Gear ratios comparison among tiny wheeled folding bikes

[Amuro Lee]

The gear ratio of A-bike/A-bike Plus:
http://www.a-bike.co.uk/store/specification.php
Gear inches: 6" x 14 ÷ 8 × 35 ÷ 9 = 40.83"
Metres of development: 0.15m x π x 14 ÷ 8 × 35 ÷ 9 = 3.21m
Gain Ratio: 150mm ÷ 2 ÷ 140mm x 14 ÷ 8 × 35 ÷ 9 = 3.65

The gear ratio of A-bike City:
http://www.facebook.com/photo.php?fbid=167674339920769
Gear inches: 8" x 14 ÷ 8 × 33 ÷ 11 = 42"
Metres of development: 0.2m x π x 14 ÷ 8 × 33 ÷ 11 = 3.30m
Gain ratio: 200mm ÷ 2 ÷ 140mm x 14 ÷ 8 × 33 ÷ 11 = 3.75

The gear ratio of Handybike:
http://www.handybike.com/uk/technik.html
Gear inches: 6" x 52 ÷ 7 = 44.57"
Metres of development: 0.15m x π x 52 ÷ 7 = 3.50m
Gain ratio: Unable to calculate due to the unknown crank lenth

The gear ratio of Zerobike:
http://www.zerobike.com
Gear inches: 8" x (34 ÷ 14)² = 47.18"
Metres of development: 0.2m x π x (34 ÷ 14)² = 3.71m
Gain ratio: Unable to calculate due to the unknown crank lenth

The gear ratio of CarryMe SD or CarryMe DS in low gear:
http://www.pacific-cycles.com/product3. ... 2=7&pid=11
Gear inches: 8" x 84 ÷ 14 = 48"
Metres of development: 0.2m x π x 84 ÷ 14 = 3.77m
Gain ratio: 200mm ÷ 2 ÷ 160mm x 84 ÷ 14 = 3.75

The gear ratio of CarryMe DS in high gear:
http://www.pacific-cycles.com/product3. ... 2=7&pid=12
Gear inches: 8" x 84 x 1.65 ÷ 14 = 79.2"
Metres of development: 0.2m x π x 84 x 1.65 ÷ 14 = 6.22m
Gain ratio: 200mm ÷ 2 ÷ 160mm x 84 x 1.65 ÷ 14 = 6.19

The gear ratio of CarryAll:
http://www.pacific-cycles.com/product3. ... 2=7&pid=13
Gear inches: 8" x 64 ÷ 14 = 36.57"
Metres of development: 0.2m x π x 64 ÷ 14 = 2.87m
Gain ratio: 200mm ÷ 2 ÷ 160mm x 64 ÷ 14 = 2.86

The gear ratio of Strida 1, 2, 3, 5 & LT:
http://www.strida.com/en/products/?method=listing&sid=1
Gear inches: 16" x 100 ÷ 30 = 53.33"
Metres of development: 1.185m x 100 ÷ 30 = 3.95m
Gain ratio: 1185mm ÷ π ÷ 2 ÷ 170mm x 100 ÷ 30 = 3.70

The gear ratios of different models of Mini125:
http://www.bikeforums.net/showpost.php? ... stcount=13

References:
http://en.wikipedia.org/wiki/Bicycle_ge ... ring_gears
http://en.wikipedia.org/wiki/Gear_inches
http://en.wikipedia.org/wiki/Gear_inche ... evelopment
http://www.sheldonbrown.com/gain.html

[Francesco]

I got to try the Pacific CarryMe DS this weekend.It is one very nice bike, but looks a little cheap compared to the Bromptons and Dahons that were next to it at the Velo Expodium. The DS bottom bracket is cool; I believe it's a Schlumpf (or a copy) Mountain Speed.