Since trucks are probably the most common vehicle to place much larger tires on.. Here’s a few basic numbers in your comparison.
My F250 weighs around 6750 lbs according to google. My tires (37x12.5) weigh 75lbs each. The tires are about 4.4% of the vehicle weight. In comparison, an average gravel rider may weigh 170lbs, + a 20 lbs bike/gear, with tires weighing around 2 lbs. This puts the tires being at about 1% of the overall weight.
My truck tires also raise the truck up 1” over the stock height. In turn, they ride significantly more smoothly than the stock tires (37’s on 17” rims vs 35’s on 18” rims), and they are less prone to flats. If I was in an offroad race, I’d pick my 37’s 10x out of 10, because if I get a flat because I chose a tire with less sidewall/less aggressive tread, changing that tire would negate all gains from the slightly lighter weight/less rotational mass of the smaller tire.
Raising my truck 2.5” in front probably had more of an impact on mpg than going from 35’s than 37’s, because at 60-70 mph, aero plays a pretty huge factor.. Similar that if I drive 80 my mpg might be 14-15, while if I drive 50, they’ll be 20 mpg.
In the context, lower mpg would mean reduced mpg. I.e. maybe a vehicle that was 20 mpg on stock tires, moved to larger tires and was 19 mpg at the same speed/conditions.
Give me a break, you don’t know what lower mpg means? Again, "When you accelerate, this inertia can lead to slower speed gains and increased fuel consumption.”
Increased fuel consumption to go the same speed. As the motor for my bike, I’m worried about things that cause increased fuel consumption, or work, to maintain the same speed. That’s all. I get it that you are saying those losses are more than made up for in the rolling resistance and/or aero gains. I’m not arguing against, I’m just wondering if we have proof either way to get to the right answer eventually. People have been spending a lot of money historically to make their wheels lighter on bikes so it’s just a little jarring that the thing we always said was the first thing to buy for a new bike now doesn’t matter enough to care about. All that said, I have an aero road bike that weighs more than my old climbing road bike and yet, is definitely faster. So I’m open to it. Just ordered the new schwalbe 50’s to give them a try on the gravel bike.
Well, attitude aside, I’ll concede that I should have used the word “quantify” and not “define” in regards to “lower”. Sure, MPG may be “lower” but what does that mean? .1 MPG is “lower” but that doesn’t mean it is meaningful. And, in your example, you are only focusing on one end of the overall equation.
Which brings us back to the key point - the increased energy expenditure of accelerating the larger / heavier tires are offset by the overall gains from other areas.
In the interest of quantifying, do we have data that shows that the gains for sure outweigh the losses? That is the question. It’s easy to say it, but can we demonstrate it somehow outside of…Dylan said it…or Keegan ran X tires one time?
It’s not a “for sure” type of thing. Tire choice is still going to be based around the course but generally the trend is that the fastest XC tires are going to more than make up for their increased aero drag and rolling resistance through improved suspension. In many cases the rolling resistance is lower due to how the different types of tires are constructed.
Torsten Frank and John Karrasch have both provided data, and were/are currently posting in this thread. There is additional data earlier in the thread.
The car analogy does not work because it assumes everything else is held constant.
The marginal advantage with XC tires is that they are currently underbuilt compared to gravel tires. So they have (perhaps “had”) lower rolling resistance than the average gravel racing tire while also providing significant additional suspension, which reduces the largest factor in total rolling resistance on gravel.
The car analogy can only be made equivalent by making it more quantifiable, and unanswerable - Your put new tires on your car that are 20% heavier heavier but the CRR is reduced by 30%. Does your gas mileage increase or decrease?
For bicycles, we have a good idea of what happens when tire weight is increased by ~35%, the rolling resistance is similar, and the suspension losses decrease by 20%+ - speed generally increases.
The fastest gravel tires are most likely faster than the fastest XC tires, on pavement or very smooth dirt where suspension losses are very small. As suspension losses increase XC tires will become relatively faster, gravel tires will become slower. For many courses the suspension losses are great enough to offset the weight and rolling resistance (on pavement) disadvantages of XC tires.
Actually totally depends on speed. I’ve got the mtb tires closing the CRR gap on even hard packed super easy gravel track testing. That’s the “cat 1” gravel I’ve got in my posts. Really surprised me!
Is this a normal super ground thunderburt? The snakeskin description was throwing me off since that isn’t mentioned on the schwalbe website page for thunderburts.
And Keegan runs maxis tires which are not nearly the fastest in terms of rolling resistance in gravel or MTB…
When athletes have sponsors, it’s sometimes overlooked as to whether they are using certain gear because it’s the best, or because they get paid the most to run it..
If you’re talking specifically as to whether or not the gains of a wider, more supple, tire with a lower rolling resistance are larger than the losses due to the increased weight, then there isn’t really anything you need to know other than the physics of rotational mass, which have been “debunked” dozens of times in regards to cycling specifically. Even something like a 200g per tire increase is way more than offset on anything other than if you were doing 15/15sec start stop efforts up a 10% gradient. We’re talking like single digit wattage increase of extra effort/work to get a pair of 200g heavier tires up to 20mph from 5mph(aka, like 1% extra).
I scanned the recent replies and no one is saying weight doesn’t matter.
We are all saying variations of this:
…the gains of a wider, more supple, tire with a lower rolling resistance are larger than the losses due to the increased weight…
Which is what the current models, testing, and tire construction types support.
Weight matters, but if saving 400g rotating mass has a potential to save 1%+ of power required, and improved rolling resistance and suspension has a potential to save 5%+ power required, then there isn’t much argument to be support narrower, lighter tires.
The lightest, fastest, practical Schwalbe gravel tire at BRR is the G One RS SR 40mm at 473g
The Race King is 586 and the Thunder Burt is 611/680
So weight savings of 226-414g with the narrower tires.
This sort of begs the question, why not run the G One RS SR in 35mm? It weighs 50g less for the pair. Or even better, why not run a road tire? The Corsa Speed 28mm would save 466g…
If you are moving to a carbon rim of similar profile / depth, then yes….thee is limited benefit to moving to a carbon wheel.
But a move to a carbon wheel almost always includes moving to a more aerodynamic profile….sl the. The aero gains ar significant combined with the weight savings……win-win.