MnHPVA Meeting
October 9th 2002
Meeting Report: Tim Dunsworth (with comments by Mark Stonich)
Photos: Mark Stonich
Show-N-Tell
Click thumbnails to read details and see more and larger images.
Another good sized crowd showed up (20+ ?), and as usual we spent the first hour or so out in the parking lot looking at bikes and trying them out. Jon Nygren showed up towing a trailer with two street streamliners in it, and Ray Allison came in a little Honda CRX with a looong homebuilt roof rack to hold an equally long and homebuilt recumbent tandem (more on these later). Eventually we did go inside and started a slightly more formal show-and-tell.

Terry Osell's Latest 'Bent

John Nygren's StreetLiners

Ray Allison's USS LWB Tandem
Lance Oberg passed around several maps from the trip he recently took around southern Germany with his wife Linda. They rode their Rans Screamer fitted with S&S couplings so can be broken down for airline travel. They had a great time, and he liked the fact that Germany often has small towns spaced only 5-10 km apart so a break (ie. a gasthaus with good beer!) is never far away. They rode 18 days for a total of about 1,100 km with only one seriously rainy day in late August/early September.

Dave Siskind's Book & Bike

Tim Fairbanks' modified Haluzak
Technical Mumbo-Jumbo By Mark Stonich

When designing an SWB (Short Wheelbase) recumbent I believe you should always try to get the weight as far back as possible. However, that doesn't mean that getting the rider back is going to improve the handling of an existing SWB, especially one with USS (underseat steering).

Tim Fairbanks' Haluzak is set up with the rider fairly far forward, giving it less than optimum (but not “unicycle with a training wheel”) weight distribution. When I pointed this out, he said he tried it with the seat and cranks further back but handling was worse.

Two possible explainations.
A. With a fixed steering pivot location, moving the rider back might have put him too far from the steering mechanism. Either giving him too much tiller, or putting the grips too far from his shoulders. This is primarily a problem with USS as most ASS SWB recumbents (except LowRacers) would be more stable with added tiller.
B. More likely, the problem stems from the suspension fork. My guess is that the spring rate is high enough that, without a fairly good static load, the fork is only active on good sized bumps, and may be topping out. With Tim over the front wheel, the fork may always be active so the front wheel stays on the ground better.

This suggests two things
1. With their short, steep forks, SWBs have a lot to gain from suspension.
2. Spring rates and/or preload should be carefully chosen to allow static sag for active suspension.


Jeff Caswell's Battle Mountain Report

Mark Stonich's
Wedgie

Tall Dave's
Corroplast
Fairing
Denis Diekhoff is still fiddling with coaster brake hubs, with an eye toward using them on the front of a tadpole trike. He showed a proof of concept rig (Sorry Denis, the photo was NG. Mark)consisting of just a front fork and handlebar to hold a wheel with a coaster brake hub. So far it hasn't worked well, since a hand lever doesn't give the right combination of cable travel and force to make it work right. (Could the problem be that fingers aren't as strong as legs? Mark)

He is using a cast aluminum wheel with Suntour brake internals (the best he has found so far in other respects). There was little consensus among the gang about how much input force a coaster brake really needs, so Denis will just have to keep experimenting and settle the question.


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