faq 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. Bicycle Packaging: 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.