2012 Mongoose Kos Kruiser Tandem 26

Modern twist on a rare classic

In the Spring of 2011 I decided several things.

1. Tandem's serve a great function, but they do have some drawbacks. In my case, the first drawback was that most of them don't fit kids. Second was that I didn't want a road bike tandem, mountain bike tandem, beach cruiser tandem, or any other kind of tandem I'd ever seen other than the 1980's Kos tandem (pictured above - not mine) and the Metal Bikes tandem that Odyssey and Jimmy Levan built for InterBike a few years back.

2. Those two were what I wanted. This decision had a couple of problems associated with it, namely that the likelihood of my getting either one was slim-to-none and even if I did, it still wouldn’t solve the dilemma of kids not being able to ride it.

3. Next I decided that with over 30,000 members on BMX Museum, even if only 0.5-percent of those folks have kids that they want to ride with but aren’t always able to based on factors like destination, route, distance, etc., there’s at least 150 people here who’ve had the same thoughts as me.

4. Those 150 people would have an appreciation for, and possible desire to purchase, a tandem that checked the right boxes.

5. If the emotional connection to bikes that allow us to remember our youth is enough to get folks to cough up nearly 2 Grand for a pair of cranks that some factory guys couldn’t be paid to ride, and sharing that connection with your kids creates a stronger family bond, then building this bike is not insane.

You on the other hand, may just have a hot girlfriend who doesn’t know how to ride a bike. Either way, this bike had to be built.

In case you’re staring at the bizarre drivetrain, I can explain. The lower rear BB shell uses an eccentric BB, which allows the upper and lower rear BB’s to have proper chain tension. The “floating” chainring creates tension between the lower front and rear BB’s. The idea with this set-up is that, with small kids you install the rear pedals on the upper cranks, and with anyone bigger, you run it like a standard tandem, and and install the pedals on the lower crankset.

Here’s a list of answers to questions I know will be asked of me:

Q: Are you insane?
A: Aren’t we all?

Q: Do you work for Mongoose?
A: Maybe. If you want one for free, then no, I don’t.

Q: Is this a production bike?
A: Unfortunately not.

Q: Are you insane?
A: Me? Didn’t you just ask me that like 20 seconds ago?

Q: Can you build me one?
A: Maybe. Go find 50 of your closest pals who are willing to buy it 12+ months in advance of production. Do it now.

Q: How much would it cost?
A: More than a NOS set of full-wrap single-pinch Flights, and less than three pairs of NOS magnesium Motomags.

Q: What age range is the rear designed to fit?
A: From your 5-year old to his Great-Grandma.

Q: Are you insane?
A: Do you have a concussion or something?

A few more Kos friends in my bike family:

Trans-Am-inspired Metallic Brown Kos Krusier

V1 Prototype Kos Kruiser

Kid Kruiser

White Kos Kruiser

Last edited by bmxmarty (2022-10-03 11:34am)