Another iteration of anti-flop device for S40

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cpml123

Zen MBB Master
Here is my latest iteration of anti-flop device. I have used @tiltmaniac 's version of using big rubber band. I guess I am not flexible enough because I kept tripping over the band. :) Here is the newest version that I just tried. I will have to see how durable it is. It stops the turn at about 50-60 or so degrees. Note this only works with S40 or other frame that has a little screw hole near the fork. I got the springs from Home Depot for about $4.

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cpml123

Zen MBB Master
RojoRacing said:
Needs a shorter spring so it’s under a bit of preload. If only that bolt hole was 2” further back.
Click to expand...
I thought of the same thing too. It's not too bad as the spring stopped the fork from turning at about 50-60 deg. I think as long as it's not 90deg or more, it should be good.
 
billyk

billyk

Guru
I’d be surprised if that worked in the real world. Like @RojoRacing said, you need a LOT more leverage, namely pulling from a distance, and from the side. With that small a moment arm, the spring gets stretched only slightly when the front end is turned. And after a certain amount of turn, you’re not really stretching it any more. Can you walk the bike holding it by the seat back?

The goal is to add little tension for small turns (no effect on steering) but greatly increased tension at large turns.

I made one on my Q559 (now sold) by connecting an old inner tube from the sides of the seat bottom to an eye bolt that extended out back from the fork about 2 inches. That extension increased the moment arm at large rotation, and it worked well for my purpose of not having the fork flop over while walking the bike, lifting it onto a carrier, etc. Moving the pivot point back from the fork also kept the rubber mostly under the seat and not in the way of my feet while getting on and off.
 
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GetBent

Well-Known Member
Interesting.

I have been wondering if it would be possible to put two spiral springs in the head tube with enough tension to cancel wheel flop in each direction. The springs would need to designed such that the spring tension would increase with decreasing turn radius.
 
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