First Look: IBIS 741 Carbon Rims: The New Wide
Sometimes as I ride my bike, I wonder what the next big advance will be, how can the technology we rely on can get any better! If you had told me ten years ago that I would have a remote on the bars to control the seat height, and no tubes in my wheels, I would have presumed you were one banana short of a bunch. Bike technology has come such a long way, sharing almost nothing in common with the clunky, steep and sketchy bone shakers that we grew up on. Brakes are now incredible, suspension is now so effective that it would not seem out of place on a F1 car, just how can things get any better? However, progress marches on and nestled away in industry offices, coffee fueled engineers ponder the next big advancement, and it looks like we are about to reinvent the wheel!
We had been sent a set of the 27.5″ 741’s, the widest of the new range of rims that Ibis are offering. As I reached in to pull this test set of wheels out of the box, I thought initially that someone had left some tyres on them, they are simply huge. With a 41mm external and 35mm internal width they are significantly bigger than a conventional rim. Wide rims are not new, there have been a number of companies that produce wider than standard rims, but it has been slow to catch on.
Now that ‘carbon maestros’ Ibis have entered the game, will the tired ‘wheel size debate’ now turn its focus onto width? Ibis claim that “A wider rim delivers better sidewall support so you you can run lower pressures in your rubber. Lower pressures do several beneficial things, including increasing the contact patch, which results in better traction. Tires mounted on wider rims don’t burp as easily. Running lower pressures on varied terrain actually reduces rolling resistance. Wider rims are stronger and stiffer. With increased traction comes increased braking control“.
So how can lower tyre pressures equal faster rolling speed? Well the science is pretty simple, back in the old days we were all told that if you want to go faster, pump your tyres up harder. This works just fine for tarmac and super smooth trails, but when the ground is rough or chattery, each bump is like a mini climb, and forward propulsion force is reduced as energy is used to lift the bike and rider upwards. If the tyre is free to conform to the ground a little, this upward force is reduced and the bike can travel faster. So for rough trails what we need is a lower pressure! This is all revolutionary thinking and certainly against conventional wisdom
The increased width of the Ibis 741 wheelset allows you to run 4-6 Psi less in your tyres, while maintaining sidewall support and avoiding burping. According to this new way of thinking, lower pressure equal faster speeds on rough trails so should produce a fast rolling wheelset. The weight of the 41mm rims is also very good too, with each rim weighing in at 475g and building upto 1650g a pair.
The rims also feature ‘hookless bead technology’, with a thick rectangular sidewall where the conventional inverted J hook is normally found. This has allowed Ibis to add a lot more material to the sidewall of the rim, creating a stronger interface that is more resistant to damage. Ibis claim that this is 50-300% stronger than other leading carbon rims on the market when it comes to impact tests. We are keen to see how the hookless rim performs on the trail, and with a busy race schedule planned, we will be putting the impact resistance of these $1299 wheels to the test!
We will be thoroughly testing these rims over the next few months to see how they perform, and challenging them with different tyre profiles and pressures. We will be sure to let you know how they get on!
Words and photos: Trev Worsey
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