Joined: Apr 2005
Posts: 971
Likes: 401
From: Northern CA
Bikes: Cannondale tandems: '92 Road, '97 Mtn. Mongoose 10.9 Ti, Kelly Deluxe, Tommaso Chorus, Cdale MT2000, Schwinn Deluxe Cruiser, Torker Unicycle, among others.
33.3% better than a triplet! 100% better than a tandem!
I'd be pretty wary of the wheels, given the weight of a quad. Brakes obviously too. Frame flex must be through the roof.
I think the best approach is to buy a fully coupled quad so you have a triplet and a tandem all in one. Just remove the middle sections you don't need. Sure, that entails some logistics, but it could be done. But then again, riding a tandem with such a beefy frame and quad wheels might not be a whole lot of fun.