Tubes are not all that finicky when it comes to sticking them into a tire casing. I've used reeeeeeaaaaallllly small tubes in bigger tires with little direct issue on smooth roads. You can also go up a size or so on the large end, though if you have a rim which doesn't get a good bite on the tire bead, you do run the risk of blowing the tire off the rim when you increase pressure.
I found on the CX courses that going up one size actually meant fewer pinch flats - my working theory was that since you are at the low end of the range, the rubber is perhaps not stretched as thinly when you hit something. Of course, that was non-rigorous testing. Though I have in general tended to puncture more with undersized tubes both on courses and IRL. I wouldn't hesitate to use the 43's. In fact, that's what I bought last time I was there. hope that helps, - Jim -- 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/d/optout.
