Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.timo888
11-16-08, 07:02 AM
This morning, before morning coffee while my brain was still in a state of waking dream, I drew up a design for a 16" (ISO 305) folding bike that starts with the Swift. I want it to eat Brompton's cheese sandwich, so symbolically I gave it a wheelbase of 1066 mm (400 rear, 666 front).
The major differences are:
1. The seat-stay pivot-point is moved to a flange behind the seat tube
2. A second pivot point (like a Horst link except not for suspension) is placed on the chain stay in front of the rear axle. The rear-triangle remains unified, but the pivot allows the angle between chain-stay and seat-stay to become more acute, so the chainwheel can be moved further back towards the seat-tube when, during the fold, the rear-triangle is pivoted beneath the main tube. Repositioning the chainwheel aft during the fold allows a hinge to be placed near the front of the main-tube (like Brompton and Peregrine), which significantly reduces the length of the folded package.
Regards
T
The major differences are:
1. The seat-stay pivot-point is moved to a flange behind the seat tube
2. A second pivot point (like a Horst link except not for suspension) is placed on the chain stay in front of the rear axle. The rear-triangle remains unified, but the pivot allows the angle between chain-stay and seat-stay to become more acute, so the chainwheel can be moved further back towards the seat-tube when, during the fold, the rear-triangle is pivoted beneath the main tube. Repositioning the chainwheel aft during the fold allows a hinge to be placed near the front of the main-tube (like Brompton and Peregrine), which significantly reduces the length of the folded package.
Regards
T