Carbon wheels have been making inroads in mountain biking for well over 5 years. Although the first options were limited, and eye-wateringly expensive, the options for mountain bikers have grown – there is now so much choice on the market. From major manufacturers like Enve, who keep on expanding their range as the market changes with wider and lighter rims, and smaller boutique manufacturers like Kappius, who offer 30mm wide, and really wide 46mm rims that they feel suit the needs of mountain bikers best. And Light Bicycle have the 28mm wide XC923, which we are going to test.
Carbon fibre wheels aren’t necessarily about being super light. The idea is strength, typically at a lower weight than you might achieve with aluminium. Perhaps the best example of this is the Stan’s NoTubes Valor wheel set, weighing in at a scant 1280g for the 29er wheel set in 15mm front, 142×12 rear combination. The newer models with Neo hubs are a bit heavier – but the lightweight rim has a 21.3mm internal width, a little wider than many standard rims, helping the tyre inflate to a good size with more predictable handling at lower pressures.
All the above wheels come at a price. A price that represents the research, development and warranties that each brand provides. But there are many rims coming direct from China that claim to offer many of the same features, for a much lower price.
Testing the Light-Bicycle XC923 wheel set
There are two main suppliers riders have been turning to for direct purchases of carbon wheels or rims. Nextie, and Light Bicycle. We have run a test on some light Nextie rims before, and will be revisiting these rims soon with a new build. So this time, we wanted to test the quality of the rims, and quality of the wheel build from Light Bicycle.
Light Bicycle have a broad range of rims for road bikes, both tubular and clincher, including tubeless compatible rims. They have carbon fat bike rims, and most importantly they have a variety of carbon mountain bike rims. For 26″, 650B and 29″ wheels, and 650B plus and 29 plus options too. They even have tubular rims if you want to go “full euro”. Pricing starts at about $USD160 per rim and goes up from there.
The XC923 rim is quite new from LB. Much of the details come from the product code. It’s an XC rim in a 29″ size, with 23mm internal rim width, and 28mm external width. The rim size has been optimised for use with a 2.1 -2.35″ tyre, so that is spot on for marathon races and stage races. The rim is also 23mm high, which should mean it is less harsh than taller rims, although it might not look as good in your Instagram photos…
What is really interesting is the offset spoke bed. With the rim holes and rim peak offset by 2mm, the builder can then keep spoke tension more even on the wheel from drive side to non-drive side on the back, and for the disc side and non-disc side on the front. More even spoke tension creates a stronger wheel.
The weight is good too, claimed to be 370g give or take 15g. That is a little heavier than the Nextie 27mm rims we tested previously, which were about 360g per rim. Although they were narrower with a 21mm internal measurement, and are 27mm high.
But, we ordered wheels, not rims. Light Bicycle offer a build service, and we chose 28 holed DT Swiss 240 hubs, and DT Swiss Comp Race spokes and Pro Lock brass nipples. All in, a pretty solid build, and one that should really let us review the build quality, and the rims.
Unboxing the Light Bicycle XC923 wheels
The wheels arrived a little over a week after ordering – but this will depend where you’re based. Shipping was tracked, which was perfect for peace of mind.
The wheels were packed really well, with the ends of the hubs padded safely with dense foam, and the top and bottom of the wheels nestled into custom cut padding.
I’d added LB’s tubeless tape and valves to the list as well – you can never have too much spare tape or valves.
Before putting the tape on, I put the wheels on the scales to see what they ended up weighing.
So a total of 1478g is very respectable for a wheel with brass nipples and not using silly weight spokes, or hubs for that matter.
Setting up the Light Bicycle XC923 wheels
Taping rims isn’t hard, but it really depends on the tape. The tape supplied by LB was quite narrow, but it did stay nicely down in the rim bed. It’s reasonably thick so I think you would have trouble damaging it. The valves are very similar to other alloy valves around, with removable valve cores that can help with inflation, or just getting sealant in.
I mounted my usual setup of a Maxxis Ikon EXO EXC TR 29×2.2″ tyre on the back, with a Maxxis Ardent Race EXO EXC TR 29×2.2″ on the front. Basically that is a fast rolling rear tyre, with a little more tread on the front. Sidewalls are reinforced (EXO), the rubber is a triple compound (EXC) and they are tubeless ready (TR). The rear tyre inflated with a track pump, but I did need to use a CO2 on the front. This was more likely the subtle differences in tyres than the rims. That said I rarely need to go past the track pump when inflating tyres on Valor wheels, and the same for Kappius rims.
It’s a little hard to catch the asymmetric shape in photos, but feeling spoke tension (by hand) it feels very even. More so than on other carbon wheels within the service course.
Riding the Light Bicycle XC923 wheels
The proof is in the ride, right? With centrelock rotors mounted, and an XT cassette on the Shimano freehub, I was off. I had spent the past two weeks on 30mm 32 hole Nextie rims, built to a DT Swiss 240 rear hub and XTR front. I’ve had these wheels for close to 18 months and they’re solid. Not light, but solid. The previous month I was exclusively on my ZTR Valor race wheels.
My first ride was hilly, and with a lot of singletrack. The lower weight from my Nextie wheels was immediately noticeable, as it would be for anyone. But I was also very impressed by how laterally stiff the wheels felt. In no way did the loss of 4 spokes per wheel detract from the ride quality. But the increase in stiffness over something like the Valor was noticeable. Given there is 200g difference that is not surprising.
There’s a lot of talk out there about the right width for rims. It’s a given that wider is better. Why base our rims off standards from road bikes? And even those rims are getting wider! But I have noticed that my 2.2″ Ikon does get a little too fat on a Nextie 30mm rim, with the sidewall bulging past the edge knob. Most XC tyres aren’t yet designed for wider rims, and this can leave the sidewall exposed to more punctures. Plus, it means you can move right past the edge knobs pretty easily. More aggressive tyres tend to deal with it better, thanks to larger side knobs.
The 28mm width with 23mm internal on the XC923 seems to be spot on so far. I run quite low pressures, but below 20psi I burped the rear tyre, so it really is best to not go too low. Keep that for something like the Kappius super wide rims.
I’ve hit a few things I shouldn’t have, and kept much of my riding to rocky, hilly and tight singletrack. And save for burping at too low pressure – the XC923 wheels haven’t skipped a beat. Next up – a couple months more riding on them.
And the costs? The XC923 Rims are $USD249 each, so it depends what your build choice is, or whether you get rims alone. You can get a custom quote, with shipping, direct from Light Bicycle. Their customer service was super fast and friendly – and best of all their quote for me was highly accurate.
Who has your back?
Light Bicycle have a one year warranty on their rims, with a two year crash replacement warranty. This is the same as some other manufacturers, but shorter than others. Of course, if you have trouble with carbon wheels that you bought from your local dealer – you take them to your local dealer. That won’t be as easy with an item purchased directly. However, as most warranty claims are done via serial numbers and digital photos – for a little more work at your end the result might be the same.
Check back in a couple of months for our full review of the wheels.
Cost: $USD1036 for the wheels, tape and valves
From: Light Bicycle