Unsprung Heroes: The Dymag story

The world of carbon wheels is as fascinating as it is performance-boosting… something British brand Dymag knows better than most, says John McAvoy.

Proof if it were ever needed that we never actually stop learning, especially if you’re prepared to be a bit nosey and look to spend time in the company of people who are either experts in their field, or just good old-fashioned interesting people…or both. In the case of Dymag wheels, when we at Bathams AJN Racing started using them on our race bikes, it was always a source of curiosity that the British manufacturer of wheels wasn’t the “go to” choice for race teams.

Then, when the team moved to the Superbike class in 2025 with Storm Stacey, it became the first and only team on the BSB grid to be using Dymags, which thanks in no small part to the custom gold finish they supplied them to the team, made them probably THE most talked about wheels on the grid. Of course, Dymag’s willingness to accommodate our request for the blingest of bling colours isn’t the main reason we use them.

During one of my visits to the factory in Chippenham to drop off some wheels for a spruce up, curiosity got the better of me, and I cheekily asked Shaun Golding, who’s running the operation there, if he could show me around. No sooner than I asked the question than a mug of tea was produced and we were stood in a room full of shiny stainless-steel moulds and rolls and rolls of raw carbon fibre, along with Dymag’s longest serving members of staff Mike Wilson.

Before we got into the virtues and processes of making carbon wheels, a quick history lesson from Mike, starting with a fabulous piece of pub-ammo that in all my years of being into bikes I never knew. “Dymag” is derived from “Diecast Magnesium”. Now, if you already knew that then kudos to you, but I didn’t, and as soon as I saw the secret hiding in plain sight, it made complete sense when Mike began by explaining that Dymag’s first wheels were magnesium back in 1974 – a time when motorcycle wheels were still spoked.

By being significantly stronger and lighter than what was available at the time, it’s no exaggeration to say that what Max Bostrom (Dymag’s founder) did in the late 70s and early 80s to the competition wheels market was massive, it’s hard to think of a modern day equivalent in terms of performance gain in a single step.

It only took until 1981 for Dymag to win their first motorcycle championship – the AMA Superbike with Eddie Lawson – with success following in GPs in 1984.

It was the same story in cars too where Dymag did and still do about half of their business. Nigel Mansell won the 1985 F1 World Championship in the Williams on Dymag wheels.

Then in 1995, Dymag became the first wheel manufacturer to produce aftermarket carbon fibre wheels for motorcycles, which they did up until Covid, when pretty much everything in the world ground to a halt. It’s only now that Dymag are making carbon wheels again, but nothing like the ones they made originally. A whole new manufacturing technique compared to the one used on the original carbon wheels – known as the CA5 – is now being used on the new ones that are known as CA5 Evo.

There’s also a new testing technique used in the R&D process too. Back in the early 90s when Dymag were developing their first carbon wheels, a pal of the oracle Simon Hardisty, who’s also been at Dymag since forever, tried them out on his race bike as a guinea pig. They painted them white to hide the fact that they were made form carbon, and after a couple of failures, eventually a design was settled on.

Today, the testing process is a bit more scientific. They have to go and be certified by various agencies to very rigorous standards amongst which a brutal “drop test” is performed, which Dymag will do in house. The new CA5 Evo has had 470Kg dropped onto it and not suffered any form of cracking or delamination, which makes them stronger than Dymag’s forged alloy wheels.

So, if Dymag dived into carbon wheels back in the mid-90s purely in the quest for performance, the switch from magnesium to alloy was pretty much forced onto them. The foundry that they had used since the beginning to cast the magnesium alloy closed in the late 80s, so they had a choice to either call it a day or use alloy, and so they came up with a very unique and clever manufacturing technique for their alloy wheels.

All the rims are, by definition, the same; they’re all 17” diameter and either 3.5”, 4”, 5”, 5.5” or 6” wide. It’s the hubs that are the bespoke part to the bike, so Dymag get the rims forged by another company and hold a large stock of them – around 300 at any one time which means a quick turnaround for orders. Then they manufacture the hubs in house and bond them to the rim with a concoction so powerful and expensive that only small batches are ever made at a time so there is no waste. It’s the same stuff that is used to bond the wings to the space shuttle. Once the hub is in the rim, if you needed to separate it, you’d need to heat it to 200 degrees Celsius and have a 3 ton press handy… neither of which is ever going to happen in the real world, let alone both at the same time.

A cack-handed wheelie with a wrist breaking, fork seal bursting heavy landing will produce about 100Kg of shock through the hub/wheel, so nowhere near the 3000KG load needed to separate the hub from the rim, notwithstanding the ambient air temperature will be about 180 degrees Celsius too low.

From a supply, cost and efficiency point of view the technique is genius, and it means that all the important data relating to the hub design is transferable to the new carbon wheels. All they have to do is keep churning out carbon rims, and then depending what orders they get, bond the relevant hub into either their forged alloy rim, or now, the all-new carbon rim.

So, that’s a brief history that brings us to the present day at a time when the latest chapter in Dymag’s story is being written literally right in front of me. Time for some techy stuff…

The original carbon wheel was made using what’s known as “Wet lay” carbon, where literally someone would stand there with sheets of carbon fibre, and dab them with a resin until the desired thickness and pattern was achieved. It worked just fine, and there’s no question that at the time it was cutting edge, but as day follows night, things move on and techniques improve, materials improve and so on.

Back then, the wet lay technique and fibre technology were such that the original carbon wheels had a Tg (Glass Transition Temperature) of 120 degrees Celsius, which is the temperature above which the material might deform. This was OK back then because even if you had tyre warmers, you would never have had them that hot. However, today a tyre warmer at that temperature is not uncommon, so it’s not a surprise that Dymag’s latest carbon wheels have a Tg of 190 degrees – the tyre will melt before the wheel! So, just what makes the new wheel so much different to the original?

The new CA5 Evo wheel is made using a technique called Resin Transfer Moulding (RTM) which is a popular manufacturing technique in composite production these days. It involves the infusion of resin into dry fibre sheets within a closed mould. The process offers precise control over resin distribution which in turn allows for the creation of complex shapes while maintaining structural properties.

It also allows very deliberate use of different types of carbon in layers to give both structural and visual properties, much like how a tyre is constructed using layers of aramid at different angles and thicknesses, then multiple and different layers of rubber to give the tyre its properties depending on whether its asymmetric, multi-compound, for lap times or mileage.

Seeing how a different much thinner sheet of carbon is used for the outer layer – the bit you see – then followed up with a different multi-axial type of carbon weave layered in different aspects to itself in places and thickness reminded me a lot of how a tyre is made.

Much like a tyre, once it’s all assembled in the mould, it’s time for some chemistry and it’s all sealed and subjected to a vacuum while the resin is injected, then it’s all baked at an undisclosed temperature for an undisclosed amount of time… twice.

Call me a nerd, but this kind of stuff is right up my street, and I ask about how much they have had to adapt the design of their wheels as the performance of the bikes has increased over the years, and of course, that’s the wrong question. It’s the advances on tyre performance that Dymag keep an eye on, which of course totally stands to reason. The higher the loads that a tyre can sustain as they evolve means that the one and only component that they are attached to also must be up to it.

I recall a couple of years ago interviewing Pierro Taramasso who is the head of Michelin motorsport about the tyres that they make for MotoGP. He was cursing the advances being made in the aerodynamics of MotoGP bikes as they are now the principal driver in how they design tyres, now that they are seeing up to 400Kg of aero load now being produced for each tyre to cope with. More grip = more load through the point of contact between tyre and rim, which is why it’s that area which sees the thickest section of carbon on the rim.

Dymag have dropped 470 kilos on top of their new carbon wheel with no delamination. Even their forged aluminium wheel can buckle with that amount of weight dropped onto it, but not so much that you’d get a catastrophic loss of tyre pressure, so you could still bring the bike to a safe stop if you did hit a pothole that hard.

The visual layer of carbon does bring some structural stiffness to the party, but in terms of the total thickness of the wheel, the bulk of it comes from the thicker multi-axial sheets of which there will be up to five layers of. However, Shaun and Mike explain to me that the latest trend – mainly in the USA – for so called “Forged” carbon is, in basic terms, just pieces of carbon fibre all chopped up and layered randomly on the sheet and not weaved at all. Therefore, the main purpose in “Forged” carbon’s life is to be cosmetic, while behind it the trick multi-axial woven carbon does all the actual work.

Once the rim comes out of the mould, it then goes into another part of the factory where there’s a line of CNC machines which will trim all the excess resin off and drill any holes needed, which in the case of a motorbike wheel really just means somewhere to put the valve. In the case of some of the car wheels that Dymag are now making, there’s a bit more to it as they have a hybrid carbon/alloy wheel in the car range which is incredibly trick.

Then the next thing is to bond in the alloy hub which is made on site in one of the busy CNC machines, and then you’ve got a bike specific carbon wheel ready to transform the handling of your bike. It’s a well-documented and proven fact that by reducing the rotating mass of a wheel, it dramatically speeds up the rate at which your bike can turn. What’s not often mentioned is how by reducing the unspring mass of a bike – anything that’s on the tarmac side of the suspension – also makes the work of the suspension a lot easier and accurate.

There are literally no downsides to using carbon wheels, and now that things have moved on, not just for Dymag in the arena of carbon fibre technology, I can only see it becoming increasingly more common to see carbon wheels on bikes, especially when you realise that the price gap between forged alloy wheels and carbon ones is closing all the time – a set of carbon wheels are about £350 more than the equivalent set of forged alloy UPX7 wheels.

Of course, it’s not just all carbon wheels now at Dymag, far from it. Their forged alloy wheels have been their staple for decades since the closure of their magnesium forge effectively forced them into using alloy instead of magnesium. That, and the fact that alloy is a far more durable material than magnesium. Magnesium alloy is a highly unstable material and reacts badly to moisture, salt and grime, all of which are in an abundance on our roads and racetracks. In short, unless they are properly treated at the point of manufacture with a protective coat AND maintained meticulously, they will eventually lose their integrity. So, the move to alloy was always the right one anyway.

That said, for an example of how if looked after correctly magnesium can stand the test of time, look no further than the Wiz Norton machine at the Classic TT. The guys from Wiz Norton bumped into Shaun in a bar at Douglas during the Classic TT and upon learning that he works at Dymag, invited him to inspect the period magnesium Dymag’s in their race bike. Much to Shaun’s delight, the wheels were in as perfect condition as they were the day they left the factory back in the 90s, in no part due to how much care they have heaped on them during and since their manufacture. 

For me, as an outsider looking in, there’s a real feeling of going full circle at Dymag. I suspect those that work there won’t see it the same way, they’re an engineering firm with eyes only on the future and how to move forward… but hear me out. They started out making wheels totally in-house, designing and die-casting magnesium wheels themselves in their own foundry, machining them, distributing them and in the process moving the needle on what was accepted at the time as the “best”. They literally went from nothing to the most in demand wheels for race teams of the 4-wheel and 2-wheel varieties all over the world.

Then through a set of circumstances outside of their control, they were forced to adapt and come up with a different concept that meant outsourcing some of their manufacturing process. That didn’t stop them innovating and they also came up with the first aftermarket carbon wheel for a motorbike, a project that also came to an abrupt end once again due to reasons out of Dymag’s control.

However, today they’re now back in the business of making complete sets of wheels totally in-house with the holy grail of materials, just as they were in the beginning. Not just that though, they are using the bonded hub concept that they were more or less forced into coming up with when they lost their own foundry and were faced with either extinction of re-invention.

Walking through the place, I imagine that while obviously the surroundings and machinery would have been a lot different, and the health and safety provisions a lot less/non-existent back in the beginning. The buzz that’s in the air and the passion that everyone I spoke to there have when they talk about their new carbon wheels is palpable. It’s really not a big stretch of the imagination to think that’s exactly how it would have been back in the 70s when there surely must have been a similar buzz about this new innovation called diecast magnesium wheels. Or, as we now know it, Dymag wheels.