Tandem Cycling - Custom Climbing Cassette

Well we like close ratio cassettes, but need to climb steep stuff often. First we changed the 30 ring to 28. This is on 9speed shimano, but will work on 10speed too.

Started with a 12-23 9speed d/a cassette. Changed the 12t out for an 11t, since "if you need to be in your 12, you need to be in your 11" 95% of the time. On climbing days I remove the 16t and install a Miche 26 separate cog. This keeps more mid-range close ratios than a sram 11-26. It works even better on a 10-speed set-up.

I've never used a cassette, only freewheels. My leg strength isn't what it used to be, so the only reason I have to put anything on my tandem's rear smaller than 14 is to go downhill fast. OTOH, going up hills has to be a study in patience for me. But I did run out of gears with the current 13-32 freewheel, going down a long hill on a bike path near my house. Disappointed both me and my 10-year-old stoker son - the pedals was a-whizzin, but we couldn't go no faster. So I started looking for a 12-tooth smallest cog, pretty rare among freewheels.

Other part of the story, is that I wanted a BIG cog for going the other way, up those hills. Turns out to be almost impossible to find a stoker's chainwheel smaller than the 39-tooth POS Sakae the bike came with (118mm BCD, yuck). So now two freewheels are on the way: A 12-34 7sp, and a 14-38 (yes, 38) 5sp for experimental purposes. The 5sp might wind up on my Super Sport, we'll see. But if I run out of gears with that 12-tooth on the rear, I probably didn't want to go that fast anyway, even if my stoker did.

For the original poster it simply has to be easier to find chainrings smaller than 30/28 teeth than to swap clusters or individual cogs on cassettes on a ride by ride basis. Chainrings are available down to 24 teeth IIRC. Same advice for the second poster. Rather than fighting to locate old style 5sp freewheels with odd sized cogs what about trying to find a triple chainwheel adapter to allow the use of granny size chainwheels?

H