Originally Posted by
Andy_K
She's trying out cycling as a replacement for jogging, which has been too stressful for her joints, so I think this will be more than just the typical roaming the neighborhood that I did at that age. Still, 1x isn't a bad idea.
The tires that are on there now are labeled as 25s but measure 23. I might need to dimple the chainstays to make 28s fit. 650B with 28s would make a lot of sense for this bike. If I could find a reasonable set of used wheels, I might splurge for 650x28 Conti GP 50000s.
I have that exact Katana in a 58 size frame. It really surprised me how responsive and comfortable it is to ride.
As to tires I have some info. Mine came with 25s also but they were to aged to use so I put a set of 28 Continental Top Contacts on it and ran into a brake scraping issue in the rear as there was less than 1mm of clearance but the TCs have thick tread. I solved the problem with a brake caliper upgrade to some 6208 brake calipers and got marginally better clearance. After a few rides I threw on a set of GP 4 Seasons 28s and they fit great. I might be able to squeeze a set of 30mm tires in if they were true 30mm but I'm happy with the 28s. I did not try the GP 4 Seasons with the original calipers in place but I think it would have been a tight fit.