Sonder Bikes
After the frame, wheels are the single most impactful upgrade you can make to a bike. Here's why that is, and what moving from Sonder Nova to Alpha actually gives you.
Ask most cyclists what they'd upgrade first and they'll say groupset or tyres. Wheels tend to come later in the conversation. That's a mistake.
After the frame itself, wheels are the single most impactful upgrade you can make to a bike. Weight saved, performance gained, the way the bike feels to ride: all of it shifts. Anyone who has swapped a heavy wheelset for a quality one will tell you the difference is real from the first ride.
Here's why, and what upgrading from Sonder Nova to Alpha actually gives you.
Why it matters — the short version:
- Rotational weight at the rim costs more energy to accelerate than the same weight on the frame. Lighter rims feel faster even at the same total bike weight
- A stiffer rim transfers more of your pedalling effort into forward motion; a flexy rim absorbs some of it before it reaches the road
- Hub engagement speed determines how quickly power resumes after freewheeling. Ratchet-ring hubs like the Sonder Black respond more instantly than standard pawl systems
- Double-butted spokes handle fatigue loading better than plain gauge, staying true for longer and reducing maintenance over time
- Upgrading from Sonder Nova 650b to Alpha 650b saves 280g from the wheelset. The equivalent weight savings on a carbon frame would cost a heap more than that.
- These gains compound on longer rides; the difference is most noticeable on repeated climbs, technical terrain, and sustained efforts
Why wheels make such a difference
A bike has two kinds of weight: static and rotational. Static weight is everything that sits still: frame, saddle, bottle cages. Rotational weight is the weight that spins: wheels, tyres, cranks.
Rotational weight costs you more. Every gram on a spinning wheel has to be accelerated not just forward but through a circular arc, meaning it takes more energy to get up to speed and more effort to hold that speed through corners and climbs. Reducing rotational weight (particularly at the rim) has a proportionally greater impact than reducing the same amount of static weight elsewhere on the bike.
This is why wheel upgrades feel so dramatic. You're not just making the bike lighter. You're making it feel alive.
Rotational weight: why 100g on a wheel beats 200g anywhere else
The further a mass is from the axle, the more energy it takes to spin. Rim weight sits at the outermost point of the wheel, the worst possible place for rotational inertia. Saving 50g at the rim has more impact on how the bike climbs and accelerates than saving 100g from the frame.
On a long gravel day with repeated short climbs and technical sections, this compounds. The wheel that accelerates easily out of a corner costs less energy than the one that doesn't. Over five hours, that adds up.
Rolling resistance and rim stiffness
A stiffer rim transfers power more directly. When you sprint or climb out of the saddle, a flexy rim absorbs some of that effort before it reaches the road. A stiff rim delivers it.
Rim stiffness also affects tubeless performance. A more consistent rim profile holds tyre bead more reliably, allows lower pressures without the risk of burping, and maintains a better contact patch across varied surfaces.
Premium alloy rims (like the KLM41 used in the Alpha) are stiffer for their weight than standard 6061, which means the same strength at lower mass. Alpha rims are stronger, lighter, made with tighter tolerances with a better quality finish than the Novas.
A stiffer rim also translates into more predictable handling. On rough gravel or trail sections, a flexy wheel deflects slightly with each hit, which introduces small, cumulative steering corrections. A stiffer wheel holds its line better through loose surfaces and feels more confidence-inspiring in corners — the kind of reassurance that lets you commit rather than hesitate.
What makes KLM41 different from standard 6061
Both are aluminium alloys, but KLM41 is a higher-specification variant within the 6061 family. The difference comes from tighter control of the alloying elements (magnesium and silicon) and the heat treatment process, which produces a higher tensile strength. That extra strength allows the rim wall to be made thinner while maintaining the same structural integrity. The weight saving comes from the rim wall itself, not from compromising anywhere else.
Hub engagement: the difference you feel every ride
Hub engagement is how quickly the drivetrain picks up when you start pedalling again after a freewheel. A slow-engaging hub has a small dead spot, a fraction of a rotation where your power goes nowhere. On flat smooth roads it's barely noticeable. On technical gravel, tight switchbacks, or mountain bike trails, it matters constantly.
The Sonder Alpha uses a 4-pawl freehub with a 30-tooth ratchet ring. The result is fast, positive engagement. The wheel responds the moment you put the hammer down, with no wasted watts on rocky descents where you need instant power to clear an obstacle.
How a ratchet ring hub differs from a standard pawl freehub
Most freehubs use three or four spring-loaded pawls that snap into a star-shaped ratchet. Under load, those pawls carry everything between them. A ratchet ring system (as used in our top range Sonder Black line uses two toothed rings that mesh together when you pedal. The load spreads across multiple teeth simultaneously rather than concentrating on a few small pawl tips. Over time and hard use, this distributes wear more evenly and keeps engagement consistent. When a standard pawl hub starts to feel sluggish, it is usually the pawl springs weakening. A ratchet ring hub degrades more gradually and is simpler to service in the field.
Quality hubs also contribute to braking consistency. Nova hubs are cold forged while Alpha hubs are CNC'd making them stronger, lighter, with higher tolerances and better finish. With disc brake setups, a well-built hub maintains rotor alignment more reliably over time, reducing the chance of rub or uneven pad wear. Riders on rough or mixed terrain often notice that upgraded wheels give more predictable, confidence-inspiring brake feel in wet and muddy conditions.
Spoke quality: the unsung variable
Most riders never think about spokes. They should.
Plain gauge spokes (straight, same diameter throughout) are heavy and lose tension more readily over time. This means wheels go out of true faster and need more maintenance.
Double butted spokes are thicker at the ends (where stress concentrates) and thinner in the middle (where flexibility helps absorb road vibration). They're lighter, stronger under fatigue loading, and hold tension better. The wheel stays truer for longer and rides more smoothly.
The Alpha uses Sapim double butted spokes throughout. The Nova uses plain gauge. This single difference explains a meaningful part of why Alpha wheels ride the way they do.
Nova vs Alpha: what the upgrade gives you in numbers
The Sonder Nova 650b and Alpha 650b share the same 23mm internal width and tyre compatibility, up to 47mm road or 2.2" MTB. The upgrade is in every other dimension.
| Nova 650b | Alpha 650b | |
|---|---|---|
| Weight (pair) | 2,300g | 2,020g |
| Weight saving | — | 280g |
| Rim alloy | 6061 | Premium KLM41 (6061) |
| Spokes | Plain gauge steel | Sapim double butted |
| Freehub body | Cold forged alloy shell, alloy freehub | CNC machined alloy hub, axle and freehub |
| Rim construction | Sleeved, tubeless ready | Welded, tubeless ready |
280g off a wheelset is significant. To put it in context: saving 280g from a carbon fibre frame costs thousands. Here it comes from a smarter rim alloy, better spokes, and a lighter freehub body, all built into the wheel from the ground up.
Alpha across the Sonder range
The Alpha philosophy runs across all our wheel sizes. Same principles (premium alloy, Sapim double butted spokes, fast-engaging hub) tuned to the demands of each discipline.
Alpha 650b: gravel and road adventure. 23mm internal, up to 47mm road or 2.2" MTB. 2,020g. The performance choice for Camino riders.
Alpha Race (700c): road and fast gravel. 22mm rim depth, 19mm internal, 25–35mm tyres. 1,664g pair. Pillar bladed alloy spokes reduce drag. Built for riders who want a wheel that climbs well and holds speed on the flat.
Alpha 29": mountain bike. 30mm internal, up to 2.8" tyres. Boost spacing, Sapim double butted spokes. 2,100g pair. For riders who want responsive, reliable wheels on rough terrain.
Alpha 27.5": aggressive trail. 30mm internal, up to 2.8" tyres. Boost spacing, same hub spec. For tight, technical riding where quick acceleration and agile handling matter most.
All Sonder wheels are designed, laced and built in our Nottingham factory, with full quality control inspection on every pair. Read more about how we build our wheels.
Is a wheel upgrade worth it?
If you're riding a mid-range bike that came with heavy, basic wheels: yes, almost certainly. A quality wheelset will transform how the bike climbs, accelerates, and handles. You'll feel it on the first ride.
If you're debating between a new groupset and new wheels: ride your bike with the new wheels first. For most riders on most terrain, the wheels will make more difference.
There's also a confidence effect that's harder to quantify but consistently reported. Better wheels make the bike feel more capable — more stable, more responsive, more planted. Riders tend to push harder on climbs, commit earlier to corners, and recover from rough patches with less hesitation. Whether that translates into faster times depends on the rider and the route, but it's a real part of how upgraded wheels change the experience of riding.
The frame defines the character of a bike. The wheels define how it comes alive.
How much can you really expect from your wheel upgrade
As they say 'your mileage may vary.. here are some additional factors worth considering:
- Gains depend on what you're starting from. If your current wheels are already decent, say, a mid-range alloy set that's been properly built, the difference will be real but more measured. The biggest jumps come from replacing genuinely heavy or poorly-made stock wheels.
- Context matters. The advantages of lighter, stiffer wheels show most clearly on longer rides, sustained climbs, and technical terrain. On a flat 30-minute commute, you'll feel it, but less dramatically.
- Tyres and pressure matter too. A quality wheelset with the wrong tyres or pressures leaves performance on the table. The gains from wheels and tyres compound they're at their best together.