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Ice Trike With the ice races in Brantford ON coming up(Feb 5th 2005), a couple of us decided that we'd make an ice racer and go down to it. I had an old frame from an abandoned rear suspension project and decided I'd try to adapt it for ice racing. I did up a 3D version of what I wanted it to basically look like. Low to the deck, fairly wide track, minimalist design (for lightness - which didn't work out :)) and as comfortable and low a seat as possible.
I elected to go with a straight cross member, tilted back at my standard 15 degree angle for a little self-centering. I also decided to go with no king-pin inclination, or center point steering, as I reasoned that on relatively smooth ice, there would be little problem with brake or bump steer. I was planning to use a crankset with 152mm or 160mm cranks on it. I was undecided whether to add a front derailleur post as I wasn't sure if I'd need any more than 5 or 6 gears for any one of the races. At the very least, it could save me precious weight :)
With a flying cross, I designed it to have a little triangulation to try to stiffen up the rear end twisting, as I had a problem with that on a previous trike. The plan was also to add dual V brakes at the rear as dual brakes were a requirement for the ice races.
The blade holders and blades were going to be simplicity itself. I gutted a pair of old men's ice skates and was planning to mount the blades inbetween a couple short pieces of ½" square tubing with 16 gauge walls. I'd add a piece of 3/4" steel tube with 1/8" wall for the blade holder's pivot bolt, and a couple pieces of 1/8" plate to the top to hold the two sides of the blade holder together. I mounted the pivot bolt and housing about an inch aft of center to maybe use the rocker profile of the blade to keep the nose light and reduce the danger of the blade flipping over on rough ice.
The real McCoy The trike build went pretty much as planned. I re-used the old rear suspension frame and added a piece of 1½" steel tube to connect the rear end of the backbone to the front of the chain stays. Added a short piece of 1" tube to both stiffen the rear end and as a mount for the brakes. Minimal chain tubes except where it might hit the cross member, no hand grips, 12" of X-seam adjustment, and a single friction shifter.
At the races, I hadn't coated the frame yet and didn't have the lower pieces of ½" box tube for triangulation because a) I wasn't sure I need them and b) I hate triangulating frame rear ends. I mounted the rear chain pulley (crappy old roller blade wheel) down low and to the rear so that the power side of the chain would clear the lower V-brake. After the race, the chain stays had a slight twist to them because all the racing was counter-clockwise, so I used a special, custom piece of 2 x 4 to straighten them, and then added the ½" steel tube for stiffening. There is no lateral stiffening because the rear guide pulley is bolted tight in between the two pulley mounts and I think they'll act as lower triangulation. I drilled holes in the 1½" steel tube to act as cable guides for both the gear and brake cables to save on having to add cable stays. There are 1" tabs for fender mounts at the rear of the trike to be used for a different fender if my genuine, imitation, plastic CF fender dies. I bought a weird cantilevered Suntour rear derailleur and can't find a twist shifter that it works with, either Shimano or Sram. Regardless of what shifter I use, it always ends up 1 gear shift short for any 6, 7 or 8 speed cassette/freewheel or twist shifter. I set it for the 5 lowest gears on an old steel 6 speed cassette and 26" wheel and used an old plastic friction shifter. Worked fine and I didn't need or miss 6th gear.
I ended up using 160mm cranks with a 39/50 chainring and no front derailleur. For the races I left the chain on the small ring and just shifted at the rear. It has a 115mm threadless BB and basic BMX platform pedals. They worked great and my feet never slipped off once. The kingpins are the same style as the road trikes only I left out the grease nipples. Dual rear view mirrors were a race rule requirement. The handle bars and control arms are made from 3/4" box tube and scrap pieces of 1" stainless tube. I added three 1" tabs to the front to mount a small snow plow to help clear snow off outdoor rinks and tracks. Plow details will be added when I build it.
The blades and blade holders came out pretty much as planned. I had 1/16" flat washers in between the blade holders and the blade when I welded them up. Welding would tighten them up a little, plus the expected powder coating would take up a little more space, so I figured I would need maybe one or two 1/32" shim washers when it was done. It turned out I only needed one shim washer. I used stainless steel bolts, washers and nuts to avoid as much corrosion as possible. I needed to angle the bottom of the steering arms up a little because when I designed the trike, I had them parallel to the ground. When I built it though, I forgot and welded them perpendicular to the kingpins, which gave them a 15 degree angle because of the caster. This put them far too close to the ground, so I notched them and brought them up about ½". The bottom of the skate blades was a standard flat grind and I was hoping that when turning, the steering would angle them enough so that an edge would bite and turn the trike. At the races, this proved to be a bad idea as the edges did not bite enough and the trike pushed really badly in the corners, especially at speed and was therefore very slow in the corners. After the first slalom race I was prepared to sit down in the snow bank and weep bitterly for a couple hours. My friend, who went to the races with me, noticed a man across the street with his garage door open that was making all kinds of "woodworking noises". He ran across and asked if we could borrow his grinder for a few minutes and he agreed. As my tears of defeat transformed into tears of joy, we furiously unbolted the blade holders and ran over to Jack's garage and I proceeded to grind a roughly 45 degree angle point in the middle of the blades. After completing both blades and stopping to thank Jack for the use of his grinder, we quickly bolted them back on in time for the 2nd slalom heat. The steering was awesome but the tiny grooves on the ground blades acted like sandpaper and made it difficult to get the trike broke free. Since then, the grind on the blades has been evened up and polished to a very smooth finish. The blades run fine and still steer great.
A close up of the dual rear V brakes. Tons of stopping power with the screws in the rear tire.
Seat The seat is a slightly modified version of the ones I've built prior. For starters, I decided to try 3/4" EMT instead of the stainless I had been using. Very inexpensive, easy to bend and a little bit lighter. It was very stiff and I'm quite happy with it. The more contoured design is so that the seat can be reclined more and still give enough support for the shoulders so that it doesn't put undue strain on my neck. Wheels The rear tire was initially a Kenda knobby with 1/2" #10 screws. To determine where to drive the screws, I took a small drill bit and drilled through the knobby parts of the thread, from the outside in. This left holes on the inside and I could easily see where to put the screws. Initially after sharpening the blades, there wasn't enough traction. A quick trip to the hardware store between races and we doubled the number of screws in the tire. After that, tons of traction. In fact, TOO much traction. While traction was great at speed, it actually started to slow me down because the screws were too long and causing drag at higher speeds. The solution was to switch to #6 screws that were 3/8" long and had a washer under the heads to shorten them a little bit more. I also decided that seeing as how the screws were giving me the traction and not the tire, I might as well put on a smoother, road tread tire. I had an old Kenda road tire that I drilled the same way, only I drilled EVERY high spot on the tread. Took me about an hour. Then I used the 3/8" screws with washers, that I mentioned, and put 204 of them in the tire. I did a test run and the traction seemed ok, but maybe tomorrow I'll give it a good hard run, or find an arena where I can borrow some ice time and test its cornering at high speed, which is where the traction is needed most. If need be, I could put another 200 screws in the tire. One thing I hadn't anticipated though was exactly how much MORE the screws and washers would add to the weight. For all the weight I saved elsewhere, the tire used that up and then some and the ice trike is one of the heaviest ones I've built yet. Maybe I can shave some weight by going to an aluminum rim.
Misc Hardware The paint job is gloss blue powder coat done by The Finishing Centre. The chain tube is ½" plastic irrigation pipe with flared ends to help guide the chain. The rear fender is a genuine immitation carbon fiber one from the local hardware store. I'll mount a bidon on the handle bar for the races so I can suck back some water during the endurance races :) Specs:
Next time . . .
More trike info as they are built . . . |
