Sonder Prima Al 105 Di2

The new Sonder Prima Al is a tight-feeling, nippy aluminium race bike – and is proof that performance and racing don't always mean carbon fibre. It's ideal for entry-level racing or if you want a quick bike for the road without a massive price tag, and I also think it would make a decent all-rounder too, with a reasonable weight for the spec. You do need to watch the cable rub, though, as the paint can scuff quite easily.

> Buy now: Sonder Prima Al 105 Di2 for £2,599 from Alpkit

For more options, check out our guides to the best road bikes and the best aluminium road bikes.

Sonder Prima Al 105 Di2: Ride

While we still see a steady flow of aluminium alloy bikes coming in for review, many are focused on the endurance, all-road or gravel side of things. So when I received the email from Sonder's distributor Alpkit announcing the launch of its new Prima Al race bike, well, I just had to review one.

I think aluminium is a great material for entry- to medium-level racing even in 2024, and as it's generally cheaper than a similarly specced carbon bike, it's a great option if you want a more affordable way into road riding and an aggressive, aero riding position.

Sonder has delivered exactly that. Its Prima Al is a capable road bike in terms of weight, performance and stiffness – and considering the spec the price is very reasonable.

The ride quality is typical of that of a mid-range aluminium frame. Its ride isn't as smooth and comfortable as something higher-end such as Mason's Definition frameset, or the more similarly priced Trek Émonda ALR – but the Prima Al is more than capable of stopping you getting battered over poor road surfaces as the miles mount up. It's by no means harsh, but its firmness is noticeable through the contact points, which provide good feedback without it getting muddied by road vibration and high-frequency buzz.

Tyre clearance is an impressive 32mm, so running larger rubber will help soften the ride a touch should you feel the need. Soft tyres can't mask a poor ride quality – though thankfully here they don't have to.

Our medium size test bike has a wheelbase of just 977mm, which helps to make the Prima Al very nimble indeed, though it does make the bike look very small and compact for its size.

It's worth pointing out that our bike was supplied with an 80mm stem, which was too short for me considering the Sonder's 549mm top tube, so for testing I used a 110mm stem.

Its short footprint, 535mm stack and 390mm reach make for a performance-biased riding position, and with 73.5-degree head angle and 45mm fork offset, the front end feels quick and direct without being twitchy.

I removed one hand from the handlebar while riding at just under 40mph to grab something out of my jersey pocket and the Prima Al tracked wonderfully, which inspired a lot of confidence for high-speed descents.

The tightness and stiffness of the frame and fork also make sprinting and climbing rewarding. The Sonder has one of those personalities that goads you into giving the pedals a stamp, and I think you get a decent return for your input.

At around 8.8kg it's not the quickest out of the bends or off the line, but when you keep things rolling the Prima Al is impressively responsive.

Future upgrades – to the wheels and tyres in particular – would reduce that weight and give you a formidable race machine.

Sonder Prima Al 105 Di2: Frame & fork

Sonder has used 7046 grade aluminium alloy for the frame, which I've seen used before though not as often as 7005 or 6061 – and I couldn't detect any downsides to its ride quality compared to the other two alloys. Sonder doesn't make any mention of any butting (where the tube walls are thicker at the ends for strength, and thinner in the middle) which could explain why the ride isn't quite as supple as that offered by some other aluminium frames.

The claimed 1.4kg frame weight isn't bad overall, and pairing that with a full-carbon monocoque fork keeps the build to about what you'd expect for an alloy frameset at this price.

The welding is reasonably clean and tidy, though bordering on functional in places, and you'll find thicker welds around the bottom bracket area for extra strength. There are also small sections of aluminium welded to the frame to increase stiffness, such as underneath the down tube where it meets the head tube, and at the top of the dropped seatstays.

The Prima Al is available in red or the blue we tested, which I think looks elegant and goes some way to mask the welding.

Sonder hasn't run the hoses and cables through the stem and inside the head tube, preferring to run them externally. But with our bike running an electronic groupset, only the brake hoses were on view anyway.

The rear brake hose and any mechanical gear cables are directed into the frame on the sides of the down tube, exiting just above the bottom bracket shell before running along each of the chainstays.

All good in terms of function, but the electronic groupset on our bike meant that the guides to the rear mech aren't used. Again, it's not a big deal but personally I think that having guides welded to a frame that aren't being used ruins the aesthetics.

Overall though, I still think it is a good-looking bike – if not quite as sleek as some of the competition.

Everything is bang up to date, however, with 12mm thru-axles making wheel upgrades simple, while the frame uses a standard round seatpost and external clamp.

Many will also be pleased to see an external threaded bottom bracket.

The Prima Al is available in four sizes from small to extra-large, which Sonder says covers riders from 5ft 2in to over 6ft2in.

You can find a full size guide on Sonder's website but our medium has a 549mm top tube, 130mm head tube and 500mm seat tube.

The head and seat tube angles are a pretty aggressive 73.5° while the stack and reach figures are 535mm and 390mm respectively.

The chainstays are just 410mm long, which helps to bring that wheelbase down to a tight 977mm.

Sonder Prima Al 105 Di2: Groupset

The Prima Al is available as a frameset for £849 or in a range of builds that starts with a Shimano Tiagra groupset and mechanical braking for £1,449, or £1,599 for hydraulic braking. Splitting those two is the SRAM Rival mechanical build at £1,549.

The model with Shimano mechanical 105, which is my pick of the bunch in terms of value for money versus performance, costs £1,849, while an Ultegra mechanical groupset nudges that up to £2,249 – though that also gets a wheel upgrade.

Models with electronic groupsets top out at £3,149 for SRAM Force AXS, with Ultegra Di2 coming in at £3,049. SRAM's Rival AXS costs £2,649 while the model we have, the 105 Di2, is £2,599.

I reviewed Shimano's 105 Di2 groupset when it was launched in 2022, since when it has become a staple on many mid-range bikes. I think it's a good entry into the world of electronic gearing, even if it's nearly double the price of the mechanical option.

It works very well with a light action and quick shifts – and I'm a big fan. It may not be quite as refined as Ultegra, but not to the point that you'd notice unless you were riding the two side by side.

The 50/34T compact chainset is paired with an 11-34T 12 speed cassette, which gives you a decent spread of gears for fast-paced riding while providing you with a couple of bailout gears when you get to the climbs.

Braking comes courtesy of 160mm rotors that provide plenty of bite for the hydraulic callipers. Shimano has always done the blend between power and modulation very well on its braking systems – and it's no different on this 105 setup.

Sonder Prima Al 105 Di2: Finishing kit

The rest of the components are pretty much all Sonder branded. It's basic, functional and the matt black finish ties in nicely with the frameset's gloss paintjob.

The Sonder Hurricane handlebar has a shallow drop and standard reach, which makes all the hand positions accessible, and it's sufficiently stiff too.

The bar morphs from a round to a flared profile for added hand comfort, though this does limit space for fitting light brackets and computer mounts.

The Sonder Reels tape is comfortable and offers good shock absorbance.

The Storc stem does its job with no fuss and is available in a range of sizes from 80mm to 120mm for no additional cost; you just select the one you want while ordering your bike. And Sonder also offers you a choice of handlebar widths too.

It's the same story with the saddle. You have a choice of Sonder Abode black in two different widths or can upgrade from a number of different choices including a couple from Brooks. Our upgrade to the Sonder Zone saddle added an extra £29.99.

It's quite narrow and doesn't have a huge amount of padding. I liked the shape and it provides plenty of clearance for my thighs, especially when riding in the drops.

When ordering a Prima Al, you can choose to upgrade any of the components, with each option showing how the price affects your overall build.

Sonder Prima Al 105 Di2: Wheels & tyres

The build comes with Sonder's alloy rim Alpha Aero wheels, which have a gloss black finish that makes them look more expensive than their £349 price tag might suggest.

Their 31mm-deep rims have an internal 19mm width and they're designed for tyres from 25-35mm wide.

I reviewed them in 2021 and on the whole I was impressed. I found them tough and durable with smooth-rolling bearings, though weighing over 2kg they are a little weighty.

A £424.99 upgrade – half the RRP – to Sonder's Black i21 Carbon wheelset would knock that weight down to a claimed 1,560g, which would make a noticeable overall performance gain.

Sonder fits a pair of 28mm Goodyear Eagle F1s with WTB inner tubes as standard, though it will upgrade to tubeless for an extra £44.99, which is what we have here.

I found the tyres not only grippy but they also offer a decent balance of suppleness and durability.

Sonder Prima Al 105 Di2: Value

The Sonder measures up pretty well against other aluminium race bikes we've recently tested.

The Trek Émonda ALR 5 I reviewed uses Trek's own Ultralight 300 Series Alpha aluminium for the frame and comes with a full carbon fibre fork. With a Shimano 105 12-speed mechanical groupset and an alloy wheelset it has an RRP of £2,150, £300 more than the Prima Al with an equivalent spec.

Specialized's Allez line-up has shrunk over the years and now numbers just three bikes. The standard Allez is more endurance based than the Prima Al, with the performance end of things taken care of by the Allez Sprint Comp. Liam was impressed when he tested it a couple of years ago, and the latest model comes with Shimano 105 mechanical for £2,600 – the same price as this Di2 Prima Al.

Cannondale has long been renowned for its aluminium race bikes. The current CAAD13 has been with us for a long time now, with Mat having rating it very highly back in 2020. But with a 105 Di2 groupset and DT Swiss wheels it will now set you back a quite hefty £3,250.

Sonder Prima Al 105 Di2: Conclusion

The Sonder may not be the most refined aluminium alloy road bike I've ridden over the last few years. In fact, it has a bit of an old-school feel to it, resembling alloy bikes from, say, a decade ago – but for me that's not necessarily a bad thing. It's definitely a bike that keeps you connected to what is happening between the tyres and the road but it does this without being harsh – and for that I kind of like it, though not everyone will.

But it most definitely has price on its side, coming in much cheaper than those mentioned, so while it may be a little less refined it scores very well on the value front.

It's a good bike overall, with geometry that gives that nippy, aggressive ride that's ideal for entry-level racing or fast-paced club runs.

> Buy now: Sonder Prima Al 105 Di2 for £2,599 from Alpkit

Verdict

Fun, fast and great value, though not the most refined aluminium frame on the market