I've had three 700C tandems, and only my current one will fit a true 40mm tire. I can't understand running a tandem with anything less, but apparently tandem purchasers have succumbed to the same marketing that accompanies single bikes.
I would eventually like to get one of the new Co-Motion 29er Javas just so I could run 60mm tires on it (probably Big Apples). Cheers, David "it isn't a contest. Just enjoy the ride." - Seth Vidal On Sun, Jan 5, 2014 at 1:52 PM, ted <ted.ke...@comcast.net> wrote: > If anyone is interested, a quick google search turns up > http://www.terrymorse.com/bike/rolres.html > > Racing motorcycle tires (or even street legal sport bike tires) have > nearly nothing in common with bicycle tires. Which doesn't mean they cant > both provide reduced traction when overinflated. The motorcycle tires get > part of their stick from practically melting and bonding to the road as > they deposit rubber on the track. Traction tends to increase as tire > pressure is reduced until the tire really melts and the ride feels a bit > like you'r on a liquid film. An under inflated tire will overhead and can > be ruined in very short order (expensive mistake, ouch). Tire pressure and > temperature are very big deals for race bikes. I think I recall reading of > a bike that had IR temperature sensors on it to get tire temperature data > while doing laps. I once saw a real (non DOT legal) front race tire. It had > a nearly triangular cross section in the tread area, distinctly not round, > though the exact center was kinda circular with a fairly small radius. I > guess that was done to make it "turn in" quicker, but the thought of riding > such a thing didn't appeal to me in the least. > > Since a tandem with riders is on the order of twice the weight of a > single, I find it really surprising there isn't more difference between the > tires used on tandems and singles. Is a ~40mm tire on a tandem really > "wide"? Surely its not as far from the mainstream as using a ~40mm tire on > a single road bike is, is it? > > On Sunday, January 5, 2014 12:01:02 PM UTC-8, Tim McNamara wrote: > >> >> On Jan 5, 2014, at 12:42 PM, ted <ted....@comcast.net> wrote: >> >> > Does anybody else remember Jobst asserting back in the early 90s that >> tubulars were slower than clinchers because of the glue? I think the "... >> flattening was more pronounced in tubulars than clinchers." that Tim >> mentions was part of his reasoning. >> >> Back in rec.bicycles.tech years ago, Jobst noted the different shape of >> the curve for tubulars and came to the conclusion that the tubulars were >> squirming on the glue bed, road tubular glue being somewhat soft to allow >> the tire to be removed and put back on or replaced without having to put >> more glue on the rim. Track riders long used shellac to adhere the tubular >> to the rim, which forms a hard bond with no flex; once the tire is removed >> (with difficulty) new shellac has to be applied to glue the new tire on the >> rim; Jobst thought that a hard glue like shellac would eliminate the losses >> and that tubulars would then show the same curve. I don’t know if that was >> tested. >> >> FWIW, IIRC the Avocet tire tests were done with an asphalt covered drum >> instead of a smooth steel drum. IIRC Jobst also did slip angle tests by >> riding on an asphalt covered wood platform, finding that bike tires slip >> out at a 45 degree angle to the ground. I wonder if there is a difference >> in the slip angle based on tire width and/or inflation pressure. Racing >> motorcycles appear at times to get below 45 degrees, although as I am >> looking at head-on photos of cornering racing motorcycles that may be an >> illusion of camera angle. >> >> I have been reading Jan’s book on Rene Herse, which my wife gave me for >> Christmas. There is a great photo (one among many) of a tandem >> (Prestat/Herse, I think) rounding a downhill corner with another >> immediately behind. While they do not appear to be at the cornering limit, >> the bike is on the inside of the turn on rough and perhaps gravelly >> pavement and yet appears quite sure footed- at least the riders don’t look >> at all alarmed. It appears to have 650B x 42 tires or thereabouts. I have >> felt that wider, softer tires seem more secure in corners (although >> consistent with my earlier posts I don’t know if that is actually true >> versus an assumption) than skinny hard tires. I had a demonstration of >> this back in my track racing days when I punctured my front wheel (track >> tubular at 110 psi, maybe 20-21 mm wide) and borrowed a front wheel from >> another competitor. His wheel had a 700 x 19 or so Continental Grand Prix >> pumped up to 140 psi or something like that. It felt incredibly unstable, >> like it was on ball bearings so there was no resistance to the handlebar >> swinging back and forth, really quite unsettling although it didn’t slip or >> do anything untoward on the boards. I was glad to give him his wheel back >> at the end of the night. > > -- > 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 rbw-owners-bunch+unsubscr...@googlegroups.com. > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > Visit this group at http://groups.google.com/group/rbw-owners-bunch. > For more options, visit https://groups.google.com/groups/opt_out. > -- 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 rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/groups/opt_out.
