Language

Advertising by Adpathway

29 vs 32″ Wheels: Is Bigger Really Faster or Just Marketing Hype?

3 weeks ago 10

PROTECT YOUR DNA WITH QUANTUM TECHNOLOGY

Advertising by Adpathway

32-inch wheels are really starting to gain momentum, and it’s looking like they could become a genuine alternative to other wheel sizes.

This topic tends to spark some pretty divided opinions. On one hand, the marketing narrative says bigger wheels are faster. But dive into the online chatter and you’ll find plenty of people arguing the opposite: that larger wheels make bikes slower, and it’s all just a bike-industry ploy to sell more product.

In this article, we’re going to look past all marketing claims and online debates, and instead use real science and maths to uncover the truth.

We’ll start with how big 32″ wheels really are, and whether short riders can use them. We’ll then find out if bigger wheels are really faster and more efficient, and how their additional weight and size affect factors like speed, acceleration and aerodynamics.

This will be part one of a three-part series: next time, we’ll dive into how larger wheels change the handling characteristics of a bike, including stability, grip, steering, and braking. And in the last article, we’ll explore all the compromises involved in designing a bike that can actually fit these giant hoops.

But first, let’s clear up one of the biggest sources of confusion: what 26, 29 or 32″ wheels actually are.

Wheel Size Is Not What You Think

Wheel SizeRim DiameterOutside Tyre Diameter

26 × 2.40″	559 mm (22.0″)	681 mm (26.8″)
27.5 × 2.40″	584 mm (23.0″)	706 mm (27.8″)
29 × 2.40″	622 mm (24.5″)	744 mm (29.3″)
32 × 2.40″	686 mm (27.0″)	808 mm (31.8″)

The terms 26, 27.5, 29 and 32 inches are really just rough references to the outer diameter of a wheel with a typical tyre fitted. In reality, it’s actually quite rare for a wheel and tyre combo to match those inch numbers exactly.

That’s because tyre width plays a big role – as you go wider, the outer diameter increases. In fact, if you fit a wide enough tyre, you can “balloon” the overall wheel size to the point where a 26″ wheel has a larger diameter than a 32″ wheel.

Wheel SizeRim DiameterOutside Tyre Diameter

26 × 4.90″	559 mm (22.0″)	808 mm (31.8″)
27.5 × 4.40″	584 mm (23.0″)	808 mm (31.8″)
29 × 3.80″	622 mm (24.5″)	808 mm (31.8″)
32 × 2.40″	686 mm (27.0″)	808 mm (31.8″)

In this table, I’ve adjusted the tyre widths of common wheel sizes so that they match the 32-inch wheel diameter.

What’s really interesting is that 32-inch wheels are about the same diameter as most fat bike wheels on the market today. We can thus say that if you’re tall enough to ride a fat bike, which is roughly 155 cm or 5 ft 1, you can fit on a 32er. But whether a small rider can descend a steep and technical trail with big wheels is another matter entirely.

Alright, let’s now dig into the physics behind larger wheels and why they can roll faster and more efficiently, and then we’ll check whether the scientific research backs it up.

Why Are Biggers Wheels Faster?

Better Rollover

Bigger wheels roll up and over obstacles much more smoothly. This is because they have a smaller angle of attack – that’s the angle the wheel has to climb when it meets an obstacle.

When a larger wheel hits an obstacle, it makes contact earlier and begins to rise sooner, letting it roll up and over in a more gradual motion. This makes the bump feel smoother (you experience less of a harsh jolt), more comfortable, and it also means you can carry more momentum after the obstacle.

With the extra momentum and smoother ride, you’ll find it’s much easier to climb steep trails littered with rocks – and it even explains why bikes with 36-inch wheels can practically glide up stairs!

	20mm Bump Contact Angle	60mm Bump Contact Angle	100mm Bump Contact Angle
26 x 2.4″ MTB	19.7° (Baseline)	34.5° (Baseline)	45.1° (Baseline)
27.5 x 2.4″ MTB	19.4° (-1.8%)	33.9° (-1.8%)	44.2° (-1.9%)
700C x 50 mm	19.2° (-2.9%)	33.5° (-3.0%)	43.7° (-3.0%)
750D x 40 mm	18.9° (-4.1%)	33.1° (-4.2%)	43.1° (-4.3%)
29 x 2.4″ MTB	18.9° (-4.4%)	33.0° (-4.5%)	43.0° (-4.6%)
29 x 3.0″ MTB	18.5° (-6.3%)	32.3° (-6.4%)	42.1° (-6.5%)
32 x 2.4″ MTB	18.1° (-8.3%)	31.6° (-8.4%)	41.2° (-8.6%)
36 x 2.4″ MTB	17.1° (-13.5%)	29.8° (-13.6%)	38.7° (-14.0%)

Here’s a table I put together showing some wheel sizes and their angle of attack when rolling over 20, 60, and 100 mm bumps. These numbers are simplistic, as it doesn’t take into account tyre deformation, tyre pressure, and lean angles.

You’ll notice that when you move from a 26-inch wheel to a 29-inch wheel, the angle of attack drops by about 4.5% across all bump heights. And when we jump from a 29-inch to a 32-inch wheel, it gives you almost the same improvement again (~4.2%).

So, if you already know how much smoother and more momentum-carrying a 29er feels compared to a 26, expect a similar upgrade again when stepping up from 29 to 32 inches.

Less Sinking Into Holes

Larger wheels also don’t fall as deeply into holes on the trail. With less vertical movement, you use less energy dropping in and climbing back out of holes, and as a result, you can maintain more speed.

This difference is especially noticeable when you’re riding uphill, where you have less momentum to help you maintain speed.

Perceived Bump Height

	Wheel Rise Over 120.3mm Ramp Length (mm)	Wheel Rise Over 202.6mm Ramp Length	Wheel Rise Over 253.8mm Ramp Length
26 x 2.4″ MTB	22.0 (+10%)	66.8 (+11.3%)	113.5 (+13.5%)
27.5 x 2.4″ MTB	21.1 (+5.5%)	62.2 (+6.5%)	107.6 (+7.6%)
700C x 50 mm	20.6 (+3.0%)	62.2 (+3.7%)	104.3 (+4.3%)
750D x 40 mm	20.1 (+0.5%)	60.4 (+0.7%)	100.6 (+0.6%)
29 x 2.4″ MTB	20.0 (Baseline)	60.0 (Baseline)	100.0 (Baseline)
29 x 3.0″ MTB	19.2 (-4.0%)	57.2 (-4.7%)	95.3 (-4.7%)
32 x 2.4″ MTB	18.3 (-8.5%)	54.5 (-9.2%)	89.6 (-10.4%)
36 x 2.4″ MTB	16.2 (-19%)	47.7 (-20.5%)	77.4 (-22.6%)

My favourite way to explain wheel diameter differences is with something I call perceived bump height. It’s a way of describing how different wheel sizes feel when they roll over obstacles.

Here’s how it works. A bigger wheel spreads the same vertical rise over a longer distance. So, if we lock the ramp length for a given bump height with a certain wheel size, we can then compare the total rise over that same ramp length using other wheel sizes.

It sounds complicated, but here’s an example: a 29-inch wheel rolling over a 60 mm bump has a ramp length of about 203 mm. If we use that same ramp length with a 32-inch wheel, it would only have risen about 55 mm after 203mm because of its smaller angle of attack.

So, in other words, a 29er hitting a 55 mm bump should feel just like a 32-inch wheel rolling over a 60 mm bump. Pretty cool, right?

The effect scales with bump size too. A 100 mm bump on a 32er would feel like a 90 mm bump on a 29er. And remember, this works both ways. The same percentage applies when rolling off things: a 100 mm step down on a 32er will feel more like a 90 mm step on a 29er.

So overall, we can say that every bump should feel about 9 to 10% smaller on the 32er compared to the 29er.

Tyre Deformation

The final reason 32″ wheels can roll faster comes down to tyre deformation.

When a tyre rolls, the small patch that touches the ground forms because the casing flexes under load. That flexing costs energy. Every rotation, the rubber and material inside the tyre bend and rebound.

With a larger wheel, the tyre’s curve is slightly flatter where it meets the ground. That spreads the flex over a longer section of the tyre, so it deforms more gradually and loses less energy as it rolls. We’ll drill more into the details of this in part two.

It’s now time to take a look at the scientific research and see whether it supports the idea that larger wheels are faster.

The Scientific Research on Wheel Sizes

Schwalbe Tyres Drum Test

Let’s start with a simple lab test. German tyre company Schwalbe used a steel drum to understand how rolling resistance changes when you use the same tyre model and width, but on different rim diameters.

Their general findings were that rolling resistance consistently decreases as the wheel diameter increases. In fact, a 29″ wheel was found to have around 40% less rolling resistance than a 16″ wheel, which is a huge difference! However, the differences got much smaller when comparing diameters in the 26″ to 29″ range.

These findings are interesting, but they need to be corroborated with outdoor testing as well, so Schwalbe approached the German Sport University in Cologne.

German Sport University Cologne

This private study compared identical bikes fitted with 26-inch and 29-inch wheels using the same tyres. This is one of many tests from the last decade or two, when we saw mountain bike wheel diameters increase from 26 to 29.

Researchers got riders to pedal bikes with both wheel sizes at 20 km/h on three different surfaces, and they found that the 29er consistently rolled with less resistance.

The biggest difference showed up on asphalt and gravel at low pressure (1.5 bar / 21.8 psi). The 26″ wheel bike needed about 214.3 watts to travel at 20 km/h uphill, while the 29er only needed 206.4 watts, roughly 7.9 watts less, or about a 4% reduction in power.

When they bumped the pressure up to 2.5 bar (36 psi), the gap shrank, but the 29er still came out ahead, about 4 to 6 watts less power required across all surfaces, which works out to a 2 to 3% improvement.

University of Pretoria

In our next test, researchers from the University of Pretoria looked at how wheel size affects rolling resistance on different surfaces, using both hardtail and full-suspension mountain bikes (study HERE).

On smooth bitumen, the researchers didn’t find any real difference between 26 and 29-inch wheels. But once the surface got rougher, for example, on grass and gravel, the 29er rolled quite a bit easier, showing around 12 to 15% less rolling resistance.

The biggest difference showed up on the sand. Here, the 29-inch wheels had around 20% less rolling resistance compared to the 26-inch setup.

That makes sense: as a tyre rolls through sand, it’s effectively climbing a small ramp of it the whole time. A larger wheel faces a shallower ramp angle, which means it takes less energy to keep it moving forward.

The researchers also ran a second test. They had the riders hit a 100mm obstacle at a set speed and measured how far the bikes rolled before coming to a complete stop.

The 26er slowed down a lot more – it stopped 15.5% shorter than when there was no obstacle. The 29er only stopped 7% shorter, which means the bigger wheels carried more momentum after the impact.

And here’s a neat detail: rider weight actually makes a difference. If you weigh around 70 kg, the 26er stops about 12% shorter after hitting the bump. But if you’re closer to 90 kg, that jumps to 20% shorter.

So, the takeaway is that the heavier you are, the more those bigger wheels might help you keep rolling smoothly through rough terrain.

Let’s now look at the studies that tested different wheel sizes on cross-country courses.

Swiss Federal Institute of Sports

Researchers took ten elite riders from the Swiss national cross-country team and had them do six laps on a simulated XC course (study HERE). They completed three laps on a 26-inch bike and three on a 29-inch bike.

Half the course was tight and technical, the kind of terrain you’d expect to favour a smaller wheel. The other half was made up of straights and rougher sections that should, in theory, suit a 29er.

Now, here’s where it gets interesting. When the results came in, the 29ers were faster overall, averaging 304 seconds per lap, compared to 311 on the 26-inch bikes (2.3% quicker). And that advantage even held in the tighter, more technical sections.

What’s really cool is that these time gains came without any increase in measured effort. The power output and heart rate were basically identical. So, it appeared the larger wheels were simply more efficient, rolling faster for the same amount of work. In addition, most riders rated the 29″ bikes as the better performers, especially when hitting obstacles.

Southern Utah University

Another study from Southern Utah University found an even bigger difference in performance on their 6.7-kilometre test loop (study HERE). Unlike the Swiss race-pace trial, riders here were asked to maintain a steady, sub-maximal effort.

At comparable work rates, the 29er delivered some clear advantages: the average speed was 6.8% faster, with a heart rate that was about 5% lower. On top of that, the total energy expenditure was 9.4% lower on the 29er compared to the 26er, with the biggest gains appearing on the climbs.

Massey University

A different study from Massey University had participants complete a lap of their test course at full race pace (study HERE).

The results showed that riders were slower on 26″ wheels, finishing in 635 seconds, compared to 617 seconds on 29er wheels – a 3% faster time. This improvement came without any significant differences in power output or heart rate between the two setups.

University of Central Lancashire

And finally, the only study I found showing no statistically significant difference between wheel sizes was conducted by the University of Central Lancashire (study HERE). In that experiment, nine competitive male cyclists each completed a 3.48 km trail loop as fast as possible, using bikes equipped with 26″, 27.5″, and 29″ wheels.

On average, the 29er was about 1.3% faster than the 26-inch bike and required 6.7% less work on the climb. But despite those small gains, the researchers concluded that there were no statistically significant differences between the three wheel sizes in any of the measured performance metrics.

Looking at the broader picture, the scientific data consistently show that larger wheels roll faster and more efficiently. Most studies focus on 26″ vs 29″ wheels, so we don’t yet have definitive proof for 32″. But there’s no reason the same physics wouldn’t carry over, as long as the bikes share similar geometry, stiffness, riding position, and tyres.

Let’s now use physics to see how 32″ wheels will affect weight, speed, acceleration, and aerodynamics.

How Much Heavier Are 32″ Wheels?

I was actually quite surprised when I ran the numbers on how much weight you add when you scale up to bigger wheels.

The tyres make up the biggest jump at about 91 grams each (Maxxis). Then you’ve got the rims, adding 65 grams each, the larger rotors at 56 grams each, the spokes at 32 grams, and just 6 grams for the slightly wider rear hub. Throw in a bit of extra sealant, maybe 50 grams, and around 100 grams more for a longer suspension fork. The total is about 600 grams of extra weight.

Now, you might be wondering about the frame weight. I found the weights of a 26″ and a 29″ Scott Scale hardtail frame, and the difference was only 61 grams. There’s probably a bit more weight required for a 32er, as the frame needs to handle slightly higher forces.

But in total, once the frame and components are truly optimised, we can say it’s less than one kilogram (2.2lb).

Does a 32″ Bike’s Weight Affect Cycling Speed?

Now that we have an idea of how much extra weight we can expect on a 32″ bike, let’s see what the time differences would be over a 50 km long cycling course with 1kg extra weight.

Let’s assume a rider is 80kg and they can sustain 200W power output. Their 29″ bike is 11.5 kg, the 32″ bike is 12.5kg. Both bikes have the same rolling resistance and aerodynamics for this simulation that I calculated using Bike Calculator.

Over 50km of cycling and 500m elevation gain, the 1kg heavier 32″ bike would be about 27 seconds behind, which is 0.4% slower. This jumps to 56 seconds behind with 1000m elevation gain over 50km, or 0.6% slower.

So even on a climb-heavy route, the rider on the larger wheels would only need to roll about 0.4 to 0.6% faster to neutralise the extra weight. That’s a very small margin, and well within the performance gains seen in the scientific tests.

Now, what about acceleration with the heavier wheels?

How Much Slower Do 32″ Wheels Accelerate?

32″ wheels are heavier and therefore require more energy to accelerate them to the same speed as a 29″ wheel. The good news is that once rolling, it’s not more taxing to sustain a 32″ wheel.

In terms of acceleration time, an 80 kg rider on a 12 kg bike producing 500 watts would go from 0 to 20 km/h in 2.94 seconds with 29-inch wheels and 2.97 seconds with 32-inch wheels. That’s a difference of just 0.03 seconds, or about the amount of time it takes to blink your eyes. Basically, nothing.

A rider on a 29er would need to accelerate 33 times at 500 watts before they’d be a full second ahead of the rider on the 32-inch wheels.

So, yes, smaller wheels are faster and more reactive under acceleration, but in terms of time, the difference is smaller than you’d think.

How Much Less Aerodynamic Are 32″ Wheels?

At higher speeds, wind resistance can make up around 80% of the total resistance you’re fighting, so it’s an important factor for us to consider.

A 32-inch wheel adds about 9% more frontal area than a 29er, and the matching fork about 7%. But when you plug those numbers into the drag equation with your body included, the effect is surprisingly small, because your body makes up most of the total drag.

Switching from 29″ to 32″ wheels will probably add around 5 watts of aero drag at 30 km/h, assuming your position and Cd don’t change (they will!). And at typical mountain-bike speeds, it’s more like 1 or 1.5 watts.

Not nothing, but small enough that it could be offset by other wheel advantages.

Summary

Ultimately, the scientific research suggests lower rolling resistance and higher efficiency for bigger wheels, especially on rougher surfaces. That means more speed for the same or less effort.

Yes, bigger wheels are a bit heavier, slower to accelerate, and less aerodynamic, but in many cases, these factors can feasibly be offset by the lower rolling resistance.

In the next article, we’ll investigate the handling characteristics of larger wheels, including how they affect balance, grip, steering, and braking. And in the last article, we’ll explore the compromises involved in designing a frame that can actually fit these giant hoops.

Read Entire Article