The Truth About Wide Tyres And Wide Rims On Road Bikes


now if you paid much attention to bike tech at all you will be well aware of the huge push to wider ties and wider rims now you might not be clear as to why there’s this huge push but that’s okay because we’re going to dig in and find out the reason we’ve been thinking about this recently though was because of the arrival of n B’s new and really rather lovely SES 4.5 aar disc wheels the other day now at first glance they are typically mb they’ve got the different rim profiles front and back and they’re laced to Chris King hubs but they’re envies with a difference because these are breaking new ground in a really exciting way for start they have a disc specific rim profile and then they’ve also quite frankly that why this rims I’ve ever seen on a road bike measuring in a 31 and a half mil wide width crucially 25 mil internal rim width as well the design has only been possible following a recent developments in road bike design itself so the fact that they are dis specific means that they can be wide because there’s no restriction on rim width from brake calipers and then again being dis specific you can have much greater tire clearance because again you’re not restricted by those brake calipers so that is why we’ve been thinking about it what about our initial question then why this drive to wider tires and wider rips [Music] [Music] now one of the most intriguing but also significant benefits is actually that wider tires generate less rolling resistance it’s hard to know what we’ve only really just gotten onto this bagg given that rollin existence data has actually been out there for quite some time but nevertheless it is there and a 28 C tire is shown to roll 2 to 3 watts faster on average than its equivalent 25 C tire and that is per wheel and at 40 K now and the difference is even greater on 23 and the reason or at least the theory is that is because of the shape of the tires contact patch and so that as a tire gets wider the contact patch gets shorter and that therefore improves at the rolling resistance now what’s really important to note though is that you need a wide rim as well as a wide tire in order to maximize these benefit because actually the cross-sectional profile of the tire is really important when thinking about that contact patch shape but also the cross-sectional profile is also important to minimize deflection in the tire which is kind of a little bit like that squirming feeling that you get when you pressures are really low because deflection means friction and friction in this case it means increase rolling resistance so you’ll see with this 28 C Schwalbe on this wide entry rim which now actually the time measures up close to 31 you’ll see the cross-sectional profile is really square really well supported and actually well rear that also means it’s more aerodynamic to now in a lab setting using finely tuned equipment it is easy to quantify these results but what is becoming increasingly interesting is actually testing out on the open road spearheaded by bicycle quarterly they pointed out that lab tests miss a crucial aspect of riding and that is vibration and it’s the road buzz that really slows us down and it’s funny isn’t it because when we ride across cobbles or pave it seems clear that the jarring and the vibration is slowing us down we can really feel it but why then when looking at ordinary tarmac did we not draw the same conclusions well unfortunately bicycle quarter lead if and when they tested it out they found that a wider tire with less pressure rolls significantly faster than a harder one when we say less pressure we really mean it I’ve got just 50 psi in these 28 and the reason is because in a lab setting a harder tyre rolls faster because there’s less hysterical loss so that tyre deflection and the friction generated that we just talked about where as out on the open road those losses are more than offset by the gains made a reduction in vibration or what Y School quarterly determing suspension losses what you need to remember though is that you stop letting pressure out your tires when they start squirming because at that point you’re going to be going slower again now I appreciate that reducing rolling resistance isn’t going to be the be-all and end-all for all of us but it seems pretty clear that a fairly major benefit to reducing vibration it’s going to be increased comfort for us Lacey you can run the most comfortable frame in the world but if you’ve got narrow hard tires on it it’s never going to be as comfortable as a stiff racy frame with plush 28c tires on it now that’s not got you thinking that wider tires yet I’m still not finished wider tires give you more grip when cornering now it comes back again to that whole contact patch thing but also a softer tire is more secure on the road now I’ll admit sometimes feel like I’m getting a little bit old I don’t really want to test this one out thoroughly but even at my current speeds I feel more secure leaning in there is one other aspect to wider ties there should be a tangible benefit to all of us and that is puncture resistance because a wider tire means increased air volume which should mean you’re much less likely to pinch flat even at lower pressures and then when you add into the mix that these wheels of designs we run tubeless well simply pretty well insured against flats which you find out [Music] now on comment that we see quite regularly is why if why the ties are so good a pros still running 25 and it’s a good point pros tend to gravitate to whatever is fastest so it must be downsides right well firstly and foremost as I said earlier you do really need a disc brake bike in order to get baptized in gold and so pros obviously can’t use those but then of course there’s the fact that wider tires are slightly heavier these ones are about 20 grams per wheel weightier than their 25 brothers and then there’s also the fact that there is a slight aerodynamic penalty for wider tyres admittedly it’s really small on these because they’ve been designed to accompany wider tires but if you try and fit a wider tire on a rim design for a 23 or 25 the penalties are much bigger and then of course there is tradition the pro peloton could sometimes be described as being like an oil tanker in there it takes them a very long time to change direction we just witness the amount of pros that are still not using Aero bikes despite the obvious advantage to them what tires are probably a little bit like that it’s gonna be interesting though to see where this all ends up I mean how fat are we going to go and who is going to get onboard certainly haven’t seen the data it’s hard to argue with it so I think the future probably looks a little bit better now if you want to see a bit more information about these wheels I’m riding and we’ve got an unboxing video with just these very set just up there but mitad Li you can’t winner anymore so apologies for that or to see the out-and-out Guru behind MV wheels in the wind tunnel click just down there otherwise make sure you subscribe to GCN to do that just click on the globe

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