So, here are the things in the on-line copy that didn’t resonate with me and challenged my understanding of the pros and cons of the Gates Carbon Drive sync belt for tandems, starting with the ‘better’ gearing system, which reads:
Better gearing system
As for gearing range and shifting, the V2r again excels. The combination of 2X10 road and MTB gearing provides the same wide range as a conventional triple-chain-ring road setup. With a 39/53 double sprocket in front and 11X36 cassette in back (as shown in the photos), the gear range is identical to a road 30/39/53 triple crank with an 11X28 cassette—certainly enough for most any tandem team interested in racing or fast sport riding, for sure. And, with a double sprocket in front, the shifting precision is as good as any single bike, and any road shifter compatible with a matching MTB rear derailleur and cassette will work (SRAM™ Red™ Double Tap™ shifters, Red™ front deraiiluer, SRAM™ XX™ cassette and XX™ rear derailleur shown). Say goodbye to triple front shifters and substandard front shifting!
As I mentioned earlier, for high-performance teams who ride tight ratio cassettes like an 11-23, the right side drive V2r makes sense and would be an attractive package. In fact, I just ran the numbers on the gear inches and was pretty surprised at how closely they did match up to the 11x28t triple… OK, I was REALLY surprised. So surprised that I’ve actually re-visited this blog entry and made some changes and I must thank Terry Malouf who is one of the owners of the first Paketa V2r for responding and making me do a re-read of what I wrote. However, that said, I still believe that for more average fast recreational / sport teams who must deal with any steep stuff, those folks will really need to be really honest with themselves regarding their current gearing: could they really live with just a 30x28t. If so, this might be a good option. However, if they ever needed something shorter than a 28″ gear… noting that a 30x32t granny yields a 24.9″ gear and a 30x34t granny yields a 23.3″ gear, they could find themselves walking a few hills.
Let’s take a closer look at the Paketa 2×10 scenario that saves 1lb: “With a 39/53 double sprocket in front and 11X36 cassette in back, the gear range is identical to a road 30/39/53 triple crank with an 11X28 cassette“. Here’s how those two different cassettes stack-up:
(Click HERE to see graphic stack-up of gear inch comparison)
This is what you give up…11-28: 11-12-13-14-15-17-19-21-24-28
And this is what you get…11-36: 11-13-15-17-19-21-24-28-32-36
Again, potential buyers really need to be sure they can deal with whatever length and grade climbs they expect to encounter with nothing larger than what they could have handled with a 53/39/30t triple and an 11x28t cassette. Most tandems these days tend to come with an 11x34t cassette, which is a very different animal than an 11x28t.
For reference, we’re hardly elite racers but we do tend to fall into the demographic that does the suggested fast sport riding and rides higher-end performance tandems. Here’s our “normal” gearing for hilly but not the really steep stuff… a very nice progression:
Pending release of the 11x32t Shimano CS-M771 cassette, the first cassette listed below (an 11x32t 9 speed) is our current ‘alpine’ gearing. It’s less than ideal with that awkward 18 to 21t jump that we have to deal with a lot on moderately long or steep climbs. Thankfully, the 11X32 CS-M771 will beak that up a bit. Again, here’s how all these different cassettes stack-up:
11-32: 11-12-14-16-18- 21 – 24 – 28-32
Compact drives and doubles have not been the hot ticket for tandems, heretofore. Now, as is always the way with bicycles, with Shimano & SRAM’s introduction of 2×10 systems for off-road bikes they’ll likely become more common, just as compact drive did for the road and 29′er bikes for off-road. So, perhaps 2×10 drives on road tandems are inevitable. However, there are limits to just how flexible a 2×10 drive train can be, and therein lies the problem with the marketing spin: it’s trying to over-reach and make a credible product offering appealing to consumers under the allure of ‘lighter weight and better shifting‘ who may not be well-served by that product over the long-haul. Obviously, the V2r can always be fitted with a crossover crankset that would allow for the use of a triple, so it doesn’t lock in an owner to the right-side drive / double chain ring configuration.
What sticks in the back of my mind is, it’s been my observation that the stronger tandem teams of median income will have only one tandem they use for everything vs. a dedicated race machine, and they still keep that granny gear on the bike with their 11x23t or 11x25t cassettes for use as a ‘bail-out’ gear when they find themselves on those longish double-digit grades or run into a wall while touring or attending a rally away from their normal terrain. Yes, we’ve seen one or two teams with older Santana Team tandems from the 90′s that had DuraAce doubles or somewhat newer tandems with unused granny gears hammering up some 18-20% grades, but they’re the exception and not the rule. However, I’m not sure they’d have been willing to give up their closer ratio cassettes for what the 11×36 offers. But, to be fair, that’s just a guess since none of these teams were all that concerned about or giving up much in the way of their dominating performance as they rode their 40lb tandems up those walls vs. mere mortals with deeper pockets who struggled up using the granny rings and the largest sprocket they had on the newer 30 lb lightweights and exotics.
It’s also worth noting that another tandem builder has been dangling a compact 11x36t drive train set-up with a Di2 option out there for 2-years or so. It would be interesting to know how many of those have been sold and what folks think of them, as well as how they’re being used since that is fairly important too. For example, I ride a compact drive on my single (50/36) and it’s great, but… not sure I’d want to use it on the tandem where we live and ride. You give up a lot of useful gear range that, while you don’t use it a lot on the tandem, you appreciate that it’s there for those infrequent occasions when you want to spin-out that 53/11 gear (and it happens a lot sooner in a 50/11) or you hit a wall that you just rather not grind-out standing on the pedals at 50 rpm.
Finally, I still don’t get the spin on “Say goodbye to triple front shifters and substandard front shifting!”. It must be a Shimano STI thing, as I just don’t hear of folks who use bar-ends or Campy Ergo having front shifting problems, except where their technique is all screwed-up, i.e., trying to shift under load and way too late. Well, and then there’s always the problem where so few mechanics know how to work on tandems, which also leads to problems. But I digress.