Magnum BW Overview
Way back in 1990, the very first GreenSpeed trikes were built with 26” rear wheels. However, we discovered that using a 20” rear wheel had a large number of advantages. Not only was the wheel itself lighter, stronger, and stiffer, but it also fed lower stresses into the frame under cornering, so the whole frame could be made smaller and lighter, giving compounding weight savings. Plus the whole machine could be made more compact, and the performance improved. However, we pondered why the trike with the smaller back wheel was faster when conventional wisdom said the larger wheels rolled easier. Thus we tested a large number of different sized wheels, and were surprised to find that at the same section size, same tire construction, and same pressure, the smaller diameter tires rolled easier! Plus we found that not only did wider tires also roll easier, but the type of tire construction played a far larger role in the comfort of the ride than the diameter of the tires.
So in 1993, we changed over to building all our trikes with 20-inch wheels all around. And then in 2006, we went one step further and produced the GT3 folding trike with 16” wheels, which gave a further benefit in performance.
However, there still are a lot of people who firmly believe that the larger wheels are faster. “If smaller wheels are faster, why don’t racing cyclists use them?” Plus not everyone has the need for speed, and many just ride for exercise and enjoyment. Then there are those who just prefer the LOOK of the larger rear wheel, thus there is a continuous demand for a trike with a large rear wheel. So we thought why not?
Greater Stability with Big Wheels
Normally trikes with large rear wheels are unstable due to problems with rear-wheel flex and rear end instability. Thus we have made special GS rear hubs with a much wider flange spacing than normal, which has resulted in a 26” wheel with more lateral stiffness than a 20” wheel! Plus we have increased the section size of the rear forks. Thus with the longer wheelbase, the Magnum BW is even more stable at high speed than the Magnum SD.
For people who want even larger wheels than 26”, the Magnum BW frame has been built to accept a 29-inch rear wheel. Plus the rear forks are wide enough to accept a 4-inch wide tire, and 4” wide wheels may be fitted, with 20 x 4 on the front, and 24 x 4 on the rear, for use on sand. For use on the sand we recommend the use of an internally geared hub like the Nu Vinci or the Rohloff, and the frame is fitted with Rohloff OEM dropouts and extra cable guides.
Big Wheel and Gearing
The large 26” rear wheel of the Magnum BW has a number of advantages over the 20” of the Magnum SD. Instead of needing the special 52/42/30 crankset of the Magnum SD, the Magnum BW uses the standard Shimano Sora 50/39/30 crankset so replacements will be easy to get. Another advantage is the larger wheel lifts the rear derailleur and chain further from the ground so that the trike is more suited to off-road use. Plus, as the 26” wheel is the most common size bike wheel, there is a greater selection of tires available. Finally, the larger rear wheel just LOOKS better than having the same size wheels all round.
In the interests of saving money, some trikes have twist grip shifters. While this might be OK on an upright bike with horizontal handlebars where one can get one’s thumb and forefingers around them, they are awkward to use on vertical handlebars, where one can only get the two smaller fingers around them. Thus the Magnum BW uses the Shimano DuraAce Bar End shifters which make changing gear easier. Also, the Magnum BW has a special MicroShift front derailleur which only needs ½ the force required by the Shimano Sora F/D. We also found that the 11-speed chains now in common use were only lasting a fraction of the mileage obtained from 9-speed chains, plus the 11-speed gears needed more frequent adjustment. Plus, witnessed by the fact that a number of people are choosing to ride single-speed machines, it was obvious that 11 rear speeds were not needed. Thus the Magnum BW has “only” 27 speeds.
Should this range not be enough for some people, a wide range of additional gears may be fitted, as the Magnum BW has special dropouts and extra cable guides for the German Rohloff 14 speed internally geared hub. The Schlumpf two speed bottom bracket and Nu Vinci infinitely variable hub, as fitted as standard equipment on the Anura IGH, are also popular GreenSpeed fitments, as is the SRAM DualDrive hub which is fitted as standard equipment on the Magnum Hand trike.
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Specifications
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- Frame: 7005 Aluminium with quick release seat and centre fold
- Width: 34″
- Length: 87”
- Height: 31″
- Seat Height: 14 to 18″
- Seat Angle: 30 to 48˚
- Seat Width: 16”
- X-Seam Range: 44-54″
- Ground Clearance: 6″
- Turning Radius: 16’
- Wheelbase: 47″
- Wheels: 20” & 26” box section alloy, eyeleted
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- Tires: 20” & 26” x 2.0” Schwalbe Big Apple
- Gears: 27
- Cranks: Shun 165 mm, 50/39/30t
- Cassette: SRAM 9sp. 11/34
- Derailleur: MircoShift Touring Triple \ Shimano Deore super long cage
- Chain: YBN S9
- Shifters: Shimano DuraAce Bar-end
- Gear Range: 23” to 118”
- Brakes: Sturmey Archer 90mm Drums
- Weight Limit: 350 lbs
- Trike Weight: 44lbs
- Standard Equipment: Rear Mudguard, Safety Flag
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