase |
|---|---|---|
| 26” | 559 mm | – |
| 27,5” / 650b | 584 mm | 4,47 % (26” → 27,5”) |
| 29” / 700c | 622 mm | 6,51 % (27,5” → 29”) |
| 32” | 686 mm | 10,29 % (29” → 32”) |
Interestingly, the jump from 26 to 27.5 inches is smaller than the step from 27.5 to 29 inches. The next leap – from 29 to 32 inches – would be significantly larger again and roughly equals the total increase from 26 to 29 inches. The same applies to weight: the new MAXXIS Aspen 32 × 2.4″ reportedly weighs 830 grams – around 70 grams more than the 29″ version. The weight difference in the wheels themselves is likely similar: rims and spokes weigh about ten percent more.
The Theory: Rotating Mass, Rollover Behaviour, and Contact Patch
Rotating mass
Obviously, a 32″ wheel is heavier than a 29″ wheel, and its mass is centred further from the axle. This means that it takes more force to speed it up or slow it down. Since the radius contributes quadratically to the moment of inertia, resistance increases sharply with size. To achieve the same braking performance, you’ll also need larger brake rotors.
On gravel, this translates as follows: the larger wheel accelerates more slowly, but retains momentum better through potholes and braking bumps. Depending on your riding style and terrain, that can be either a pro or a con.
Additionally, the greater rotating mass generates stronger gyroscopic forces. These forces stabilise the bike’s direction of travel and make it track straighter and more calmly at high speeds – a definite plus on fast descents and long straights. On the flip side, the increased gyroscopic effect makes quick direction changes harder and steering more sluggish.
Rollover behaviour
Bigger wheels roll over obstacles more easily. The attack angle becomes shallower, which reduces hang-ups on sharp edges. The result: more comfort and the ability to carry speed better on rough gravel.
There’s also the effect of a lower body position relative to the wheel axles, which further improves composure.
Contact patch
A longer contact patch improves grip and cornering stability, especially on loose ground or during climbs. The bigger footprint also allows you to run lower tire pressures, as the load is distributed over a wider area. According to the SRAM AXS app, the manufacturer recommends around 10% less air pressure when switching from 27.5″ to 29″ tires, for example. This increases grip even further.
Lower pressure also brings another benefit: the tire can conform better to the terrain and effectively “wrap” around obstacles. That improves traction and comfort, but also slightly increases rolling resistance.
Overview: Pros & Cons
| Pros | Cons |
|---|---|
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The Cascading Effects of Bigger Wheels on Bike Geometry
Increasing wheel size on a bike isn’t as straightforward as it might sound. A larger diameter wheel has a cascade of effects on the whole bike’s geometry and therefore its handling. The bottom bracket height will either increase, lifting the rider higher off the ground and making the bike feel slightly top heavy, so the bb drop will need to increase, resulting in a lower riding position relative to the axles, thereby increasing stability. Bigger wheels also increase the fork’s trail, which leads to less responsive steering. This can be a positive thing on long sections of straight gravel roads.
Another critical point: chainstay length and frame clearance. Bigger wheels require longer chainstays to provide the required tire clearance, which further slows the bike’s handling. Tucking the rear wheel close to the BB also creates clearance issues with the chainring, which means the drive-side chainstay will have to be dropped if you want to keep the chainstay length to a minimum. Either that or 32″ gravel bikes will be specced exclusively with 1x groupsets. Toe overlap will likely be an issue with such a large front wheel, too. Finally, increasing bb drop increases the cockpit height relative to the rider, as such, the head tube might need to be shortened to maintain the same riding position.
Ultimately, sizing up to 32″ wheels will require a lot of trial and error in finding the right balance in the bike’s geometry and resulting handling. Overall, it will probably come at the cost of agility, making the bike more stable and possibly cumbersome, though it could be a welcome tradeoff in certain scenarios like long gravel rides on never-ending straights, which also plays to the strengths of the wheels’ increased rotating mass.
The Need 32″-Specific Components
Beyond the obvious new wheels and tires, one key question remains: will other components also need to be adapted for 32″ bikes? In short, partly yes.
Suspension forks
Suspension forks will definitely need to be adapted, requiring a completely new casting for 32″, typically made from magnesium. The tooling for this is extremely expensive. That’s why current prototypes on MTBs all use upside-down fork designs, which can be modified from existing 29″ forks relatively easily. For early development stages, they are the pragmatic choice.
Gear ratios
Adjustments in this area will also be inevitable. The increased moment of inertia of larger wheels alone calls for smaller chainring sizes. The increased diameter of the wheels also lowers the effective gear ratio. Technically, though, that shouldn’t be a problem as smaller chainrings already exist.
Wheels
It goes without saying that bigger wheels will require new rims, spoke lengths and tires. Unless this trend takes over, the choice of rims, spokes and tires will be limited, especially as this is a mostly MTB trend for the time being. Therefore, you’ll have a hard time finding the right tires, there’ll hardly be any gravel-specific lightweight carbon rims available, and spokes will be hard to come by too. There will be little or no options of upgrading your wheels and repairs will be difficult.
Racing as an Innovation Driver
What influence does racing have? A huge one! If top riders are faster with new equipment, they’ll demand it. While the pressure in MTB isn’t quite as intense as on the road, the logic remains the same: if a team costs several million euros, €100,000 in development costs can feel like peanuts. And if racers truly go faster with a new setup, there’s a good chance it will make it into production.
Especially in MTB, XC and DH, racers have the greatest leverage. In downhill, there are already rumours about 32/29″ mullet setups. And in cross-country? Things have already progressed further: the first training sessions with 32” wheels took place this year in the Cross-Country World Cup – and it’s quite possible we’ll see them in regular use by 2026. What gets tested in races today could reshape the MTB market tomorrow, and then it will just be a matter of time until we see the first 32” gravel bikes. That said, the UCI might put a stop to that at official events. At least at first.
The OEM perspective: Opportunities and risks
The concept makes most sense in the ultra-distance and adventure gravel segment where you benefit most from stable handling, momentum, and improved rollover behaviour. In all other situations, the added rotating mass significantly affects acceleration, and the handling could feel too cumbersome. You also get a heavier bike overall.
If a mid-range gravel bike priced over € 5,000 ends up weighing 9 kg instead of 8 kg, there will be backlash. There’s also the issue of rising prices. Introducing a new wheel size means low production volumes for tire, fork and wheel manufacturers. That leads to more variants, higher tooling costs, added operational complexity and increased warehousing – in short: it won’t be cheaper or lighter.
This development is hitting a market where sales of traditional pedal bikes are steadily declining. Brands with strong racing backgrounds – like Cannondale and BMC – are under pressure to deliver real innovations. A new wheel size could potentially offer greater benefits than trying to shave off a few more percent in weight.
Our conclusions about 32” wheels
Revolution or just the next market bubble? Fortunately for the gravel scene, the MTB world will serve as the initial testing grounds for now. It will take a lot of trial and error to adapt them for gravel bikes, and gravel bike brands would do well to learn from the mistakes made in the mountain bike sector during the rise of 29” wheels. Back then, the 29ers’ breakthrough was held back by a host of technical setbacks. But are the advantages of 32” enough to spark a new wheel revolution and risk damaging the gravel scene’s goodwill like the introduction of 29” wheels and countless new standards did to mountain bikers? Perhaps for certain niches, like ultra-distance racing where the advantages outweigh the drawbacks, but only if racers are truly faster on the new format. For adventure riders, the lack of spares will most likely put them off.
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Words: Reynaldo Ilagan Photos: Diverse