Frequently Asked Questions and Answers
about the Shaft Drive Transmission System and Chainless Bicycle
How many different types of shaft drive do you produce?
o Two sizes: (a) 390mm for children's bikes, and (b) 440mm for adult bikes.
o Two different rear-hub gears. The rear-hub gear for single speed is different from that of 3,4,5, and 7 speed, since it has to adapt to the internal hubs.
o The design of the shaft-drive transmission system (SDTS) (e.g. length, gear size, gear housing, etc.) can be modified if quantity warrants.
What are the parts of the shaft drive made from?
o The shaft and gear housings - aluminum alloy
o Bevel gears - chromoly.
o The transmission and crank axles - strong carbon steel alloy (S45C).
What is the gear ratio and resistance level?
o The SDTS gear ratio is 2.077 (one revolution of the pedal turns the rear wheel 2.077 turns).
When coupled with a Sram-Sachs 7-speed internal rear hub, the first gear ratio is 1.2 and the distance it travels is 2.6 meters; the 7th gear ratio is 3.5 and the distance is 7.3 meters.
o In comparison, a 21-speed derailleur system (28/38148:13/15/17119122126132) gear ratio is from 0.9 to 3.7, and travels from 2.0 meters at the lowest gear to 8.2 meters at the highest gear (28" tire).
o SDTS has less loss of power due to better efficiency (99% vs.95%)
How heavy is the drive shaft? How much will it add to the weight of a bicycle?
o SDTS weighs 4.3 lbs. (1 kgF2.2 lbs.)
o A bicycle using cromoly frame and the SDTS weights about 16-17 kgs.
o Presumed efficiency on a high quality chain system for bicycles is 95%. This means that, for a cyclist plus bicycle weighting 95 kgs, the final rated loss of power is 3.0 to 3.5 kgs compared to a shaft/gear bicycle with 17 kgs plus 78 kgs cyclist (same 95 kgs) will have an effective bicycle weight on riding of 13.5 to 14.0 kgs (due to 99/O efficiency) without sacrificing its resistance.
Can existing bikes be retrofitted with SDTS?
o No. SDTS needs a wider and shorter bottom bracket shell and special dropouts. However, once the bicycle frame is built to adopt the SDTS, other bicycle parts can be added to build a dream bicycle.
What are the advantages over the traditional bicycles?
o Safe: no chain to fall off, no chain bite on pants or skirts. - Clean: axles and gears enclosed - no grease/oil exposure.
o Low maintenance: durable bevel gears remain true year in and year out. Quiet and smooth ride: less loss of power due to better efficiency.
o Simple: no complex derailleur/ chainwheels; use internal gear/speed-shifting system.
How many speeds can the bicycle have?
o It has the- capacity for up to 7 speeds.
o SDTS is compatible with brand name rear intrnal hubs - Japan's Shimano, 3, 4 and 7 speeds, England's Sturmey Archer 3 speeds, and SRAM-Sachs' 3,5, and 7 speeds. It uses any one-speed rear hub.
How often do you have to add grease?
o Fill grease in the gearbox after first 500km.
o Thereafter every 4-6 months under normal use.
o Recommend using good quality grease for best performance.
o (or lifetime grease which does not need replacement).
o A cover under the gear housing can be removed for filling grease.
Does your company guarantee quality of the products?
o Yes, we guarantee that all parts of the SDTS and chainless bicycles are free from manufacturing defects for one year.
o SDTS's gears are made from strong alloy and of good quality.
o Under normal use, the gears will not fray for a long time.
o One bicycle to one box: 70% to 95% assembled according to customer's choice.
o Size/dimension: 54'L x 7.5" W x 28.5" H = 6.8 cubic feet.
o Gross weight: 16-19 kgs, depending on model selected.