Project

We had to find solutions on different issues during the design and production.

Frame design

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Folding size
The sample is a classic „Camping” bicycle frame from the late 70’s where the front and rear hub are in different position when folded, which gives inconveniences on transportation.

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Wheel size
The sample bike has too wide frame and fork as supported with 20”x1.75 wheels. The 20”x1.25 size wheels need narrow stance with the same dropout distance.

Frame brake
The belt cannot be taken apart as a chain can, so a frame must be able to accommodate the belt by having an opening in the rear triangle. A separation feature needed in the frame that allows for belt installation.

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Horizontal dropout
A key factor to consider is the need to realign and tension the belt every time when the belt taken off or the rear wheel to be removed.

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Wheel design

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Rim
20” size wheels used for BMX bikes mostly. BMX wheels designed for extreme durability, and equipped with 48 spokes. Urban utility bike needs 32 spokes. 20” rim needed with 32 holes.

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Rear hub

Gates Carbon Drive rear sprocket supports 9 spline mounting. Regular 9 spline hubs not support disk brakes.

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Spoke length

20"x1.25 size rims have 31 mm height, rear hub has 58 mm diameter which requires shorter spokes than average 184 mm.