What I ride and why 20" wheels.

Discussion in 'General Questions' started by boyntonstu, Jan 11, 2015.

  1. boyntonstu

    boyntonstu Member

    My friends are avid bicyclists that ride $1,200+ folding bikes.
    The bikes come with 20" wheels.
    I found the bike below for $12.50 at a thrift store.
    After adding a stem extension and raising the seat, I am very satisfied with the results.
    20" wheels are stronger that larger wheels and will resist spoke bending and breaking better than 26" wheels.
    I plan to have another bike with a 80 cc motor mounted in the rear.
    Notice how much room is available.

    My 20 mountin bike (2).JPG My 20 mountin bike (1).JPG

  2. KCvale

    KCvale Motorized Bicycle Vendor

    Nice score.

    Just to be clear, there is no such thing as a Chinese 80cc 2-stroke, they are all ~66cc and ~3HP and should be referred to as such to end the silliness associated with that marketing claims of 4-5HP 80cc BS.

    Anyway, back to the topic of putting a 2-stoke bump start engine on the back of that bike...
    You might want to re-think that as a motorizing option unless you are a skilled welder with engineering skills because you won't be able to mount it to it basic rack, the torque will twist it apart.

    An electric is the best option and lowest center of gravity, but there are little pull start 4-strokes with decent rack mounts that will work.
    I don't mess with those myself but if you don't mind getting a second kickstand or tripod or something to keep it upright when you are not riding it they seem to work well.

    I think a $300 36 or 48V 'water bottle' LI battery and electric shift kit like SBP sells for $400 would be your best option.
    It will use you bikes gears, allow you to pedal with no resistance, and be a very low center of gravity for romping around off-road.
    Just my take.
  3. wheelbender6

    wheelbender6 Well-Known Member

    Many adults that ride on 20inch wheels add riser (ape hanger) handlebars and a banana seat for a more comfortable seating position. Just remember that the smaller wheels can make handling twitchy when your speeds reach and surpass 20mph.
  4. boyntonstu

    boyntonstu Member

    Faster speeds offer more stability on any bike.


    Last edited: Jan 11, 2015
  5. Timbone

    Timbone Active Member

    Bike racers (on the road) are running 700c wheels (~27") because they work best for road races. Tri-guys and some racers will occasionally play with 650c wheels but that is still 26". A 20" wheel is not something we are gonna see in bicycle racing, at least not on the road.
  6. boyntonstu

    boyntonstu Member

    All below are 20" or smaller see photos:


    1985-1986 - In the Autumn of 1985, at the International Human Powered Speed Championships, a fully-faired Moulton ridden by Jim Glover broke the 200 metres flying start speed record, at 50.21mph (80.79kph). Then on August 29th 1986, at the same event, he broke his own record at a speed of 51.29mph (82.54kph) which still stands today for the conventional riding position. The Moulton ridden was an AM SPEED with the fairing designed by Doug Milliken of Buffalo, NY.

    1987-88 - Dave Bogdan rode the ultra-endurance Race Across America (RAAM) in 1987 on a pre-production AM-Jubilee, and in 1988 on a prototype AM SPEED. His 1987 time was 11 days, 8 hours and 2 minutes. In 1988 he improved on this by completing the 3,073m (4,944km) route in 10 days and 15 hours and 1 minute, averaging 289 miles (465 km) per day. He finished 8th out of 35 starters in what is not only the toughest, longest 'single stage' race in the world, but also the ultimate test of man and machine.

    1989- Richard Grisgby of the Bath Cycling Club, riding an AM SPEED, came first out of 180 in the 1990 Fowey Triathlon in Cornwall. He also came third in the cycling split of the Kingswood Triathlon out of some 400 competitors and was only 9 seconds behind a 1st category roadman.

    1991 - Gerry Tatrai wins the 24 hour HPV race around the Milwaukee Mile Track, Wisconsin USA.

    2001 - Dan Farrell (on NS SPEED) completes the world's longest randonnee, the 1400km London-Edinburgh-London in 100 hours.

    2003 - Chloe Williams (on NS SPEED) completes Paris-Brest-Paris, a 1200km randonnee, as youngest female finisher and wins the Audax UK Merit Trophy for most outstanding cycling performance of the year. Dan Farrell rides PBP on prototype TSR.

    2007 - Kazuhiro Yamamoto on a NS Double Pylon finishes 6th out of 320 in a 4 hour solo class at Suzuka, Japan.
  7. Timbone

    Timbone Active Member

    These are specialty endurance events. Not to denigrate them but they are not professional road racers.

    The amateurs are copying the pros, mostly running on cassettes whose biggest gear is 53x11. I have an 11 on my road bike, too, and it is not used very often. It all comes down to math: to win a bike race you gotta outsprint the guy next to you. Running the same gear, I don't want to be turning a 650c when my opponent is turning a bigger 700c because, in order to get a higher top end, I have to spin significantly faster. This is why road racing won't be seeing 20" wheels anytime soon!
  8. boyntonstu

    boyntonstu Member

    Please respond to Park Bikes claim:

    Many folks who remember riding their 20-inch bike chasing an older brother or sister on a larger wheel bike ask the obvious question:

    Don't you have to pedal more?

    The simple answer is, No!

  9. butre

    butre Well-Known Member

    more importantly a 20 inch wheel doesn't hold its momentum for very long. not a big deal for a sprinter trying for land speed records but for an endurance cyclist it makes a huge difference.

    of course if you're putting a motor on it, engines don't get tired.
  10. boyntonstu

    boyntonstu Member

    Are you aware of these endurance records?

  11. SunkyWorks

    SunkyWorks Member

    Thanks for the info Boyntonstu.

    Wide enough 20" rims can mount 16" moped tires rated at 70 mph.

    48 spoke wheels are cheap.
    boyntonstu likes this.
  12. boyntonstu

    boyntonstu Member

    Thank you for something I never knew.

    Have you done it?

    48 spoke wheels are cheap. And strong.

    I would imagine that a 48 large gauge spoke wheel would be quite rugged.
  13. SunkyWorks

    SunkyWorks Member

    This is what I bought:
    Shinko SR714 F/R Moped tire - 2.25L-16/Black
    rated for over 70 mph.

    They fit nice on 20" cheap bmx 48 spoke steel rims, the sides (that contact the brake blocks)
    are more sloped than Aluminum ones.

    Sidewalls are thicker than bike tires, tread not so much.

    I did use some heavier than normal tire irons.
    Last edited: Jan 12, 2015
  14. boyntonstu

    boyntonstu Member

    Wow! Terrific!

    What engine and how is it mounted?

    And, of course, how fast does it go?
  15. SunkyWorks

    SunkyWorks Member

    I bought 4 tires to get free shipping.
    I wanted to mount them to find out if they fit that narrow a rim. I have not run them.
    I weight 230 and am looking for cheap bullet proof wheels.

    Looking to do a rear rack, 35 to 45 mph.
  16. Fly1

    Fly1 Member

    I say go for it.Post pic,s when you finish.
    Cool in deed Fly
  17. SunkyWorks

    SunkyWorks Member

    2" steel rims, 14 mm axle, 12 gauge spokes would be would be bomb proof.
    Used moped wheels might be cheaper and stronger.
  18. wheelbender6

    wheelbender6 Well-Known Member

  19. troyg

    troyg Member

    You need to be careful what type hinge is on a folder you're going to motorize.The above is not what I would use, too much chance of failure with the added stress.Good folder design is "Bike Friday" and my favorite "Raleigh Twenty".