We did a great climb/ride here in Santa Cruz last weekend, Eureka Canyon, about 3000' over 50 miles. Much of the climb rolls along, with some steep sections that gain a lot of elevation quickly. I noticed in the old gear set-up that our 44 tooth middle chainring gearing was a little tough and wouldn't allow us to spin up the long, steady rises, so I'd be dropping onto the old 28 tooth inner chainring. The 28 gave us plenty of climbing advantage, but the chain was too slack on the smaller rear cogs, so I'd have to jump back and forth between the inner and middle chainrings, with a few gears changed in the rear to hit the sweet spot. PITA.
I decided to switch to a 39 middle chainring and as well, put a brand new 12-28 cassette with closer ratios on the rear; I also swapped the 28 tooth inner for a 26 tooth inner to make up for the loss of our 32 in the rear with the old cassette. Voila. All is nice.
We did a 25 mile ride with about 1800 feet of climbing after work yesterday, and the range was perfect. The 39 allowed us to stay on the middle chainring for much of the medium climb pitches, and we only needed to drop onto our new inner 26 tooth chainring for the steepest pitches. The 26 front / 28 rear is fine for the pitches we hit, a wee bit tougher than our old 28 front / 32 rear, but we handled the increased effort fine.
I run a 39 on my roadbike, so it seemed to make sense that same ring might be nice to try on the tandem. Glad i did the swap. So is my stoker. I guess if we rode mostly flats and rollers, the 44 middle chainring would be just fine, but we're in the midst of one of the loveliest coastal mountian ranges, and I like to climb.
The only downside? The chainrings aren't ramped, so shifting isn't as quick or precise as I'd like. Maybe it's time to move up to ramped 39/55 TA rings.
The Tandem details:
1995 Santana Sovereign. 8 speed Sach Ergo shifters with Shimano spacing.
Rear: Changed from 12-32 to a 12-28 XTR 8 speed cassette
Front: Changed 54/44/28 to 54/39/26