Each pair of wheels includes four pairs of exclusive brake pads.

Irwin’s 38 and 58mm Carbon Clinchers

I confess to not having heard of Irwin wheels when these two pair showed up for review (despite the company having a 20 year history in cycling). The hubs are Irwin branded, contain hybrid ceramic bearings, use a freehub body with a very high 60 points of engagement and look and feel like a decent hub. The hubs pair up with Irwin skewers, which are also a quality item. My only issue with the hub is the high seal drag in the freehub – a trait I expect to go away with use (in the case of one of the wheels it had mostly disappeared by the end of the test period). The spokes are common with nearly every other highend wheel on the market; the Sapim CX-Ray. In the Irwins’ case there are 20 spokes in the front wheel, laced radially, and 24 spokes in the rear wheel, laced 2-cross.

The only difference between the 38s and 58s is the rim.

Unimaginatively named, pair one are the IC38C (Irwin Carbon 38 mm deep Clincher) while pair two are ICW58C (the extra W is for wide). Both are full-carbon clinchers with a flawless finish to the outer surface of the rim. The decals are quite muted – the better to not clash with any bike’s colour scheme – but also installed perfectly.

Ceramic fibre is infused in the carbon braking surface to prevent overheating.
Ceramic fibre is infused in the carbon braking surface to prevent overheating.

Included with each pair of wheels are the aforementioned skewers, two full sets of brake pads (ie, 8 pads), two valve extenders and a 10-speed spacer ring (so you can put 8/9/10 speed cassettes on the 11-speed compatible freehub body). I used long valve tubes so I didn’t try the valve extenders, but I did use the Irwin pads with each wheel set. Finally, I ran the same tyres on both wheels (the new Schwalbe One which I will review separately in the next issue).

I had a couple of installation issues that were unusual for test wheels in general. Each wheel had a tiny yellow sticker on the top of the rim (almost where the tyre sits) marking the top of the ceramic reinforced brake track. The brake pads have to sit under this line, which required lowering my brake pads a small amount. The other was that the cassette spacer ring has notches in it like a sprocket, meaning it only goes on the freehub in one position (there is a wide spline that only fits in the wide groove) and only one-way (the grooves are asymmetrical to prevent installing loose sprockets inside-out). One advantage of this is that the ring fits snugly on the freehub body and will not fall off accidentally.

With the four wheels up and running, I put the shallower 38s on my bike first. These have a traditional 13mm inside width making them a bit old-school in this day of ubiquitous wide rims. It meant they slid straight into my bike because I use skinny rims still. Despite the listed weight of my personal wheels and the Irwins being the same, the Irwins felt light on the road. Especially in climbing, where they really felt good.

These rims are not fully old-school in shape, however. The taper of the “V” from brake track to spoke holes is very gradual with a moderately blunt edge facing the hub. They proved to be virtually immune to crosswinds, even at 75 kph on a 15% descent on a windy day.

Braking on carbon rims has improved significantly since their inception and Irwin has been improving their production techniques and fabrication process.

At braking temperatures of 180 degrees C, a phenomenon called ‘Glass Transition’ (known as ‘T.G.’) will take place where the resin in the rim would normally start to transit from a solid state to a liquid state. The heat transferred from the braking surface into the tyre and inner tube can rapidly exceed failure point. Irwin’s ceramic fibre impregnated brake track manages heat dissipation and keeps rim temperatures below 130 degrees C. 

The braking was a bit of everything I’d experienced with full carbon rims before. There was a lot of noise initially, fading to less noise with use (but never silent). The brake pads produced an acrid burning smell whenever they got really hot. I was worried that the squeal would turn into grabby or unpredictable braking, but it never did. In fact, I would say this was the best braking I have tried on carbon rims; very controllable and smooth. 

Each pair of wheels includes four pairs of exclusive brake pads.
Each pair of wheels includes four pairs of exclusive brake pads.

The 38 freehub started out almost silent. As the wheels got some use a fair amount of light grease emerged from the seal between the rear hub and the freehub body, the freewheeling noise got louder and the seal drag diminished – perhaps they had a touch too much grease in there from assembly? 

When I swapped to the 58s, I was surprised by how much louder the freehub body was. I used each pair for about the same distance of riding, but the 58 hub never leaked any grease, never got any louder and the seal drag did not diminish during the test. 

The 58s are 5mm wider (18mm inside width) than the 38s. That meant I was able to run 20 psi less in my tyres and still hold the bike up off the road properly. With more vertical sidewalls due to the wider rim the tyre can support more weight at less pressure. 

These rims are much more ‘U’ shaped than ‘V’ shaped with a very blunt inner edge. This is the current trend and it is supposed to make them just as fast while greatly reducing their crosswind sensitivity. My power meter tells me that the 38s are marginally faster than my personal wheels, going slightly faster for the same power and the 58s are somewhat faster again. It was most noticeable coasting down fast hills where I was suddenly faster than people I was the same speed as on my own wheels. 

I also had the opportunity to ride the 58s down a fast hill in the wind. Above 40kph they definitely demanded my attention more than the 38s, but it never moved into the realm of scary. My partner ( 50% smaller than me) rode the Irwin 58s for a few rides and she really noticed the extra crosswind sensitivity – she usually rides 35s. 

Carbon clinchers, ceramic bearings, Sapim spokes … at about half the price of other brands with similar specs? I would suggest that they’re worth considering if you are on a quest for new wheels. I suspect Irwin will become much better known if they continue making such nice wheels.


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