Originally Posted by
shuru421
Might sound like a no-brainer but..
Will downsizing wheel size give more clearance for wider tires?
Also Im reading 650b wheels are actually comfier, stronger, faster acceleration, better handling. Good foundation for a touring (racks,panniers, etc) bicycle wheelset?
’87 Marinoni Sports Tourer takes 700C 32’s and short reach dual pivot brakes with pads at the the bottom of the slots.
It has fork and chainstay clearance for 650B 38’s with fenders (and decent fender clearance), thanks to the relatively generous width at those points. Very happy with Tektro 556 (predecessor to 559) dual pivot brakes (all with KoolStop salmon pads). Gratuitous second photo to show the pretty polished stainless Berthoud fenders.
It will even take 650B 42’s, but no fenders. (I prefer the 38’s for several reasons):
Comfier? Definitely, since I can run the 38’s at 45-55 psi, versus 32’s at 65-75 psi.
Stronger? Spokes are shorter, but no real change in “strength”, and not sure how that would be determined.
Faster acceleration? Same cogs and rings result in 4% lower gearing (38’s versus 32’s), and the smaller wheel+tire circumference results in slightly quicker spin-up. (BTW, tires in all cases shown are Compass/Rene Herse with Extralight casings on tb14 and Pacenti rims, nearly as light as available.) I also switched from 175mm cranks to 170’s, although there was never a clearance issue (never have been a “pedal through the corners guy”). My knees with seven decades of experience liked that change!
Better handling: There’s minimal, if any, change in steering, but the extra tire width gives better cornering grip, although I’m not one to push that limit! But that tire width also means that it’s noticeably less sensitive to pavement seams, etc. which results in more “relaxing” rides on crappy Seattle streets.
Good foundation for touring? Definitely! But remember that the frame geometry hasn’t changed, so if the bike was decent for touring before, the 650B conversion will certainly help. But it won’t make a racing frame into a tourer. For that you should consider front loading, especially if you rerake the fork for lower trail. (I’ve done that to my other bike with excellent results, but it wasn’t a good 650B conversion candidate.)
A significant improvement at my age is that the 650B version is easier for these old hips to get my leg over the top tube!