String Trimmer powered bikes (and sidecar)

Discussion in 'Photos & Bicycle Builds' started by Tom Bartlett, Jul 29, 2007.

  1. Tom Bartlett

    Tom Bartlett New Member

    Thanks for the great welcome to a new member. I am attaching photos of a "Zipcycle" , a series of string-trimmer bikes that we built a few years (1994-2004) ago. They were all powered by Homelite (25cc.) string trimmers with a friction roller drive. Now that I am retired I have time to play with a few variations, and I present the first Zipcycle with sidecar, inspired by the recent forum photos of a sidecar for the powered bike. Just a frame now, I plan to add a vintage-appearing body. Notes on sidecar handling: Since I am not exactly a spring chicken, I took it very carefully at first. I went to a local school parking lot,(summer, so it was empty) and practiced first left-hand turns and then right hand turns. I kept increasing the speed until the sidecar lifted. A few more miles, and I began to actually enjoy it (no balancing at parade speeds). Still having fun.
    Tom Bartlett

    Attached Files:

  2. azbill

    azbill Active Member

    nice lookin setup tom :cool:
    does the friction wheel were the tire much?
  3. locoWelder

    locoWelder Guest

    Nice looking ride Tom, dose it have enough tourqe to push two adults?
  4. spunout

    spunout Member

    good lookin' work, tom.
  5. uncle_punk13

    uncle_punk13 Guest

    WOW! Dig that! keep us posted as things progress and adventures are had.
  6. tomcatfranks

    tomcatfranks Guest

    Too kool!! Very vintage-looking, even in this early stage!!!:D:D
  7. Dockspa1

    Dockspa1 Guest

    Hey Tom, looking good. By chance, is that drive roller an ex Boat plug or an old brake stop for roller skates?
    One more question. By looking at the close up shot of the roller, I can't tell if it is mounted with a bearing brace on both ends or not and if not wouldn't that tend to bend the axle especially if hitting bumps?
    You have given me some ideas to try with my little bitty weed whacker motor, so I tap the brain of experience = YOU!
  8. bamabikeguy

    bamabikeguy Active Member

    Zipcycle "Indian" edition


    While you are building your toy, maybe you could fill the forum in on this EXCELLENT example of a Zipcycle. The detail was astounding, even having detail etched through the metal in 4 places I believe.... even the mirror was a class act !!

    I have twenty pix of this bike, after that B'ham News article ran, this fella rode up from Altoona to see if I knew anything about the bike he bought from a friend.

    I am impressed, and when you fill me in with the heritage, I'll tell you how much he paid the guy !!!

    Attached Files:

  9. Tom Bartlett

    Tom Bartlett New Member

    Towards the end of the Zipcycle production cycle (about 2002-2003 or abouts) Murray ceased production of bikes at Lawrenceburg, TN, and opened a plant at Mentachie (spelling?) MS. Basically, they were importing completed painted frames and such from China, and assembling them in MS. Murray's line included one cruiser with retro springer fork, "hairpin" seat, luggage rack, alloy wheels, stainless steel spokes and chain, and the paint shown in your pictures. Zipcycle chose this model as the top of their line, (most others were built on beach cruiser chassis from J&B Importers) but did not build very many. Your pictures show one of the best...I only know the existance of one other, belonging to a collector here in Double Springs. I believe one went to a collector in Sweden, and one to a collector in Japan. I remember asking the Japanese fellow, "Why would you want to ship a bike all the way to Japan?" In barely understandable english, he answered, "Looks very American." Thanks for the pictures. Brings back old memories.
  10. Tom Bartlett

    Tom Bartlett New Member

    Thanks for the questions about the Zipcycle. As for the drive roller, we made extensive tests of every type of roller from knurled aluminum (too abrasive on the rear tire) to modified skateboard wheels. We sent a skateboard wheel off to a chemical lab, and found it was primarily polyurethane. We discovered that polyurethane can be compounded from any Shore Number (an industry measure of hardness) from rock-hard to gummy soft. We tested the Shore hardness of a street tire, and ordered polyurethane rollers that were just slightly harder than the tire compound (this was so that the majority of wear would be on the tire). The result was a roller that gave an excellent grip, but was long wearing. We found we could ride in the rain or morning dew without slipping.
    The driver roller was suspended at both ends by sealed ball bearings. With the 25cc. Homelite string trimmer engine, most bikes would run from 23-25 mph. We experimented with different gearing and found that although we could run a higher gear and obtain slightly higher speeds, the bike had no reserve and the speed fell quickly on hills. So we compromised for a slightly slower speed and moderate hill climbing ability. Basically, the bike was rev-limited at the top end. We advertised a top speed of only 20 mph (that way no one complained). Tom
  11. Dockspa1

    Dockspa1 Guest

    Excellent, and thanks for the response Tom.
    Sounds like in depth home work. Hey, how about impregnated rubber?
  12. beach cruzin

    beach cruzin Guest

    its nice to see the young guys geting into it to :cool:
  13. bamabikeguy

    bamabikeguy Active Member

    Well, when I found out it was worth MILLIONS of potential yen, I decided NOT to tell anybody what he paid, invited him to your part of the country and tell you himself !!

    Lock up the moonshine, Winston County, is on the way !!
  14. srdavo

    srdavo Active Member