First Impression: Co-Motion Periscope Quad Convertible (Triplet configuration)

Bowen turned 3 last year, but despite our coaxing, he still hasn't shown much interest in his Strider bike. But more than that, even if he could ride, it would be a while before we could trust him out riding in the streets, touring, or even visiting his friends that way. I'd seriously considered a triplet before, but with another son on the way, we thought hard and went with a custom Co-Motion Convertible Periscope Quad. Since I already had heavy duty tandem wheels from our previous touring tandem, I opted for a custom frame built to take 700c wheels, dual pivot long reach caliper brakes and drum brakes, in case I ever got so crazy as to take a quad up a mountain.
The build job took months, and the fitting to Bowen took weeks. The periscope feature enables kids as short as 4' 2" to ride, but Bowen was still far from that. Co-Motion asked us to work with their local dealer, the Bicycle Outfitter, and they kindly agreed to take on fitting Bowen as a pilot project. Basically, they took an existing crank, got a local machinist to machine off the crank arms, and then attached a second bottom bracket and stoker assembly to the bike, added a backrest with restraining seat belt, and then customized the handlebar assembly for the Bowen. This was serious work. We tried to find SPD shoes that would fit him, but none of them were small enough, so we made do we rat trap pedals.
The tandem handles surprisingly well. I felt a wobble early on, but the shop discovered that it was a loose headset. We took it up and down some twisty roads, and the bike did not display any disconcerting behavior compared to our previous stiff-framed aluminum tandem. What does happen, however, is that the S&S couplers come loose on the bike because of the sheer amount of torsion placed on the joints, so we actually have to check and tighten down the couplers every ride. My previous Co-Motion S&S coupled tandem never exhibited this, so it must be unique to these super long bikes.
The reason we opted for a convertible is that we expect the bike to stay in triplet configuration for a few years until the youngest one gets old enough to move into Bowen's seat, at which point Bowen would have graduated into a seat without a back rest/seat restraint. Then we'll ride it in quad configuration until Bowen graduates onto his own bike. And yes, when the kids are all graduated we can stick the front and back halves of the bike together and ride it as a tandem. The minute Bowen saw the bike he immediately knew which seat was his. After 2 rides, he'd figured out how to get into the seat and his feet into the pedals without assistance. He takes great pleasure in wearing his own cycling gloves, and his helmet, though he still has a hard time getting through 2 days without destroying his sunglasses. He was terrified of descents at first, but now demands that I work harder so the bike goes faster. And in case you're wondering, yes, my wife and I ride the bike together without him, and the bike feels quite a bit lighter, so even though he's maintaining 90rpm with us, his contribution to powering the bike at the moment is negligible.
Yes, the bike is slow. 3% grades feel hard, and 6% grades require we get down to the granny gears (a 24x36, in case you're wondering). The bike is well north of 50 pounds in the triplet configuration. We've not tried for any speed records yet, but it will take descents at speed with no problems. One  bug we had trouble with on the bike was the horizontal water bottle cages: any less than a grippy bottle cage would eject the bottles on a bump, and even with a stainless steel high grip bottle cage, if the bottle wasn't inserted deep into the cage, a bumpy road would still take it out.
Taking and putting the bike back together is also more work than you might expect. Basically, you'd have to remove all the timing chains, which require loosening the eccentrics, derailing the chains and storing them before you could unscrew the couplers. When I stowed it into the Scion xB this weekend for a 3 day trip to Monterey Bay, we could get the bike into the car by removing the captain's seat post, uncoupling the bike, and stowing the 3 pieces vertically with one of the rear seats folded down. It's quite clear that with 2 kids, we're going to have to buy a custom rack for one of our cars.
Time to disassemble: 30 minutes. Time to reassemble: 45 minutes. Aligning the couplers on the big heavy bike is enough work that you have to take extra time to do it right, as well as using the special grease that S&S machine recommends.
All in all, the bike does what it's supposed to. People I know (including some cycling enthusiasts in the bike club) have occasionally complained that their children don't like to spend time outside, or don't want to ride bicycles with them. My impression so far is that if you give your child a chance to spend time with you outdoors, he'd happily take that over almost any other kind of stimulation. However, sour that by trying to make a kid keep up with you, or making yourself bored by having to stay at his pace or constantly worrying about traffic, and it's going to be frustrating for everyone involved.  Tandems, triplets, and quads  are ridiculously expensive and practically impossible to resell, but resolve these problems easily and maximize the chance that your child's association with cycling will be a pleasant one.