Jim Yes, you should be able to do that. Steve got the rim part right, but the tire part has a small mistake. You don't half the tire width for this calculation.
Your existing 700x32 wheel, which barely clears the brake bridge is (622/2)+32 = 343mm in radius and barely clears the brake bridge Your 650bx42 will be (584/2)+42 = 334mm in radius. You will have 9mm of additional clearance under the brake bridge, with Hetres. That same 9mm is what you use for estimating your change in BB height. Your bike will be 9mm lower to the ground when you go from 700x32 to 650x42. Additional tire deflection when you get on the bike might be worth considering, as well, but that 9mm is a good start. You use the full tire width when estimating wheel radius, not half the tire width, as Steve indicated above. You would take half the difference in tire width when you look at the sideways clearances, between the chainstays and the fork blades. A 42mm tire will be 5mm closer to the chainstays and the fork blades, so you need to check there for potential clearance issues. On Thursday, November 14, 2013 8:22:03 AM UTC-8, Jim Bronson wrote: > > OK, so I should be able to run Hetres with fenders then. > On Nov 14, 2013 9:40 AM, "Steve Palincsar" <pali...@his.com <javascript:>> > wrote: > >> On 11/14/2013 10:21 AM, Jim Bronson wrote: >> >> OK, so 19+5=24. I majored in liberal arts. What is the significance >> of the answer? A 650bx42 tire is 24mm smaller than a 700Cx32 tire? >> (assuming sizes printed on the sidewall are more or less correct). >> >> >> 19mm is the additional clearance you get because of the smaller rim. As >> you can see, I'm a liberal arts major too: you lose 5mm, so you have to >> subtract rather than add it because the tire is larger, so you have a net >> gain of 14mm clearance. I should have said "add back", that's what I meant. >> >> >> >> >> On Thu, Nov 14, 2013 at 7:31 AM, Steve Palincsar >> <pali...@his.com<javascript:> >> > wrote: >> >>> On 11/13/2013 11:54 PM, Jim Bronson wrote: >>> >>>> I had short reach brakes before with 700x32mm tires and they barely fit >>>> under the brake bridge. Don't know what that converts to in 650b >>>> >>> >>> subtract the difference in radius (622 - 584 /2) of the smaller rim and >>> add half the additional width (42-32 / 2) of the new tire >>> >>> >>> >>> >>> -- >>> 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-bun...@googlegroups.com <javascript:>. >>> To post to this group, send email to >>> rbw-owne...@googlegroups.com<javascript:> >>> . >>> Visit this group at http://groups.google.com/group/rbw-owners-bunch. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >> >> >> >> -- >> Keep the metal side up and the rubber side down! >> -- >> 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-bun...@googlegroups.com <javascript:>. >> To post to this group, send email to >> rbw-owne...@googlegroups.com<javascript:> >> . >> 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-bun...@googlegroups.com <javascript:>. >> To post to this group, send email to >> rbw-owne...@googlegroups.com<javascript:> >> . >> 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.
