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 <[email protected]> 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 <[email protected]> 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. >> >> 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 >> >> -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/rbw-owners-bunch/CALuTfgt%2B3UK_MBnTEbDEiKTBi%2BufdUB3t2d6LqGbOTr-3o0%3DNw%40mail.gmail.com.
