51 mm to narrower tires: benefits for rolling resistance and handling?

[Patrick Moore]

The pavement wheelset for the 2016 Matthews road bike for dirt is shod with 51 mm actual on 27 mm IW rims/48 labeled Soma Supple Vitesse SLs, 360 digital grams, and tomato skin thin. You’d think they’d roll like butter on ice.

But compared to the former 61 mm 450 gram ultralight 700C Big Ones, they “feel” as if they require extra effort to keep moving; this consistently over ~18 months in identical conditions. (I jettisoned the Big Ones because, while Schwalbe called them their fastest rolling tire, bar none when they came out ~10 years ago, and IME they lived up to this description, they made the bike wallow in turns. The Somas make the bike handle as I asked Chauncey to make it handle, like my Riv Roads; at least, as close as 29” fat tires at 17 to 23 psi can do that.

I chose the Somas as allrounder tires that would ride well on pavement but be fat and soft enough to handle at least shallower sand. They handle very well on pavement, roll somewhat sluggishly on pavement, but their rounded profile ploughs in sand; not good.

So, since I do have a second, Thunder Burt wheelset for off road, I don’t need 50 mm tires on pavement; thus the questions:

1. Would I gain any advantage in handling, or even rolling resistance, do you think, by swapping them for narrower road tires; say 44 mm Snoqualmie extralights (I’d use tubes)? The Rims — Velocity Blunt SS — are 27 mm wide inside. Extrapolating from the information on the SP web page I’d guess these would measure 45-6 on the Blunt SS rims.

2. The bike was designed for 700C tires between 50 and 60 mm (with fenders) and 650Bs up to 75 or 80 mm wide, tho’ ‘ve never used the latter. I realize that this is a very general qeustion, but is there a rule of thumb for how narrow you can go on a given frame designed for wider tires without degrading handling?

Note: if you don’t have statistics, anecdotes welcome!

Anecdotal case in point for degraded handling: on NORBA-type rigid mountain bikes, designed for 50s, 35 street tires felt OK tho’ handling wasn’t sparkling. With 23 mm tires (26X1” Turbos) it was bad indeed (oddly, degraded both straight line stability and cornering stability), tho’ they made the bike fast in a straight line. OTOH, with 60 mm actual Big Apples my old Diamond Back handled superbly on pavement, if a bit staidly.

Any thoughts?

Thanks, Patrick

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

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[ascpgh]

My two cents: You can exceed the ideal handling of a bike with a tire size. Just because it can be done doesn't mean you should or that goodness will follow the intention.

I do not limit my observation to the analysis of head tube angle, fork offset, and wheel size. You can easily (sort of) diagram how all of that will play out in the alteration of the bike's trail dimension when shod with the objective tire. Many influences make a frame and a complete bike handle as they were designed. I have had an up-sizing and a down-sizing experience, illustrating the importance of the design of the bike.

My down-sizing lesson was on my 1989 StumpJumper that was optimized for 1.95" tires. I mounted some 1.5" Ritchey Tom's Slicks for my weekday commuting, believing I'd gain a magical reduction of rolling resistance and cornering grip. The roll was much easier, but the awkwardness was introduced to the front geometry by the downsized tire converted the smooth handling bike into an awkward one with abrupt transitions at unexpected moments due to the angle of steering, angle of lean, and speed. The gain of rolling efficiency only seemed to bring me to the unpredictable edge of handling that would require countering in some manner.

My up-sizing was on my Rambouillet, which I had been riding with 28 to 32mm tires. I wanted more cushion for smoothness when riding on unpaved surfaces and tried some 38s with the fenders off. Wow, not ideal. At all. The subtle coordination of a well-provided design, its dimensions, geometry, and tube selection in my size became obvious. That bike is designed around the 32mm tire. Under the sag under my weight and intended loads, all of my bike's details come together for a seamless riding experience, not counting the low-speed seated pedaling zig-zagging from flop that several others have noted over the years. 

I also put 2.2" HardPack II tires on my '86 RockHopper, eagerly anticipating riding the trails up to and down the Continental Divide in the area around  Spar City and Creede in Mineral County, CO. Also not ideal. Floppy sidewalls were overcome by lazy steering and long stays, initiating several oversteering wipeouts as the sidewalls collapsed under load. Not a problem of underinflation, the point of the tire was being able to ride on paths best described as paved with baby head-sized stones. Those separated sharp edges required pretty robust inflation to avoid pinch flats. The bike design just transmitted loads abruptly to the tires by steering input and pedaling when turning because of the longer (pre-NORBA geo) stays and slack steering. 

Lots of individual conversations will ensue about how the rest of the bike and its tendencies can have effect on steering and handling.

Andy Cheatham

Pittsburgh

[J G]

Anecdotally speaking.  My experience with 26er city conversions always left me with a sweet spot for 1.75" tires, downsizing from original 2.2". Regarding Big Ones and 44 mm Snoqualmie extralights, I have the Big Ones on my Willits Scorcher and the 44mm Snoqualmie extralights on my Rosco.  Unless your framest had an exceptionally low BB to begin with, the change in BB height and trail is limited and I would have no concerns making that swap if I was unhappy with the wallow on the Big Ones.

-Justus

Mpls, MN

[Patrick Moore]

Justus: Thank you, your report confirms my biases so I am very pleased to hear it. May eventually try this while procrastinating on a light road bike decision. Actually, I’ll keep an eye out for used SPs offered onlist and, also, wait until my 100 or 200 mile experiment/s with TPU tubes and Orange Seal regular formula play out. 

One pain for such a trial: Getting the Somas onto the Blunt SS rims was the most difficult tire mounting job I’ve ever done, and that was having done many difficult ones, and that was also without tubes involved. So removing them is going to be a RPITA, tho’ from my experience with 3 models of RH tires getting SP’s onto the same rims with tubes ought to be much easier.

Andy: Thank you for the thoughtful and very useful analysis. From my limited (I think I owned 2 MTB frames of similar vintage) experience of pre-NORBA mtb frames, I’d also guess that installing tires much any amount narrower than the design sweet spot would result in awkwardness. On several NORBA-era frames, tho’, ~35s (measured more like 33 or so on the narrow rims I fancied) didn’t handle awfully; not excellently, but not horribly. But as I said, when it got down to 22 mm actual, things got nasty, much as you describe.

On my blue Ram, I used 32s (1.35 mm Kojaks) and perhaps 29-30s (“open tubular” Paris Roubaixs) on Open Pro rims (both under fenders) and the handling was, I guess, perfectly Ram-like, tho’ a wee bit staid for my taste. 

50 mm, at least for road tires with rounded profile, seems to be the pavement handling sweet spot for the Matthews dirt road road bike, and after all that has been said, I’m inclined to undertake the expense and work of installing some Snoqualmie Passes — eventually. If I do, I’ll report on any improvements or declines in handling and rolling “feel.”

BTW, I haven’t ridden the gofast with front TPU tube and OS for 6 days, and the bike has been hanging on the wall ever since. I just checked air loss: front: taking into account a clumsy initial application of the pressure gauge just now, the front has lost a bit more than 5 psi while the rear butyl has lost about 5 psi; I’d say that the TPU air loss still qualifies as “normal."

On Sun, Aug 31, 2025 at 10:03 AM J G <cjus...@gmail.com> wrote:

Anecdotally speaking.  My experience with 26er city conversions always left me with a sweet spot for 1.75" tires, downsizing from original 2.2". Regarding Big Ones and 44 mm Snoqualmie extralights, I have the Big Ones on my Willits Scorcher and the 44mm Snoqualmie extralights on my Rosco.  Unless your framest had an exceptionally low BB to begin with, the change in BB height and trail is limited and I would have no concerns making that swap if I was unhappy with the wallow on the Big Ones.

-Justus

Mpls, MN

 

On Sun, Aug 31, 2025 at 7:53 AM ascpgh <asc...@gmail.com> wrote:

My two cents: You can exceed the ideal handling of a bike with a tire size. Just because it can be done doesn't mean you should or that goodness will follow the intention.

I do not limit my observation to the analysis of head tube angle, fork offset, and wheel size. You can easily (sort of) diagram how all of that will play out in the alteration of the bike's trail dimension when shod with the objective tire. Many influences make a frame and a complete bike handle as they were designed. I have had an up-sizing and a down-sizing experience, illustrating the importance of the design of the bike.

My down-sizing lesson was on my 1989 StumpJumper that was optimized for 1.95" tires. I mounted some 1.5" Ritchey Tom's Slicks for my weekday commuting, believing I'd gain a magical reduction of rolling resistance and cornering grip. The roll was much easier, but the awkwardness was introduced to the front geometry by the downsized tire converted the smooth handling bike into an awkward one with abrupt transitions at unexpected moments due to the angle of steering, angle of lean, and speed. The gain of rolling efficiency only seemed to bring me to the unpredictable edge of handling that would require countering in some manner.

My up-sizing was on my Rambouillet, which I had been riding with 28 to 32mm tires. I wanted more cushion for smoothness when riding on unpaved surfaces and tried some 38s with the fenders off. Wow, not ideal. At all. The subtle coordination of a well-provided design, its dimensions, geometry, and tube selection in my size became obvious. That bike is designed around the 32mm tire. Under the sag under my weight and intended loads, all of my bike's details come together for a seamless riding experience, not counting the low-speed seated pedaling zig-zagging from flop that several others have noted over the years. 

I also put 2.2" HardPack II tires on my '86 RockHopper, eagerly anticipating riding the trails up to and down the Continental Divide in the area around  Spar City and Creede in Mineral County, CO. Also not ideal. Floppy sidewalls were overcome by lazy steering and long stays, initiating several oversteering wipeouts as the sidewalls collapsed under load. Not a problem of underinflation, the point of the tire was being able to ride on paths best described as paved with baby head-sized stones. Those separated sharp edges required pretty robust inflation to avoid pinch flats. The bike design just transmitted loads abruptly to the tires by steering input and pedaling when turning because of the longer (pre-NORBA geo) stays and slack steering. 

Lots of individual conversations will ensue about how the rest of the bike and its tendencies can have effect on steering and handling.

Andy Cheatham

Pittsburgh

On Sunday, August 31, 2025 at 12:46:53 AM UTC-4 Patrick Moore wrote:

… 1. Would I gain any advantage in handling, or even rolling resistance, do you think, by swapping them for narrower road tires; say 44 mm Snoqualmie extralights (I’d use tubes)? The Rims — Velocity Blunt SS — are 27 mm wide inside. Extrapolating from the information on the SP web page I’d guess these would measure 45-6 on the Blunt SS rims.

[Garth]

Sure, why not ! I just went from 50mm(47mm actuall) Big Bens to 38mm Marathon Racer tires on my Bombadil. This is for road riding. The steering front end handling is fine, but I'm also accustomed to road bikes that have a lower trail and steer even quicker. The minor change here is nothing like that !  The weight difference is 300g per tire difference, which is noticed. Steering is more precise, for sure.

"Back in the day" of ye 'ol '83 Stumpie I tried some 1.5" TriCross tires, from the stock 1.95". Other than not as much cush, it was nothing drastic by way of handling on or off road. I tried some 2.2" Vittorias that had an oddly flat profile., they were okay offroad but horrible on it.. 

All in all I always liken changes of tires widths to mechanical pencil leads. 3mm lead is like a 23-25mm tire, it just traces a finer line. More precision and detail is possible.  The larger diameter lead, the more surface area the lead covers and isn't as precise. Same with tires. On a bike built around a 50mm tires about as low as I'd go is a 38mm tire. 55mm tire, a 40mm tire.

Since your Mathews is patterned after a Riv of yours, I think you'll be fine as it's likely in the 60mm of trail range, give or take 5mm. The difference in tire widths you're speaking of isn't going to make or break your world.

Those Kool-Stop Tire jacks are supposed to help with really tight tires. I have one but have had no cause to use it yet. The Crank Bros Speed-lever thing I have my doubt it would survive a tight tire.

[Patrick Moore]

Great, thanks, more confirmation of my biases. Per the rather sketchy information Chauncey gave me the Matthews RBFD has a 71* hta, 55 mm of rake, and with a 50 mm tire, 68 mm of trail. With a 44 the trail is 65 mm.

Chauncey was guessing; I guess he didn’t keep very precise records. 

Or was the hta 71.5? No matter, the difference in resulting trail is only 2 mm, which I think is not much.

Trail of  64/62 50/44 with 71* and 61/59 at 71.5*.

My first edition (2010) Fargo was designed for 60s, or at least, I used 60 mm Big Apples, but I had a second wheelset with1.35 mm Kojaks and, tho’ it has been a long time, i don’t recall that the skinny tires made handling horrible.

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[ascpgh]

Every bike's distribution of rider/bike weight can change how it responds to the slight alterations of the trail.  Other collected dimensions may moderate adjustments of it better than others. 

Going to bigger tires on my '86 RockHopper concentrated the forces of that particular riding on the tires' sidewalls. While generally OK,  the slack steering and longer stays made the bike directionally stable, but when trying to change direction, it took big inputs instead of the nimbler geometries of '89 and on. Those high efforts on the trail twisted the sidewalls at low speed, and if I actually was at speed and got the front end on a line around a corner, hard pedaling would collapse the rear the same way. All of that while adequately inflated for the general riding. Its insufficiency for those peak inputs made me overinflate to prevent them, and eliminated the perceived benefit of the more balloon-ish tires. 

A similar assessment can be made regarding the larger tires on my Rambouillet; it was just at a scale that brought it on with less added tire size. Care in choosing your low personal tire pressure when riding supple tires still requires you to be adequate for some percentage of your riding and accept the odd minority situation, or pump them up to account for every situation. My reasons for going big and supple make me accept less inflation than what would be appropriate for 100% of possible situations, and I ride (more comfortably) aware of the limitations that it brings.

It's a big live and learn thing. A personal preference from the perspective of the bikes I've had, where I've ridden, and what I will tolerate as part of the adventure in my travels.

Andy Cheatham

Pittsburgh