Polaris OBark

My Soma Saga disc frame can accommodate 700C x 55mm tires, so I decided to put some on, specifically, Rene Herse Endurance Plus Antelope Hills.

I set them up tubeless, to help keep the weight down a bit. Nevertheless, the bike seemed sluggish and hard to handle, but the ride was very plush and the tires are robust.

Today, in preparation for a tour that never seems to go down, I put on 38mm RH Barlow Pass Extra Lights. It was as if I had a new bike. Much more responsive, better handling, no toe overlap, and lighter weight. I was about 1/3 faster on the same course (unloaded both times). If I get wise and install fenders, there is now plenty of room.

The only remaining question is whether it is tire size, per se, or whether it is the Endurance Plus vs. Extra Light/fragile tire construction. The handling of the bike is unambiguously better, so I am pretty much sold on the idea of having ~38mm tires for an on road tour, but worry about getting the Endurance version now. (They don't have Endurance Plus.)

Xavier65

These days, the mantra seems to be "The wider the tyre, the lower the rolling resistance", but I have my doubts. Are tourers rapidly migrating to fat bikes?

I appreciate my 50mm tyres for all their plus points: comfort, resilience, grip on/off road, and being impervious to broken glass, thorns, sharp debris, etc.

However, I reckon the 40mm tyres on my old tourer, although pretty wide at that, were better for speed/efficiency.

It may even be the case, that tyres of 30mm width would be even better if speed and efficiency were your objectives.

It's probably a matter of finding the sweet spot through testing, i.e. somewhere between 30 and 50mm. Comfort/resilience vs efficiency?

tyrion

My guess it's the light weight/sidewall suppleness that's the main factor. Unless you're going fast (20 mph) then the aero becomes more of a factor. Or lots of stop/starts then mass becomes more of a factor.

If it were me I'd split the difference and try 44mm Snoqualmie Pass standard casing.

Or you can try Soma Supple Vitesse (tubed) for much less money.

https://www.somafabshop.com/shop/som...attr=3106,4273

delbiker1 

For road riding, I do not use wider than 32mm. The only tires that are too wide, IMO, are ones that will not clear the stays or fork, including rubbing when accelerating or cornering aggressively. Other than that, the riders choice. I can tell the difference between 28 and 32, regarding handling and effort. Going from 55mm to 38mm is huge.

Steve B.

If you were touring, would you be using fenders ?. If so, can you fit a 50mm tire with fenders ?. I had to replace the fenders on my ‘98 Miyata in order to install 38’s. My old fenders mounting brackets were too short to take a tire bigger than a 32.

Polaris OBark

My 55mm tires are too big for fenders. If I put my 38mm tires on (my default road bike tires), there is loads of room.

If I tour down the West Coast in the summer, there really isn't a need for fenders, but anywhere else, I would want them.

(BTW, in both cases, I was going far too slow for aero to matter. Either it is the weight of the bigger tire or the difference in rolling resistance between "extra light" and "Endurance Plus", or both.)

ThermionicScott 

Maybe the increased wheel diameter with 700x55C gave too much trail, and that's partly why it felt hard to handle? The calculator I use gives 67mm trail with 700x38C and 73mm trail with 700x55C.

cyccommute 

Something that today’s trend of ever wider tires doesn’t take into account is Real Physics®. We all know the ol’ “set in motion and it will remain in motion” saw but what we forget is the other part…”unless acted on by a force”. No bicycle (or train or plane or car or truck or ox cart) ever attains that “remain in motion” part. There is no “steady speed” because every bicycle (and that other list) is being acted on by a force. The most common force is air resistance but there is also gravity when the load is lifted and friction of the tires on the ground. All of these conspire to make slow the bike down and cause it to be under constant acceleration. The simple motion of the wheels going around mean that the wheels are experiencing constant acceleration. The acceleration just happens to have a negative sign. Make the wheels heavy with wide heavy tires and the bike is harder to accelerate. Rolling resistance might be lower when it comes to wider tires but the cost of that rolling resistance is more weight you have to shove into the air to keep your speed up.

By the way, I worked out during Covid that we are shoving around 12,000 cubic feet per minute (6’ x 2’ =12 sq ft. 12 sq ft x 1000 feet/minute (12 mph) = 12,000 cubic feet per minute). That’s a lot of air and the only way you are shoving it out of the way is by spinning the wheels around. Yea, wheel weight matters.

elcruxio

Wheel weight doesn't actually matter. Or rather it matters as much as any other weight plus a miniscule fraction that has no practical effect on top.

But a wider tire is less aerodynamic.

Wider also doesn't automatically mean less rolling resistance. It's all a bit complicated, but in essence a wider tire will allow for a lower rolling resistance for rougher surfaces with more system weight. So, more weight => wider tire or rougher surface => wider tire or more weight + rougher surface => wider tire X2.

However tire pressure must also be considered. Tire width on itself meaningless without the correct tire pressure. You can make a 47mm marathon mondial (a notoriously slow tire) roll faster than a GP5000 S TR if one is inflated correctly and the other is inflated completely incorrectly.

However, given how complicated finding the lowest rolling resistance for a touring bike is and the fact that it is certainly not a race, one should probably focus more on using a tire that's wide enough and low enough pressure to be comfortable for the chosen surface roughness. That said 50mm is pretty wide even for gravel. That's already in the XC mtb region of tire widths.

gauvins

For extended touring, I'd go as wide as possible. Road surface can be a challenge with narrow tires. I ride on 52mm. I did a 360 this summer (fell deep in road side ravine etc) without any visible impact on the front wheel, that would almost certainly have been destroyed otherwise.

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Xavier65

I'd use mudguards when touring - given you must cope with rainfall and potentially muddy/puddled routes. I have them on my bike with 50mm tyres.

I used >40mm width tyres on my '83 Claud Butler, and there was plenty of clearance for rear mudguards, but no chance in hell on the front. Fortunately, there exists a mudguard that attaches to the downtube, which I found perfectly acceptable. It is rare that you go at speed at a turn in wet conditions, and the splash tends to be directed away by that point anyway.

rumrunn6

talking out loud to myself ...

got a hybrid that takes wide tires. kind of an urban bike. which I had wanted for years, because I thought it would be better for me off road, than the entry level hybrids I was trying. in the interim, I got a mountain bike & it's been great. kept my road bike & regular hybrid bikes. this additional bike, that now has very wide tires, initially disappointed me because I felt so much slower, regardless of what wide tires I put on it. maybe it's some geometry stuff too? anyway, I'm not getting rid of the old hybrid just yet & I'm trying to find rides suited for this wide tire bike. but it's tough because most dirt I ride also has rocks & roots, which the MTB handles better. so I'm keeping the road bike w/ 25mm tires, the hybrid w/ 40-45mm tires, the mtb w/ 2.25" tires & the new to my hybrid w/ the 2.165" tires

there's always the law of diminished returns. is that even a law? some examples
working more hours makes you more productive, but if you work too many hours, you become less productive (pr hour)
I think the wider tires makes you faster idea, just applies to small increases, not going from 25mm to 2+". just look at how slow & hard to pedal fat bikes are

so now I have 4 bikes & many different kinds of rides that I like to do. so the variables went up exponentially? (not a mathematician) 4 bikes x at least 2 different tire types & sizes for each? how can I ever decide what to choose? I'm working on it. & I waited so long to get this new to me bike, that I don't want to ditch it just yet

Tourist in MSN

I have toured on 37mm, 40mm, 50mm and 57mm tire widths. I am not familiar with the different grades of tires you mention (Endurance or Plus or Extra Light), but I can say that in my opinion the tire width did not play a big part of rolling resistance. Instead suppleness of the tire sidewalls, tread, fabric, and any extra armor layers inside play a much bigger roll in rolling resistance. I usually use Schwalbe tires for touring, but I have never owned any of their Plus tires, simply because they are known for a lot of rolling resistance.

If you are riding at about 14 mph, that is roughly 20 feet per second. Two tires means that you are flexing 40 feet of tire every second and it takes a lot of energy to flex 40 feet of tire. So, the more flexible and supple your tire is, the less rolling friction. Tire pressure also comes into play, a tire with a stiff casing and low air pressure will be VERY slow. But too high a pressure to reduce flex and your ride is less comfortable. And there are limits to tire and rim strength for pressures.

For a highway tour, I choose 37 or 40mm tires. I use 50 or 57mm tires on tours where I am going to be on rougher terrain, such as gravel, rail trails, off road, or 4X4 roads.

Exception, I have ridden on some really rough chip seal in West Texas. If I was going to go on a tour where I knew in advance that there was a lot of rough chip seal, I might take a wider tire instead.

ThermionicScott 

It's too bad RH doesn't make a 650x55B tire. It would make for a wheel that's a lot more comparable to your Barlow Pass in weight and diameter, leaving aero concerns to make the difference.

79pmooney

My engineering brain says you are wrong, that if you pedal smoothly you aren't accelerating that mass so the added work required is only from additional wind, tire, etc. resistance. But my legs tell me over and over that light wheels are a joy to propel. I now have a bike with 330 gm rims (really - weighed), DT Revolution spokes and 300 gm or less tubulars. 25c front, 23c rear. (Both the largest conservative fit for that pure '80s race frame.) Only drawback - wind resistance. No, not the tires. Bike's so much fun I ride faster. And every acceleration - what a difference! When I raced, these weights were my training/club race wheels. Down to 290 gm rims and 250 gm tires for the "real" races. For this guy with no fast twitch muscle and not a lot of the rest, those wheels got thanked every corner, every field acceleration. If I was 25 all over again now, I'd still be pushing the tire/rim weight boundaries because all the aero in the world would be little help if I got dropped coming out of a corner or missed a split in the field.

PedalingWalrus

for me the sweet spot is 40mm tire. I have some Surly Extraterrestrials on another bike and most of the time it seems like an overkill.


The funny part is that when it comes to ride singletrack I seem to think that anything narrower than 4" is not bouncy enough so I end up mostly biking on 40mm tires for bikepacking and bike touring and using a fat bike for singletrack, snow and sand

Polaris OBark

If it is mass rotating in a circle (or any curved trajectory) it is accelerating.

Also, my "problem" shows up when I am (slowly) climbing steep hills. On the flats, those tires aren't problematic.

79pmooney

And to to thread title and question - tires how wide is too wide? Easy. You won't be able to turn a too wide tire once you've inflated it. Downsize one size for possible, two for practicable. From there it is a matter of taste. (Ben ducks under the table for shelter from the tossed debris.)

Polaris OBark

A large part of the reason I got the 55mm wide tires was simply because they would fit in this frame. (Just because you can do this, doesn't mean you should.)

pdlamb

Technically the rim and tire are accelerating, but the angular momentum doesn't change at a steady speed. It's all born by the structure of the wheel, so your legs don't have to exert force through the drive train to maintain that rotational acceleration -- only to overcome the aerodynamic drag and tire hysteresis.

Polaris OBark

or to climb...

79pmooney

But that acceleration is opposed by the spokes, not your legs. A bicycle made with steel train wheels and run on a steel track will take very little to keep it moving despite all that mass being constantly accelerated. Now with a typical 700c or 27" wheel the rim and tire happen to be at a radius where the rotating inertia is almost exactly the same as the straight line inertia from the speed. So that rotating weight is resisting you twice as much as the weight anywhere else on the bike (or in your gut)

Tourist in MSN

I really liked having 57mm wide tires on this trip. That is the biggest I could use in this frame.



About two thirds or three fourths of this trip was on pavement, but these older Marathon Extreme (discontinued) tires roll very well on pavement, although they are quite noisy.

cyccommute 

Smoothness of pedaling doesn’t really work into the equation. Any force you are working against has an acceleration component. It’s right there in the equation for force…F= mass x acceleration. All of those things you are “working” against are forces with negative (to you) accelerations. Yes, lighter wheels and tires are much easier (and more fun) to accelerate but that is because they require less force to accelerate. While in theory, heavier wheels and tires should maintain speed longer, the problem is that only works for flat, straight line travel ideally in a vacuum. The real world is filled with hills, corners, and lots of air that you have to fight against…”work” in physics. That makes heavy wheels and tires a detriment.

cyccommute 

History is against you here. If wheel weight didn’t matter, why not just use steel wheels? They would be much stronger and less prone to the various failures that bicycle wheels experience. Every vehicle from bicycles to trucks have undergone significant weight reduction in the wheels over the last 50 to 80 years. Very few trucks run exclusively steel wheels anymore. Most all of them have aluminum wheels which reduces weight an insignificant amount compared to the weight of an over the road truck…80,000 lb (36,000 kg). An aluminum wheel on a truck is only going to save the truck a few pounds at most but the steel ones are worth replacing due to the weight difference.

Just to be clear, I’m not talking about the aerodynamic effects of the tire itself. I’m talking about the force needed to move the bicycle through the air and the impact that having heavier tires and wheels has on the work done. Heavier tires are harder to keep rolling because of the work needed to move them. Work in physics is defined as force acting over a distance. Force is related to mass. For more mass more force needs to be applied over a given distance. Less mass means less force needs to be applied over that same distance. Going back to that automotive example, alloy wheels are used because they require less work and, therefore, less fuel. If the small weight difference has such an impact on a heavy, highly powered vehicle, think of how much impact it has on a lighter, far less powerful vehicle. We are talking hundreds of horsepower (car) vs a fraction of a single horsepower for a bicycle.

Far too much is made of rolling resistance. Yes, it is important but not as important as rotating mass and/or the work needed to move the bicycle. Small differences in rolling resistance might win a bicycle race but we aren’t talking racing here.