[RBW] Re: fatter tires for smaller diameter wheels
There is also the factor of what you get used to. Someone who rides 700c all the time, gets on a 26 inch wheel road bike, geometry adjusted or not, and declares it not stable, or whatever. Especially of someone has been on big wheels for all their adult riding career, as most of us have. I bought my 26 inch wheel Riv from a gal who had all 700c wheel bikes. She did not like the handling, and the top tube was too long for her. Ok, fit me perfect, with the bars below the saddle. I rode, exclusively, my 700c Riv up until I got that 26 incher. I did not like the new bike at first. After a month, i was sold. The geometry was optimized by Grant for this size wheel, and it does ride different than a bike with larger wheels. Since 06, i think have ridden 700c maybe three or four times. Ymmv Mark Howtostretch.com On May 11, 3:38 pm, "cyclotour...@gmail.com" wrote: > 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 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 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
[RBW] Re: fatter tires for smaller diameter wheels
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 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 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.
[RBW] Re: fatter tires for smaller diameter wheels
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 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.
