What Are Hookless Bicycle Rims?
7 Things You Need To Know.
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00:00If you've kept up with the latest wheel releases and you've probably noticed one
00:04thing. Hookless rims. They seem to be everywhere but what are they? Well this
00:10piece of technology is relatively new to the road and gravel market and what
00:14benefits does it bestow to the user and what potential negatives are there? Well
00:18today and in this video I'm going to tell you seven things that you
00:22absolutely have to know about hookless rims. I quickly need to step back in time.
00:33You see in 1970 Mavic released its module E rim. A rim that was certifiably
00:40a game-changer in the world of cycling. You see before that rim existed the only
00:46choice for racing was tubular tires. Wherein you glue a tub, a tubular tire,
00:51onto a rim. For every user type of cycling there was something called wire
00:55on tires but these tended to be heavy and quite slow. The difference with the
01:00module E was it incorporated a hook which allowed it to capture a lighter
01:04foldable beaded type of tire and prevented it from blowing off at high
01:09pressures. Ever since then that has been the most commonly used form of rim for
01:14bicycles but now we're starting to see more and more hookless rims.
01:24Put simply and as the name suggests a hookless rim is a rim without the hook
01:30that would usually capture the bead of a tire. If you look at a profile you'll see
01:35that it lacks a hook at the top of the sidewalls of the rim and instead is
01:39completely vertical. Now this means a couple of things that are quite
01:43important that you need to know. The first one is that you cannot use clincher
01:48tires. This is a tubeless only setup. That's not to say that you can't run
01:52tubes for example if you had a catastrophic puncture you absolutely
01:56could but you could not change the tires to a clincher version. Even more
02:00confusingly hookless rims aren't actually compatible with all tubeless
02:05tires on the market and I'll come into that a little bit more later on in this
02:09video.
02:14Cycling is lagging and not leading when it comes to hookless rims. In fact it has
02:21taken from about the 1970s until now for cycling, especially road cycling, to catch
02:28up with other pneumatic forms of transport. Mountain bikes have used
02:31hookless rims for a little while now but road cycling has sorely lagged behind.
02:36However that does seem to be changing and although they're hardly universal
02:41yet there are a lot of notable brands putting quite a lot of time and energy
02:44into developing hookless rims for the road and gravel market. These include MV,
02:50Zipp, Kadex, the sister company to Giant and Giant themselves all of whom are
02:55putting money into hookless rims and today I'm using Giants SLR1 wheel to
03:00perfectly demonstrate exactly what hookless rims are and what all of these
03:03brands are espousing when they say it bestows a lot of benefits to the user.
03:11I'll start by explaining exactly what the hook is and it's pretty
03:18self-explanatory. The hook is part of the rim profile that captures the tyres bead
03:23and prevents it from blowing off when inflated. On hooked rims if you feel the
03:30side of the rims there you'll naturally feel a little lip at the top and that is
03:34exactly what we're referring to when we talk about a hook. Meanwhile on these
03:38hookless rims you'll notice if you can see up close that the rim profile is
03:44completely straight with vertical sides and that's where they're lacking the
03:48hook. Now in the early days of tubeless mountain biking setup it wasn't uncommon
03:54for riders to experience something called burping. Burping was the sudden
03:59and unexpected loss of pressure between the tyre and the rim wall. Now this could
04:05happen for numerous reasons it might be that the tyre bead wasn't stiff enough
04:08or that the pairing between the tyre and the rim wasn't quite right and air
04:12was able to escape. Either way imagining burping happening on a road bike is
04:17absolutely terrifying. Now proponents of hookless rims actually say it's a much
04:24safer way to have a tubeless setup and that might seem strange because you're
04:28literally removing the hook the thing that was designed for years to keep
04:32tyres in place. However Zipp have done a lot of research into this and have found
04:37that the pressure required to blow a tyre off a hooked rim and a hookless
04:41rim is actually very similar. As another example Enve say that by removing the
04:47hook from hookless rims brands can actually make sure that the bead seat
04:50diameter of the rim is accurate and consistent the whole way around allowing
04:55for a better pairing between the tyre and the rim. Now this leads neatly on to
04:59another aspect that brands are keen to push when it comes to hookless rims that
05:03is superior manufacturing.
05:12Proponents of hookless rims are keen to talk about their simpler but superior
05:16manufacturing process. Zipp for example told us that hookless rims allow better
05:20carbon compaction, better resin distribution throughout the rim, more
05:24accurate bead seat diameters and ultimately less scrap and less waste. To
05:31help demonstrate this point I'm going to talk a little bit about rim
05:34manufacturing but I'll keep it brief because it can be a bit complicated. But
05:39in short with hooked rims brands use a silicon mandrel to mold the tyre bed
05:44cavity. Now that silicon mandrel is quite soft and can only be used once and then
05:50it needs to be thrown away. However with hookless rims brands can use a steel
05:55mandrel to mold that tyre bed cavity and they can get many more uses out of that
06:00because it's much harder. That's not the only benefit either. A steel mandrel allows
06:04them to create more accurate and more consistent tyre bed diameters allowing
06:09for a better pairing between the tyre and the rim. The other manufacturing
06:14benefit of hookless rims is that you can get a better distribution of resin in
06:18the rim. Now this not only allows you to create a better interface between the
06:22tyre and the rim which is obviously incredibly important it also crucially
06:26allows you to drop the weight of the wheel. However that's not the only thing
06:30you drop with hookless rims. Brands are also keen to state that they are
06:34ultimately cheaper for the consumer because of these more efficient
06:38manufacturing processes. Now Zipp are very keen to state that their new 303
06:42Firecrest wheels are 300 grams lighter than the old model because they have
06:47moved to a hookless design and also they are 30% cheaper than those old models as
06:53well. Of course inevitably there will be those that say the drive behind hookless
06:59isn't because of performance reasons for the user but actually because of cheaper
07:03manufacturing costs for the brands and they might well be right. It's still a
07:06little early to tell but it will be really interesting to see in the future
07:11as hookless rims become more available and more common on the cycling market
07:16where the prices really do go down for the end-user.
07:25Until very recently if you'd asked me what the widest internal rim widths I'd
07:29expect to see on a wheel I'd have told you 21mm. That was usual for both Zipp, MV,
07:34Hunt, all of these wheel manufacturers had internal rim widths that were that
07:38wide. However with their latest releases both Zipp and MV have wheels which have
07:43internal rim widths of 23 and 25mm. But why have they done this?
07:49Well it all comes down to the shape of the tyre. You see on a hookless rim the
07:54tyre side will sit further apart because they're not being pulled inward by the
07:58hook. If previously you'd put a wide tyre on a rim with a narrow internal rim width
08:03you'd have got a bulbous shape to your tyre and it would have looked like a
08:05mushroom coming off the top of the rim. Now that interface between tyre and the
08:10wheel has long been the subject of study for aerodynamicists who all say
08:15that a flush interface so one that sits neatly the rim into the tyre and not a
08:20bulbous shape is much more aerodynamic. What's more because those side walls are
08:25further apart you're able to run your tyres at lower pressures. This not only
08:30creates a more comfortable bike ride but also has been proven to make the bike
08:34faster. Zipp say that on a smooth asphalt road a wider tyre can expect to save
08:40between 3 to 5 watts up to 40 watts on a rougher surface. Now of course not all
08:46riders are going to want to go for wider tyres but if you look at the recent
08:50trend of GC bikes and the sort of top-end race bikes on the World Tour
08:54you'll definitely see that there is a trend towards wider tyres on fast bikes.
09:04The reason you might be limited in tyres for your hookless rims is ultimately due
09:09to the lack of standards around them. Basically the rate of change on hookless
09:15rims and tubeless tyres have gone so quickly that the two governing bodies
09:19the ETRTO that's the European one and the ISO the international one are yet to
09:24be able to sign it off. They have fears that high pressures might blow the tyre
09:29off the rim and it's not something they've experienced yet because
09:32mountain biking where hookless rims have been used the most tend to run their
09:36pressures much much lower than we would on the road. However with road and gravel
09:41companies using that technology from mountain biking they've been pushing the
09:45rate of change in hookless rims much faster than those two governing bodies
09:50can keep up. For this reason it has been left to rim and tyre companies to work
09:55out which tyres are compatible with which rims and most of this legwork is
09:59being done by wheel manufacturers. For example Giant told us that they're
10:04working really closely with tyre brands in their testing protocols which
10:08involves inflating a tyre to 1.5 the maximum pressure standards to see if it
10:13will blow off the rim. Now if you look at Zipp, Enve and Giant's websites all of
10:18them have lists of tyres which are compatible with their rims but some of
10:22them are smaller than others. For example Zipp only lists five brands that it
10:26feels are compatible with its rims whereas Enve and Giant list a little
10:30more. It's all a little bit murky and quite confusing at the moment and not
10:35unlike the Wild West really but as the pace of change increases and the steady
10:40march of technology carries on expect to see tyre brands and rim manufacturers
10:45working together to create more compatible products.
10:54Early adopters of the tubeless setup will no doubt welcome hookless rims and
10:59a better interface between tyres and rims that it offers and therefore a more
11:03secure setup. However as we know from our comment section not everybody wants to
11:09set up their tyres tubeless and there will be those that are saying there's no
11:13demand for hookless rims and that it's not necessary in the road market. Now it
11:18does feel important to say that at the time of filming neither Continental nor
11:21Vittoria, two of the biggest tyre manufacturers in the world, say that
11:26their tyres are compatible with hookless rims. I'd hazard that it will take a
11:30couple more of the big-name tyre brands to get involved and ultimately for ETRTO
11:35and ISO to get involved and to set some standards but the upshot for the end
11:40user could be better value and lighter wheels. So there you go seven things that
11:46you have to know about hookless rims a new technology for the road and gravel
11:51market but one that seems to be advancing at quite a pace. If you have
11:56any questions about these new type of rims and please do leave them in the
11:59comment section below and I'll do my best to answer them and if you have
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12:06it really does help us out. Now I'll be back soon with some more great tech
12:11content and I'll see you then.