How to create a human powered parade float to carry a Hammond organ

Hammond organ being played on a bike trailer We won our first award at The Irish Society St. Patrick Day Parade, March 15 2003.

Ok, so I don't know where the genesis of this idea came from... but Moz and Daniel Kavenaugh are partly to blame... ;-)

Hammond organ being played on a bike trailer

It came up at the beer .sig after a local Linux users' group meeting in Ottawa while talking to MKP after Willy's kernel presentation... We started with back-of-the-napkin calculations to see if it was even feasible with respect to weight, size and power. All three seemed like a challenge -- but within reach. The idea simmered for a while... then came up again after the February meeting... and again after the March meeting.

By this time, we had a week and a half left to do something about it for the St. Patty's Day parade. With SCJody and Vic's help, I started to sketch out a couple of potential designs. I also spoke to Daniel Kavenaugh of Organic Engines and Carey Chen of Urbane Cyclist both on the telephone to pick their brains. Both were very helpful. Daniel helped me with tubing sizes and subsequently sent me an unsolicited but very welcome rough drawing. Juergen and I picked up 4 used heavy duty BMX front wheels at Dave Gibson's Bike Dump, 4 ratchet tie-down straps from Princess Auto, and had a look around Metal Supermarket on Wednesday. Carey sent 8 tyres with Juergen the weekend before that I had not planned to use on the trailer, but it became obvious about Wednesday after construction had started, that I should. I ended up using 4 Tioga Competition Pool 20"x1.75" slick tyres somewhat accidentally and arbitrarily pumped up to 60 PSI. It might have been better to pump them up to 70 or 80 PSI, but it was fine the way they were in terms of a compromise between the negligible rolling resistance they had and the excellent cushioning they provided. These are the same tyres that Ian Sims swears by, pre-installed on all Greenspeed trikes, of which the towing vehicle is one.

I started with the drawings from the pub and drew up a preliminary scale drawing to get a sense of it without having exact dimensions for the organ and MKP was not anywhere near them to measure them himself nor to let me in to do so. MKP and I exchanged email about it which helped, but I wanted to be sure of the dimensions, so I had to wait until the Sunday afternoon when he got back to measure it myself. That resulted in a much more accurate 2nd iteration of the drawing that was used almost exactly.

I made one email order to Metal Supermarket on the Monday at 04:20, less than 3 hours before they openned. After they spent some time converting it from metric to imperial units, I did some serious rethinking of the exact materials since they didn't have enough stock of some of what I requested. Juergen was helpful here since he had experience purchasing and building with that material. I resent my metal list to Adry and Kevin just over 24 hours later.

Juergen and I picked up the CAN$200 worth of cut metal and a new set of UPS batteries on Tuesday afternoon and started building. The pre-cut lengths made things much easier to assemble. Jody and Vic cut the vertical supports and the dropouts. Progress can be seen in the links to photos below.


No, it wasn't powered by a noisy smelly generator like some of the floats were using. That would be a little bit at odds with the theme of "Human Powered Vehicles". It was an industrial grade C-Power Products (Inc., Rockwall, TX) VPS-1500 computer UPS (Uninterruptible Power Supply) with 2 battery packs. Each VPS-BatPak 1500 battery pack contains 7 sealed lead-acid Panasonic LCR127R2P 12-volt, 7.2 ampere-hour batteries making an 84-volt, 16 A DC, 600 watt-hour pack. I ended up using 20A 250V L6-20 twist-lock AC connectors to connect the UPS battery packs in safely, securely and conveniently.

The Hammond C3 draws 72 watts for the organ and preamp. The Leslie 251 amp draws 200 watts plus the tremolo motor draw. There was also a 60 watt lamp inside the organ to keep the tone generator warm. Total draw is estimated at 332 watts.

With these numbers, it should have lasted a little more than 3 hours. Since it was -1C (as opposed to +25C, decreasing the available power) and one set of batteries was not new, it is not surprising that it lasted only 2 hours and 40 minutes.

The Hammond C3 weighs 450 pounds including the foot pedals and bench. The Leslie 251 weighs about 150 pounds. The organist weighs about 150 pounds. The UPS with batteries weighs about 150 pounds. The trailer weighs about 100 pounds. My guess is 1000 pounds total.

About the Leslie, Mark Rehder had this to say:
"The whirling sound is created by the Leslie speaker cabinet. There is a double horn for the high frequencies that literally spins around like a top, throwing the sound around. The woofer is stationary, but has a curved baffle that spins around it, again throwing the sound. Hammonds without this set-up sound pretty flat and monotonous after a while. Modern synthesizers try various tricks to get this sound, and some are close. But the best compromise I've heard is one of the Hammond or Korg organ-synths routed through a small Leslie-style cabinet where at least the top speaker still has some sort of rotational thing happening. You just can't get that sound without resorting to multiple speakers and some kind of surround-sound programming. Even then, it's just not the same thing."

2010-08-08: Richard has just acquired a 1960 Hammond M3 which should fit the front of the trailer.

As a footnote... I bumped into a true human powered organ

There is a group in Boston that have built a large bike trailer that I don't think I would trust with a Hammond organ...

Other missions with the big-ass organ trailer:

Other references:

Please feel welcome to email Richard Guy Briggs for explanations or details of what is documented above.

Page last updated by Richard Guy Briggs Tue Jan 3 15:18:30 EST 2012