I think tire circumference was part of the discussion as well, not just mass???? IIRC there was a sweet spot in circumference that you couldn't get in a 26" wheel w/out a larger tire.
On May 11, 3:34 pm, doug peterson <dougpn...@cox.net> wrote: > Hopefully Jan will chime in on this if I've mis-understood the test. > The BQ article was well thought out and executed, and a good read. My > understanding of the test was that the bicycle geometry was a > constant, and the object was to explore how various combinations of > wheel size and tire width impacted handling. The conclusion was that, > regardless of wheel size, there was a range of moments of inertia > within which there 26", 650B, and 700c wheel / tire combinations with > similar handling. Wheel / tire combinations below this range were > overly sensitive, and ones above were sluggish (my terms, not BQs). > > IMHO handling is subjective so what one rider prefers may not be > optimal for another. Just for fun, I ran the numbers on my Atlantis' > touring wheels / tires and of course it's way out on the sluggish side > of the scale (what a surprise!) but performs well for my loaded > touring. The 3 testers are more performance oriented riders and > prefer more responsive handling. > > We had a thread here a while back about optimal width for 26" wheels > where many responders liked 1.75" (+/-) widths for touring & general > riding. Before that, I had put some 1.25" Panaracer Urban Max tires > on my old 26" MTB grocery getter, with not a thought to handling. I > found it skittish & went up to 1.75" & it significanlty increased the > stability. The old MTB was probably designed for 2" knobbies, so the > 1.25" street tires were definitely sub-optimal. > > dougP > > On May 11, 2:31 pm, Michael Gordon <meisengor...@sbcglobal.net> wrote: > > > > > > > > > List, > > > I just read a post from Patrick Moore with thread title "to make 26" > > rim'd atlantis fast randonneur: suggestions?", the quote is, "Jan's > > idea that smaller wheels ought to have fatter tires for the best > > handling compared to larger wheels has not been true in my > > experience." I have read similar statements from others and wanted to > > comment. > > > I did actually purchase the Bicycle Quarterly (BQ) article, although I > > don't have it on hand as I write. As I recall, the handling of 3 > > bikes with similar geometry but different wheelsize was compared. The > > BQ conclusion was that the bikes handled differently depending on tire > > width, and the purported explanation was that the moment of inertia of > > the wheel was the cause of a difference in handling. Since wider > > tires are generally heavier, and smaller diameter wheels light, one > > may infer the recommendation that smaller diameter wheels should have > > wider tires than larger diameter wheels. > > > Here's what I want to challenge: the geometry of the 3 bikes was > > similar, I believe they all used a 73 degree head angle. So yes, if > > you want to keep the head angle constant as wheel size changes (and it > > is a head angle commonly used for road bikes with 700C wheels), then > > probably a mountain bike diameter 26" wheel and a skinny tire is not > > the best combination. > > > However, bike designers (at least the better ones) know to change > > (decrease) the head angle and other aspects of the frame geometry for > > a smaller diameter / similar tire width wheel precisely because the > > steering of the smaller diameter and lower moment of inertia wheel is > > quicker and the stability is less. So, I don't think the BQ article > > proved a 26" wheel bike has poor handling with narrow tires, it just > > showed that if the geometry is taken say from a design that works well > > for narrow 700C wheels and no compensating changes are made, the > > handling will be sub-optimal. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
