What Are Hookless Bicycle Rims?

If you've kept up with the latest wheel releases, then you've probably noticed one thing

Hookless rims. They seem to be everywhere, but what are they? Well, this piece of technology is relatively new to the road and gravel market

And what benefits does it bestow to the user, and what potential negatives are there

Well, today, and in this video, I'm going to tell you seven things that you absolutely have to know about hookless rims

I quickly need to step back in time. You see, in 1970, Mavic released its Module E rim

a rim that was certifiably a game-changer in the world of cycling

You see, before that rim existed, the only choice for racing was tubular tyres

wherein you glue a tub, a tubular tyre, onto a rim. For every other type of cycling, there was something called wire-on tyres

but these tended to be heavy and quite slow. The difference with the module E was it incorporated a hook, which allowed it to capture a lighter foldable beaded type of tyre and prevented it from blowing off at high pressures

Ever since then, that has been the most commonly used form of rim for bicycles

But now we're starting to see more and more hookless rims. put simply and as the name suggests a hookless rim is a rim without the hook that would usually

capture the bead of a tire if you look at a profile you'll see that it lacks a hook at the

top of the side walls of the rim and instead is completely vertical now this means a couple of

things that are quite important that you need to know the first one is that you cannot use clincher

tires. This is a tubeless only setup. That's not to say that you can't run tubes. For example

if you had a catastrophic puncture, you absolutely could, but you could not change the tires to a

clincher version. Even more confusingly, hookless rims aren't actually compatible with all tubeless

tires on the market. And I'll come into that a little bit more later on in this video

Cycling is lagging and not leading when it comes to hookless rims

In fact, it has taken from about the 1970s until now for cycling

especially road cycling, to catch up with other pneumatic forms of transport

Mountain bikes have used hookless rims for a little while now, but road cycling has sorely lagged behind

However, that does seem to be changing, and although they're hardly universal yet

there are a lot of notable brands putting quite a lot of time and energy

into developing hookless rims for the road and gravel market. These include Envy, Zip, Cadex, the sister company to Giant

and Giant themselves, all of whom are putting money into hookless rims

And today I using Giant SLR1 wheel to perfectly demonstrate exactly what hookless rims are and what all of these brands are espousing when they say it bestows a lot of benefits to the user

I'll start by explaining exactly what the hook is and it's pretty self-explanatory. The hook

is part of the rim profile that captures the tyre's bead and prevents it from blowing off

when inflated. On hooked rims if you feel the side of the rims there you'll naturally feel a little

lip at the top and that is exactly what we're referring to when we talk about a hook. Meanwhile

on these hookless rims you'll notice if you can see up close that the rim profile is completely

straight with vertical sides and that's where they're lacking the hook. Now in the early days

of tubeless mountain biking setup it wasn't uncommon for riders to experience something

called burping. Burping was the sudden and unexpected loss of pressure between the tyre

and the rim wall. Now this could happen for numerous reasons. It might be that the tyre

bead wasn't stiff enough or that the pairing between the tyre and the rim wasn't quite right

and air was able to escape. Either way imagining burping happening on a road bike is absolutely

terrifying. Now proponents of hookless rims actually say it's a much safer way to have a

tubeless setup and that might seem strange because you're literally removing the hook

the thing that was designed for years to keep tyres in place. However Zip have done a lot of

research into this and have found that the pressure required to blow a tyre off a hooked rim

and a hookless rim is actually very similar. As another example Envy say that by removing the hook

from hookless rims, brands can actually make sure that the bead seat diameter of the rim

is accurate and consistent the whole way around, allowing for a better pairing between the tyre

and the rim. Now this leads neatly on to another aspect that brands are keen to push when it comes

to hookless rims, that is superior manufacturing. Proponents of hookless rims are keen to talk about

their simpler but superior manufacturing process. Zip for example told us that hookless rims allow

better carbon compaction, better resin distribution throughout the rim, more accurate bead seat

diameters and ultimately less scrap and less waste. To help demonstrate this point I'm going to talk

a little bit about rim manufacturing but I'll keep it brief because it can be a bit complicated

But in short, with hooked rims, brands use a silicone mandrel to mould the tyre bed cavity

Now that silicone mandrel is quite soft and can only be used once and then it needs to be thrown away

However, with hookless rims, brands can use a steel mandrel to mould that tyre bed cavity

and they can get many more uses out of that because it's much harder. That's not the only benefit either

A steel mandrel allows them to create more accurate and more consistent tyre bed diameters allowing for a better pairing between the tyre and the rim The other manufacturing benefit of hookless rims is that you can get a better distribution of resin in the rim

Now, this not only allows you to create a better interface between the tyre and the rim

which is obviously incredibly important, it also crucially allows you to drop the weight of the wheel

However, that's not the only thing you drop with hookless rims. brands are also keen to state that they are ultimately cheaper for the consumer because of

these more efficient manufacturing processes. Now Zip are very keen to state that their new 303

firecress wheels are 300 grams lighter than the old model because they have moved to a hookless

design and also they are 30% cheaper than those old models as well. Of course inevitably there

will be those that say the drive behind hookless isn't because of performance reasons for the user

but actually because of cheaper manufacturing costs for the brands. And they might well be right

It's still a little early to tell, but it will be really interesting to see in the future

as hookless rims become more available and more common on the cycling market

where the prices really do go down for the end user. Until very recently, if you'd asked me

what the widest internal rim widths I'd expect to see on a wheel, I'd have told you 21 mil. That was usual for both Zip, Envy, Hunt. All of these wheel manufacturers

had internal rim widths that were that wide. However, with their latest releases, both Zip

and Envy have wheels which have internal rim widths of 23 and 25 millimeters. But why have

they done this? Well, it all comes down to the shape of the tire. You see, on a hookless rim

the tire side will sit further apart because they're not being pulled inward by the hook

If previously you'd put a wide tyre on a rim with a narrow internal rim width, you'd have got a bulbous shape to your tyre and it would have looked like a mushroom coming off the top of the rim

Now that interface between tyre and the wheel has long been the subject of study for aerodynamicists who all say that a flush interface

so one that sits neatly the rim into the tyre and not a bulbous shape, is much more aerodynamic

What's more, because those sidewalls are further apart, you're able to run your tyres at lower pressures

This not only creates a more comfortable bike ride, but also has been proven to make the bike faster

Zips say that on a smooth asphalt road, a wider tyre can expect to save between 3 to 5 watts, up to 40 watts on a rougher surface

Now, of course, not all riders are going to want to go for wider tyres

but if you look at the recent trend of GC bikes and the sort of top-end race bikes on the world tour

you'll definitely see that there is a trend towards wider tyres on fast bikes

The reason you might be limited in tyres for your hookless rims is ultimately due to the lack of standards around them Basically the rate of change on hookless rims and tubeless tyres have gone so quickly that the two governing bodies

the ETRTO, that's the European one, and the ISO, the international one, are yet to be able to sign

it off. They have fears that high pressures might blow the tyre off the rim and it's not something

they've experienced yet because mountain biking, where hookless rims have been used the most, tend

to run their pressures much much lower than we would on the road. However, with road and gravel

companies using that technology from mountain biking, they've been pushing the rate of change

in hookless rims much faster than those two governing bodies can keep up. For this reason

it has been left to rim and tyre companies to work out which tyres are compatible with which

rims and most of this legwork is being done by wheel manufacturers. For example, Giant told us

that they're working really closely with tyre brands in their testing protocols

which involves inflating a tyre to 1.5 the maximum pressure standards to see if it will blow off the rim

Now, if you look at Zip, Envy and Giant's websites, all of them have lists of tyres which are compatible with their rims

but some of them are smaller than others. For example, Zip only lists five brands that it feels are compatible with its rims

whereas Envy and Giant list a little more. It's all a little bit murky and quite confusing at the moment and not unlike the Wild West really

But as the pace of change increases and the steady march of technology carries on

expect to see tyre brands and rim manufacturers working together to create more compatible products

Early adopters of the tubeless setup will no doubt welcome hookless rims

and the better interface between tyres and rims that it offers, and therefore a more secure setup

However, as we know from our comments section, not everybody wants to set up their tyres tubeless

and there will be those that are saying there's no demand for hookless rims, and that it's not necessary in the road market

Now, it does feel important to say that at the time of filming, neither Continental nor Vittoria

two of the biggest tyre manufacturers in the world, say that their tyres are compatible with hookless rims

I'd hazard that it will take a couple more of the big name tyre brands to get involved and ultimately for ETRTO and ISO to get involved and to set some standards

But the upshot for the end user could be better value and lighter wheels

So there you go. Seven things that you have to know about hookless rims

A new technology for the road and gravel market, but one that seems to be advancing at quite a pace

if you have any questions about these new type of rims then please do leave them in the comment section below and i'll do my best to answer them and if you have found this video

helpful do give us a thumbs up and subscribe to the channel it really does help us out now i'll

be back soon with some more great tech content and i'll see you then