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wzzzzzzzzz - I agree. I want the tyre with the best grip that is not unacceptably draggy
If wide soft tyres are faster why is my fatbike so slow?
I want to go faster because it’s a race. So I have aero on three wheels, all of which have narrow rims. So 20c tyres are the best aero match for those wheels. Fortunately it’s on reasonable A roads. For general riding I’m happy with less fast. So 25c is fine the 32c i commuted on today feel like overkill though. Noticeably harder to spin up, even on light wheels
Some of us race. Some of us ride in chain gangs and fast group rides.
Don’t compass make 35mm light tyres? They do two options, normal and light, but not sure of the competitive weight to a normal 25 or 28mm tyre.
The data is already dry there showing the tyre size and the crr and aero differences. As I’ve mentioned earlier and said rather a lot on this forum, Zipp and Enve have published data on tyre sizes, google 105% rule for cycling. All the data is available to read.
Used to run 40mm compass Barlow pass extralite at 42 psi on my tripster (well under 300g I think) and they were bloody fast as shown by times on my fav loops round the roads in Galloway, poorly surfaced and more than not they were chipsealed with chunky gravel. To begin with I thought they were slow on the road due to them making the ride feel so comfortable and relaxed as I was used to getting bounced around on my previous 28mm at 90 psi but after quite a few rides I found I was getting home earlier than usual and my back and shoulders/arms/wrists etc didn’t feel as beat up.
totally unscientific but fat tyres with a light and supple casing to conform to the surface and run at sensible pressures are faster over normal roads, high pressure 23mm tyres belong on a velodrome.
fight !..........
Somafunk, scientifically they are proven to be slower. But it’s not a massive difference, but it is quantifiable slower to use wider tyres on current road bikes.
I’ve provided the evidence in this forum in similar debates on numerous times. Then a month later the same question is asked and always using the Compass / Bicyling weekly advertorial as the benchmark. Rather than look for the 105% rule which is used by Zipp, Enve, Bontrager and Reynolds.
I’ve also ridden compass (panracer made) 35 and I think 38mm tyres. They are really good tyres for winter riding. But I don’t find them as fast in race conditions as my 23mm race tyres. There’s also not always a big difference in grip between 23 and 35mm tyres. That comes down to casing, the panracer /compass tyres in my opinion are the best wide tyre I’ve used in that regard.
People should ride what they want and if a wide tyre makes you think it’s the fastest for your conditions, that’s great. But please read all the different views out there, including those of the people who make wheels and whose job it is to make the fastest race system, not just the views of those people selling wide tyres.
I’d agree that on a specific wheel and in specific conditions a wider tyre will be as fast or even faster than a 23mm tyre. But there are very few wheels or bikes available to take a 30mm external rim, Enve 3.4 AR is the closest that I’m aware of.
Why do you all want to go faster so badly?
tyre choice should come somewhere after skin suit and aero lid which would be a long way behind tri bars 😀
Apart from tri bars are not allowed in a race, chain gang or fast group ride.
And most importantly I can’t get any tri bars to fit my aero bars!
chain gang or fast group ride
LOL the rules the rules
I'll add some anecdotage, since I was thinking of this while riding back home yesterday. My commute is mostly dirt road, and I alternate between two bikes on different days, one of which has 37 mm tyres and the other 31 mm. I realized that I feel a significant difference between how they react to deeper and looser sand and gravel. The thinner-tyred bike feels like it slows down when riding through the softer stuff, which I hypothesized is due to plowing into it, while wider tyre rides on the top and isn't affected as much. So, as said above, what you consider a road has a lot to do in what kind of tyres are faster.
As an another example, not from me, a local ultracyclist experimented with a 90's ATB and some wide, around 50 mm, Compass tyres a year or two back, but came back to 32 mm's because they were faster and comfortable enough for him.
I have ridden a range of tyre width's on the gravel roads I ride on and would agree. I am currently on 23c and they are slower on gravel. Last year I tried 43c and 38c in same tyre model and the 38c was faster overall. The 43c was 100g heavier and teh extra width didn't seem to make any difference.
However both of those sizes of tyres made the bike just feel less responsive so I went back to 28c.
For me tyres are not just about speed but how they make the bike feel. I like 23c on road but they are not as nice off road. The difficulty for me is that pretty much every ride I do is 50% road and 50% gravel.
Klunk, if you race road or crits with a team then you would ride in a fast group ride or a chain gang. Another name for it is training.
When I’m pootling along I’m more than happy to use 32mm or wider tyres.
The question keeps getting asked about the lack of scientific evidence around tyre width, but it tends to be from guys who commute in wider tyres and want a level of justification for their purchase. The evidence is there, it’s real. But it’s like talking to flat earthers.
If my winter bike could take 35mm tyres
I’d run a set of compass tyres on them. But I’d accept that scientifically I wasn’t on the optimal tyre size.
If people feel safer and faster in wide tyres that’s great, but it doesn’t mean the science and the Manufacturers are wrong.
Another name for it is training.
so they are allowed then ?
Tri bars? No. Not for chain gangs. But that’s because they would be deemed unsafe at that intensity.
We have between 6 and 10 guys riding at max effort centimetres away from each other. Tri bars wouldn’t be safe. Different discussion though.
I already have the skin suit helmet and aero front end tribars 🙂 . Now down to tyre choice. I had the choice of 23c GP5000s or 20c GP4000s because Continental have not produced their newest Uber tyre in the narrowest width. The watts saving for the new ones, which are very good, would be less than the aero savings from a properly fitting tyre. And all three wheels are right out there in the wind (it’s a delta upright tricycle). Also for the two rear wheels this will help a little with load and hence comfort and I can run them a little lower than 120psi.
Now for training I run 23c on different wheels. It’s more comfortable. But not faster. I race my two wheelers on 23c front and 25c rear because the back tyre is shielded by the seat tube. Front is out in the wind.
There have been aero tests of width vs power (aero coach published one). And it’s a real effect. In a TT you need every watt you can find. In a road race you still need them even when drafting.
From my commute times going from 28c gp4000 on a carbon road bike were about 3 minutes fast over 10miles than 40c wtb nano on a alloy gravel bike. The gravel bike winning on comfort road holding. The lack of buzz on poor road surfaced is more than worth losing 3 minutes. Even sold the road bike as I just don’t use it anymore.
Correct me if I'm wrong @w00dster but I thought the data from Zipp, Enve etc was only for lab tests.
Not that there is anything wrong with lab tests. They are a great way to isolate a single factor and dramatically reduce the variance allowing you to tease out tiny differences in that one factor. The problems comes when you try to extrapolate to a real world situation and have to make assumptions about all the other factors, especially if those assumptions have not been validated.
I'm happy to accept that the evidence shows that hysteresis and aerodynamic losses are greater in a larger tyre. They are also (like for like) heavier. But they have an advantage in reducing suspension losses and these seem to be very poorly understood. So, people look at lab data, which shows hysteresis or aerodynamic loses are higher and conclude that wider is slower (i.e. ignore the suspension effect that "may" offset these losses). Or they say things like "narrower tyres are better on smooth roads" without providing evidence. Yes a smooth road is smoother than a rough one, but it's not perfectly smooth. Does that matter? I don't know.
The results I've seen are enough to convince me (and most of the pro peleton by the sound of it) that 25 is faster than 23 pretty much everywhere. I'm also convinced that 28 is probably better than 25 at the sort of speeds I ride at and on the sort of roads I ride on. But I'm left wondering what happens above that. Maybe the negative effects (hysteresis, aerodynamics, weight) outweigh any suspension benefits on all but the roughest of surfaces. But I'd like to see the proof.
Why do you all want to go faster so badly?
It's a good question. I ride on my own, so why do I care about speed? Off road I don't. I choose to use tyres that provide plenty of grip and security in exchange for speed as I'm just out there to enjoy the environment and going faster really doesn't improve things for me. It's why I've no interest in ebikes, but that's a different thread.
So the question, for me, is why ride on the road? I prefer riding in beautiful places, with peace and quiet, away from the noise and annoyance of cars (and people for that matter). I can get all that off road. But one thing I get from road riding that I can't get off road is that feeling of effortless speed. I quite like the idea of tyres (or even a bike) that opens up options to take rougher tracks. But take away that effortless speed any I've removed the main reason why I would ride a road (or gravel/adventure) bike in the first place.
If wide soft tyres are faster why is my fatbike so slow?
"all other things being equal". Your fatbike tyres are running very low pressures, probably of not that light construction, and the overall weight is much higher.
The corollary to wanting to go faster (with acceptable levels of grip) is wanting to put less effort in for the same speed and grip, or get more grip for the same speed and effort (and durability/reliability of course). I don't know anybody that doesn't want this tradeoff to be better, no matter what they say.
I choose to use tyres that provide plenty of grip and security in exchange for speed as I’m just out there to enjoy the environment and going faster really doesn’t improve things for me. It’s why I’ve no interest in ebikes, but that’s a different thread.
I challenge you to go out and buy a set of dual ply supertacky Swamp Things (NOS somewhere perhaps - I'm sure the current version will be a bit faster rolling) and still feel this way. You won't better the grip on a rooty rocky muddy ride, but you will want to roll faster unless you have an uplift and 100% steep descents. And it's not just the weight, it's like riding with the brakes on.
Hi Roverpig,
I'm not disagreeing that 25 or 28mm could be faster (or as fast as a 23mm tyre). But it needs the correct rims / frames to make that work. With regards to riding conditions, thats very changeable, so my information is based on tests showing the actual fastest, not the fastest for your personal ride.
Real world tests have been done and the Hambini blog is worth a read, 23mm still comes out on top. But the margins we are talking are incredibly small. Hambini has completed a mix of lab and real world testing, but the focus has been on the wheel rather than tyre - after all they have already concluded what is the fastest tyre/rim combination. An extract "This guidance is uniform across the board. It is vitally important to install tyres that are slightly narrower or inline with the brake track of the wheel rim. A ballooning tyre will impact the drag significantly.
There has been a trend towards wider tyres on bikes of late. From an aerodynamic perspective, the width of the rear tyre has little effect but the width of the front tyre has much more impact and therefore a 23mm front tyre is recommended irrespective of whether the wheel was designed for 25mm tyres. At speeds above 30km/h, it is more beneficial to have 23mm tyres than 25mm front tyres for aerodynamic benefit."
https://www.hambini.com/blog/post/bicycle-wheel-aerodynamics-which-one-is-fastest/
Its worth saying incase it gets missed in the long texts. Read about the 105% rule, this is what wheel manufacturers build to and reflects what Hambini is stating. Really worth a read. The point I try to make is that the accounts made by Bicylcing Weekly and Compass that fatter tyres are faster is incorrect and the science points away from that.
For my closed circuit crit racing, 23 front and 25 back is without doubt the fastest combination for my wheel profile, the wheel and the bike are designed to work specifically for that combination. But, that is completely different than other people's riding. With my current rims I personally wouldn't race on anything above 25mm, that includes open roads where the tarmac isn't always great.
The testing has been done to show that 28CRR is pretty much the same as 25, above 28 and CRR stays pretty similar but drag increases. Its all marginal, hence why I ride with 32mm for winter rides. Once wider rims and disc brakes become the norm, then this will change the tyre / rim design. Hunt have a wider rim as do Enve, I'd happily race wider tyres with those rims. (As the pro's ride with wider tyres with the rim with the wider brake track - but this is also only for specific races)
Site I've previously linked to that is well worth a read.
https://blog.silca.cc/part-5-tire-pressure-and-aerodynamics
The results I’ve seen are enough to convince me (and most of the pro peleton by the sound of it) that 25 is faster than 23 pretty much everywhere.
You will find that there are no pros racing TTs on 25c tyres. Most TT wheels are now optimised for 23c clinchers or 22c tubulars. HED have made their iconic Hed3 rim wider due to the availability of narrow tyres diminishing (19-20c) and some percieved comfort benefits. But the original 17mm internal diameter wheel is faster when run with the correct tyre. And my it is fast! I run 23c on my rear disc wheel, which is a wider Hed wheel. But rear is not really an issue for two wheelers due to the seat tube.
On my best bike, I run 25c GP5000 front and back with latex tubes on wide 60mm carbon rims. It's a great choice for general roads, comfortable yet fast. For road racing I run 23/25c Corsas on older Hed Jet6/9 rims, but will eventually switch to GP5000s as I like them that much.
There's not a huge amount in it, but I can'r see a switch to anything wider any day soon. The 32c Schwalbe G One Speeds are a nice tyre, and I run them tubeless, but they are not in the same class 😉
25c is the new 28c as far as I can see.
28mm works for some
What is "real world"?
https://www.conti-tyres.co.uk/latest-news/165-wider-tyres-go-faster
https://www.cyclist.co.uk/in-depth/726/are-wider-tyres-really-faster
https://www.businessinsider.com/tour-de-france-wider-tires-lower-pressure-faster-2018-7?r=US&IR=T
Maybe different tyres and different tyre pressures suit different riders
https://www.youtube.com/watch?v=E3C5RzQrTvw
If wide soft tyres are faster why is my fatbike so slow?
Ohhh, I dunno.
I did a local hillclimb on my on-one and didnt come last beating a few road bikes (at least one ridden by someone i didnt think id beat even on a propper bike) despite having a nightmare with pacing and taking the steepest bit far too easily thinking there was more to go.
Its still slower though.
Well it’s going to take me a while to get through that lot (I’m still working through the homework @w00dster set me 😀) but thanks.
GCN video is summarised by 28mm tyres or slightly wider on the wide Enve rims is faster than a 25mm tyre. I’d agree with that, in those rims on that bike.
Most rims though, nope. Simon does say that in the video (approx 6:50 in).
There’s no science or details on the tests carried out, just refers to the Compass tests.
The cyclist test, while interesting isn’t really a good test, that’s a roll down test on an 18 second test. Using a rider doing 30 attempts. Room for error seems to be high.
Extracts from the continental data “ Tyre giant Continental claims a 23mm tyre at 120psi, a 25mm tyre at 90psi and a 28mm tyre at 80psi all have the same rolling resistance.
Wider tyres may provide less rolling resistance, but they can increase the amount of aerodynamic drag, cancelling out any gains you may have made. This is especially true if you have narrow rims, as the larger tyre will bulge out more. The best way to get the most out of your wider tyres is by having wider rims to match. This creates a more rounded and aerodynamic profile, helping to get the best of both worlds; lowering rolling resistance and aerodynamic drag.”
The best way to get the most out of your wider tyres is by having wider rims to match. This creates a more rounded and aerodynamic profile, helping to get the best of both worlds; lowering rolling resistance and aerodynamic drag.”
Whilst true, a wider rim will minimise drag for a wider tyre. It doesn't get you round the simple fact that the A in CdA is area, and a 28mm wide wheel is 40% wider than a 20mm wheel so even if both were optimised for their tyres its still a little over 40% more drag.
When they talk about the aerodynamics of the tyre being important, I wonder just how significant that figure really is.
There are fork legs, spokes. cyclists legs, cranks and frame tubes also creating drag in that part of the frontal area.
Is the magnitude of the aerodynamic gains a significant figure compared to those?
And does it matter to anyone who isn't capable of TdF type performance?
Epicyclo, they have quantified the aerodynamic loss of the different tyre size, all bikes have spokes and forks so that’s a consistent figure.
Agree that it may not matter to some. For some people having a 32mm tyre losing a small number of watts and being heavier than 25mm tyre won’t matter.
You don’t need tdf levels of performance though. People on this forum will be fast riders, solo and in group rides/races and will want their most performant set up as possible. For me doing a crit on closed roads, tends to be decent enough road surface and comfort for 1 hour 10 mins isn’t an issue, I want to have the fastest possible wheel and tyre set up.
If I was riding on broken roads, lumpy up and down sections for a long race, I’d probably be happy on wide rims and 28 or 30mm tyres. (Not 50mm though)
But with the existing rims I have, 23mm front and 25mm rear is proven to be the fastest combination. (Reynolds Strike, 62mm depth, 25mm outer and 17mm inner)
It's an interesting discussion. My questions are a) given that a bike is generally quoted at about .85 - .90 drag will the change from a given Tyre size, assuming appropriate wheel size, be enough difference to detect, relative to total drag.
B) given that drag is the square of speed, will people outside of top flight TT go fast enough to worry about Tyre drag?
Some excellent articles to read there, thanks!
I've recently gone from race style 23c on a road bike to 35 rear slick, 42 front gravel tread on a cross bike for my commute. There's a bit of a speed difference on smooth flat road, but surprisingly little most of the time... And it opens up lots of interesting route choices.
One thing no-one seems to have noted is the perception of gearing for bigger tyres. You're increasing the driven wheel diameter, so the effective gear increases too. Means that it can feel harder to push the same ratio on bigger tyres, giving the impression of more drag.