Davet's post on Independent Coasting

[Barnaby]

I have noticed that this post is 10 days old and nobody has responded to it. It must be a hot topic in the tandem community, as to whether the different system for cranks is worth the bother. I am considering a new tandem also, and this topic is interesting to me as well. Any takers?

[Davet]

Barnaby: The reason for the enquiry about independent coasting was that I was considering a DaVinci tandem, among others. I called DaVinci (buncha neat guys) and got a very good explanation about their system. 5 large was a bit much to spend on our first tandem though, so I found a screaming deal on a Burley Rivazza and bought it. One of the major reasons for looking into the independent coasting is that my wife and I are very different types of riders and I thought it might be to our advantage. We rode a standard system tandem last weekend and the 'problems' seemed to fade as we gathered experience. The people I've talk to love whatever system they have on their bikes, so I suppose it's primarily a matter of personal preference.

Our new Burley arrives Tuesday, and I'm havin' more dang fun just thinking about it!

[Barnaby]

Thanks for the reply Davet. I have been considering tandems since I came back from a trip with a buddy from Manitoba to Mexico in '79 on single bikes. When my wife and I tour though the pace is different, so I have always thought that the tandem would eliminate the space, either that or I would have to attach a rope to the back of my road bike. This is not really a chauvinistic comment as I am sure that there are many women who could tow me as well, but whereas I could keep pace with my friend, if I ride my wife's pace it really becomes impossible.
A few years ago, I was in one of those rides for multiple Schlerosis on my road bike and a couple from the U.S. passed me by one km. before a fairly steep set of hills here in the Riding Mountains. I thought, with what I have heard about the disadvantage of climbing with tandems, that I woud be seeing them again soon! No such thing happened. I thought that I was fairly good in the hills and since then have re-evaluated the idea of tandeming.
I hope you enjoy your Burley, my jaw dropped when you mentionded 5 large for the DaVinci. My mind reels doing the conversion, but in Canadian dollars, I think with duty and tax that would be around $8,500 on my doorstep. I don't think my house is worth that!
Anyway, good luck on your travels, and let us know how you like the Burley.

[bentbaggerlen]

I have ridden both of the IPS systems on both upright tandems and recumbent tandems, given the choice I would get the DiVinci system for the wider gear range. I did find that I lost a lot of feel for what my stoker was doing on the back of the bike. The Vision system works but looks clunky to me.

Now if I had a few bucks The FS DiVinci off road tandem....

[Davet]

I considered the DaVinci system for the staggering amount of gearing choices, but one of the things that bugged me about Independent Coasting was the one more complexity in between the Captain/Stoker and getting pedals correct for sharper turns.
Nothing againstDaVinci at all. I found the fellow the I spoke to, to be very helpful and forthright. I was surprised to find that there are only three people at DaVinci. They build about 100 bikes a year.

[Michel Gagnon]

I don't have a tandem yet, but I have studied the question a bit.

Advantages

It's easier to start at intersections, because both partners don't need to synchronise their starts.

One of the partners can coast, lift their butt, scratch their leg... without permission from the other person.

If you had problems deciding whether you want to go in synch or out of phase, you now can have your cake and eat it too.


Drawbacks

As someone said, a bit more complex drivetrain, which also means a bit more weight and many more moving parts.

The "chainwheels" are half the regular size. So instead of having, say, 22-36-48 chainwheels, there is 11-18-24. It's easier to get a wide-range drivetrain without going above the derailleur capacity, but it also means more wear on the cogs... especially in winter.

For offroad riding, some people complain that it's easier to scratch the stoker's pedals with the independant pedalling system than with a traditional system.

Regards,

[Davet]

Getting the Stoker in synch with the Captain during turns is one of the things I didn't care about the DaVinci. One thing I did like about the DaVinci is that they use 4 chainrings that are half the size of conventional chainrings. The shifting should be much easier. And because of the double rotation of the intermediate shaft, the 12-18-24-30 chainrings equal 24-36-48-60 tooth chainrings. That gear range is phenominal, 18 to 140 gear inches. That thing has to scream downhill!

It's really too bad that I didn't get to spend time on a DaVince to see if we could get along with it. I'm sure it is a wonderful machine

[Barnaby]

Since discouvering this forum, I have found some very good information. Two things that hit me about tandeming:
1-How to get the stoker enough top tube length to be able to stay in the drops if he/she is so inclined, without your nose being in the small of the captain's back.
2-The independent aspect to Independent Coasting that I think, along with the longer top tube in the rear, would make the set-up mimic the joining of two single bikes, rather than a dominant/reactive set-up that the traditional tandem seems to offer.
The comments on gearing as well are interesting. On my long neglected racing bike, I have only recently concentrated on gearing and many gear changes with the shifters on the down tube. I have found that that old school system is really not too bad, if you elect the drop position rather than the top of the hoods riding position for instance.
As far as gear selection, I can see the attractiveness of the single-step cog relationship. I used to use 13-24 on my 5-gear freewheel, since I moved to a hilly area, with a 49/53 chainwheel set. Since then I found an old 6-speed cog with 12,13,14,15,17 and 19. My cadence really improved with the drop positioning on the old freewheel, and to keep that I find I have to work like hell even on the flats with the new cog, but the smoother shifting is a new discovery. I haven't used the 49/19 on the more severe hills yet, but the way I think it will work is changing the climbing technique to more standing and a slower cadence, which may be OK for hills of this length. I suspect that what may be best would be to consign the largest cog to a granny cog for hills only of 23 or 24 teeth, and then to cash in the racing/wind cog 12 for a 16 or 18. The granny chainwheel that I have on my touring bike is hardly ever used, and means that the chain has to be longer and heavier; and the bottom bracket has to be longer, so more flex dispite the fact that the 3rd chainwheel is hardly ever used. I wonder, with the 10-speed cassettes why you don't just consign a cog or two only for climbing, and enjoy the single-step gears for the benefit of crisper shifting for the rest of the gears. Just musing, inspired by the previous comments about gear advantages.