This is a shot of the bent just after its first test ride, which was a complete success.  As mine was ready to test ride a little earlier than his, he quickly learned how to ride mine.  When his was ready, he got on it and rode off.  Worked like a charm.  The seat is the same one that was on mine (complete with seat fabric repairs :)) as I decided to give it to him because it felt a little too short in the mid-back section for me.  I'll build a new one that is slightly longer and should fit me better.  As it sits in the picture, it weighs 27lbs.  It's missing front brakes, gear shifters, brake levers, small handle bars of some type (undecided as of yet) and most likely fenders.  We were discussing some form of either fibreglass or CF front guard/fender.  Water bottle mount(s) and some form of saddle bags/tailbox would also likely be added.

     It's a little shorter and definitely lighter than mine, and he said his was a little easier and smoother to ride.  It might be due to the slightly different ergonomics, due to the fact he isn't stretching as much to ride this one, or maybe just owner pride :) Either way, it's rideable, and that's the point.

     The front end is made out of essentially the same material as mine.  2" x ½" x .064" steel box tube with a scavenged MTB BB, and an old kid's bike BB for the pivot.  His front section is a bit "cleaner" because he has fewer sections and he angled the front half of the chain stays down a few degrees to keep his BB lower.  It's also a little shorter than mine as he wanted to keep the front end as short as possible because his inseam isn't as long as mine.  He also wanted to keep it as short as possible without causing too many chain-line issues and he succeeded except for not being able to be on the big ring on the front and big cog on the back at the same time.  Minor, as he rarely rides in those ranges on the road, and he is more than experienced enough to manage that small problem with proper gear selection.  Even with all his efforts, he was still fairly tight on the inseam length and had wheel size, crank length and front derailleur/tire clearance issues to juggle.  In the end, he went with an E-type front derailleur that mounts on his BB instead of the derailleur post, so he could cut the post down very low, and that solved one issue.  With the E-type derailleurs, you are limited to about 42 teeth on the big ring, but the 152mm cranks he's going to use are 24/34/42 so that solves both his crank length and chainring size issues in one shot.  That also gives him an extra inch of inseam clearance by changing to the 152's instead of the 175's which are on it now, so that means he doesn't need to switch to a 24" front wheel.

     The front derailleur cable runs down just behind the BB shell, in between the chain stays, and will route along the bottom left and run back to the handle bars.  He has a 9 spd direct mount XT derailleur mounted on the bottom of the chainstays, with the drop outs on top and a SRAM 9spd 11-34 cassette.  His reason for a top mount was to keep the chainstays, and in turn, the BB, low.  He is undecided on where he wants to mount the front brake yet and claims "brakes are only for people who are afraid of vicious wipe-outs".  He's an animal :)

     I think the pivot deserves a little explanation as it is a unique application of a BB.  Certainly one I would never have considered or attempted.  First, he used a complete BB and shell off of a kids bike that had a one piece crank.  After cutting all the tubes off the BB shell, he then cut the crank arms off and left stubs sticking out.

     He started by welding the crank (#1) into a hole in a piece of 3/16" mild steel (#2) that is about 1¼" wide x 2" long.  Then, he welded steel flat stock (#2) to the top of a piece of 1" CroMo bike tube (#3) and drilled a 3/8" hole in the top of the plate that was in line with the center of the CroMo tube.  The CroMo tube is welded at a 70 degree angle to another piece of 1" bike tube that forms the backbone of the frame and runs back to the rear wheel.  Another identical piece of steel flatstock (#4) has a ~3/4" hole drilled near one end for the other end of the BB to go through, and the plate has a 3/8" hole drilled near the other end that lines up with the center of the bike tube (#3) and the hole in the top plate.  There is a small section of bike tube welded to the top of the lower plate (#4) that slides up inside the 70 degree angle bike tube (#3) that acts as a stiffener and guide and stops the bottom plate from moving.  Once the bottom plate is slide into the end of the angled pipe, and over the end of the BB, the BB nut secures one end of the plate, and a long 3/8" bolt squeezes the other end together, and makes a very rigid pivot assembly riding on ball bearings.  He added a gusset on the bottom rear of the pivot assembly to help strengthen the joint.  In the end, the complete front end can be removed by undoing the BB nut on the bottom, and the 3/8" nut on the bottom, the bottom plate slides down and off, and you can remove the front.

     The seat mount is simple 1" x 1/8" steel tabs and has no adjustment as it was built only for him.

14 Jan 06

     We took an old skate blade and made a T-mount that slides into the dropouts, with a stabilizing tube going forward and bolting to the rear brake mount hole.  The main down tube is made of 1" box, with a hollow axle welded to the top of it and a skewer going through it to mount to the drop outs. The tube running forward to secure the assembly to the brake mount is 3/4" box tube with a small piece of angle iron on the end.  We switched out the 26" wheel and put in a 24" with screws because Marcel was concerned there wouldn't be frame clearance.  We took the opportunity to lower the frame a little so total ground clearance in "ice mode" is about 1.5".  The skate blade pivots up and down so it can compensate for any ice irregularity.  With a 7/16" wrench you can switch between the ice adapter and the standard 26" rear wheel in about 2 minutes.

     On initial testing, the python is rideable but there needs to be more screws in the front tire for better power transfer and higher speed cornering.  Also, we're not sure if a normal grind on the skate blade will bite the ice enough, or whether a sharper 45 or 60 degree point is required.  We'll also make a small adapter to temporarily mount a front rim brake.  We'll do some mods and see what the results are.

6 Feb 06

     I took some final pictures of Marcel's ice python after the ice races on Feb 5th.  Here's a list of the mods that converted it to an ice racer . . .

• 24" front wheel and a 1½" tire was swapped in so there would be frame clearance when the tire had screws in it
• we welded up a 7075 aluminum fender as the tire was NASTY with the original small fibreglass fender and would grab pant legs and thigh skin and tear both out with great ease
• dual front rim brakes were installed in accordance to the ice racing regulations.  One at the front of the wheel behind the BB on the underside of the chainstays, and one at the rear in front of the pivot, on top of the chainstays.
• front derailleur and shifter were removed to save a little weight as he wouldn't get going fast enough to need to change the chainring gearing anyway
• a skate blade mount was built that bolted to the rear brake caliper mount in the forks, and slipped into the dropouts with a quick release.  Marcel could get up enough speed that the blade holder frame would hit the ground while cornering hard with a normal skate blade, so we made a new blade out of steel that was 1" taller than a regular skate blade, and a couple inches shorter.  It also had a fairly aggressive ~60 degree point ground on the blade edge vs the standard skate blade grind.
• lastly, Marcel drilled eighteen 1½" and 1¼" holes in both chainstays to further lighten the python.  I think it looked pretty cool, but more importantly, I was very interested in seeing what effect the holes had on the chainstay stiffness.  After riding it, he said he noticed no difference, but he's a fair bit lighter rider than I am.  I think I'll drill the holes in mine too just to see what happens.  As pictured, with about 200 screws and washers in the tire, the python weighs just under 30 lbs, or about 13.6 kg.

     So, how well did it work?  Well, as you can see in the picture, he appears to be zipping along fairly well as he's setting himself up to go into the corner.  In fact he went extremely well, and generally faster than most of the three wheelers there.  Traction on the front wheel was great and the only problem he had was not being able to get enough bite with his rear blade, even though it had a pretty wicked edge ground on it, and polished with a whet stone.  In the 2 man pursuit races, he got so much speed in his first heat, that the rear end slid out on a corner unfortunately, and he went down.  In the slaloms, his masterful riding control enabled him to whip the python around the cones by sliding out the rear end slightly, and he beat all but the fastest two or three trikes.  In the 10 minute criterium race, he was cruising around, and lapping other riders, and well on his way to a podium finish when one of his tire screws somehow managed to cause a flat and he momentarily lost control and hit the boards pretty hard.  He got right up and back on, and finished out the race on a flat for the last few minutes and still managed a 4th overall (I think).  Overall, it was an amazing effort for such an extreme bent and the biggest part of the success was due to Marcel's riding ability.

     As for the traction issues on the rear end, I think that was due to two reasons.  I think the largest part of the problem is how the python turns.  On a normal bike, the rear wheel gets pulled through the corner and follows a line inside the front wheel's track, and has a fair bit of weight on it - likely close to 50%.  The python rear end doesn't follow, but rather it "turns" through the corner on its own path and as a result, I don't think it puts down nearly the same force as a normally steered bike does.  I know that Marcel and I could easily slide the rear wheel out on dry pavement by turning hard and at speed.  Now take that same force, and try to turn hard with a blade on ice that can chip away under heavy loading, and I think that is part of why the python rear end was weak at fast cornering.  Add to that, the fact that as the ice got chewed up from the racing, the blade was tracking across rough ice on the corners and further minimizing its traction every time it encounterd crossing multiple ice grooves, and it lost even more traction.  Even though the rear end would start sliding, Marcel quickly mastered the art of letting the rear end do a power slide, while he kept the power on and deftly used his left hand as an outrigger on the hard turns.  It was amazing to watch him rip up the corners right on the edge of disaster, lap after lap, after lap :)

     Anyway, the ice python did an excellent job at the ice races, and I think it would definitely be tough to beat on larger tracks with larger radius corners.  In the mean time, it'll get converted back to a "normal" python, and he was talking about possibly selling it.

11 Apr 2006

     A couple weeks ago, Marcel decided to do a few final mods to his python after the ice racing was done.  The old modified BB that was used for the pivot was cut off.  In it's place, a bicycle fork had the legs cut off, the steerer tube shortened, and it was flipped upside down.  The rear frame of the python was welded onto the large section of the steerer tube where the fork legs used to be mounted.  Aluminum race adapters were made to reduce the size of the old pivot shell, down so the bearing cups would fit tight.  The steer tube nuts are mounted upside down, and screwed up from the bottom.   The rear frame was flipped over and a 16" wheel with a 110 psi Maxxis was installed.  With the old pivot being cut off and a 16" wheel being installed, both the wheelbase and the length are smaller now.  The 7075 fender was modified slightly and a 26" disc wheel was mounted with a 1" high pressure tire.  We fabricated a disc caliper mount and routed the cabling through the frame lightening holes back to the seat.  The seat angle was changed and leaned back a little bit more than it was as well.  A handle bar stem was shoved down inside the steerer tube, and the front of the seat mounts to the pinch section where the handle bars would normally go.  The front of the seat is now adjustable fore and aft, and up and down so the seat angle can be changed in conjunction with shortening the rear seat support as well.  New specs are below.

26 July 2006

     A fair amount of time has passed by, and Marcel has done the final, final mods on his python . . . we think.  A few tweaks here and there and he slotted his fender (to be like me, I think :)) for both the weight saving and to reduce the "sail" effect from strong side winds.  He rides it up to 50 km a day on his commute to and from work.  I think it's a great looking bent because it is so "clean" and minimal.  A few shots from different angles.