Hi Michael,
The rule (in part) doesn't say vertical travel, it says front wheel travel, so it should be as simple as putting a zip tie on the fork leg and giving it a good bounce.
An easy response to that is "front wheel travel in what direction?" Horizontally, vertically, along the steering axis? If the latter than what about Bultacos that have the forks angled differently from the steering axis?
Teleforks generally get defined by actual telescopic travel. But a telefork at a steeper rake is going to have a larger amount of vertical travel and might be able to absorb a larger bump with it. A telefork with the same stroke on your typical chopper (or raked out Triumph desert sled) won't be able to deal with that bump as well because the wheel movement is more rearwards than vertical.
Rear suspension appears to usually be defined by the rules in various organizations by vertical travel. The actual amount of wheel-path travel for a given vertical dimension on a swing arm suspension will vary with the relative height of the swing arm pivot. A LLF is more like the rear suspension (both use swing arms) than it is a telefork, so it could be sensible to also measure the travel vertically. I presume there is a desire to be consistent and not comparing apples and oranges, but that could be a presumptious assumption.
Shucks, you could even say that teleforks are defined by actual damper travel, so if that is the way the rule is worded any LLF that had less than 7" of travel
in the damper should be legal, no matter what the wheel travel might be.
I can put a zip tie on the stanchion of a Greeves LLF and bounce the front end and the zip tie won't move at all. Or I can put it on the damper shaft and say "see, I've got another 3 inches I can add before not being legal".
Words mean things, so you have to be careful how you use them. A rule that depends on poorly defined terms may find itself being challenged with a "what does that actually mean?" question.
If front wheel travel is meant to be measured in a straight line between full bump/full droop axle positions then the rule ought to say that, especially when there are 10-20 years of bikes out there that didn't use teleforks (DOT, Cotton, Greeves, Van Tech, Sachs/DKW/Hercules, Reynolds, some works BSAs and Husqvarnas. Scorpion, Butler, Sprite, Tandon, Royal Enfield, Maico, Tandon, DMW, Cheney, Rickman etc just to name some that I found in reference books with a couple of minutes of page-turning). If the actual distance traveled by the axle (which means along the arc, not the chord, for a swing arm) is what is wanted, the rule should say that.
As I think I said earlier, I think most people are willing to accept a range of rules as long as they sound somewhat reasonable and aren't ambiguous. But at times it can take a bit of thinking to eliminate ambiguity.
My dealings with AHRMA rules leads me to believe that many times the rules are done by people of good will who are fairly expert in the field, but while their expertise may be deep the breadth of their knowledge is just a bit too limited. That can lead to a perfectly sound (but limited scope) rule that fails as soon as someone pipes up with "but what about all of these bikes where that doesn't work?" If they've got zero experience with anything but teleforks, the possibility of making sure that the rule covers leading link/trailing link/girder/who knows what? front ends may never even occur to the rule makers.
I've got/had both Hercules and Greeves LLFs, I've got lots of photos and I can make replicas of Van TechReynolds etc forks and I'd like to run a LLF on some project bikes because I think they are cool and teleforks are kind of dumb.
So I contacted my local rule makers and asked "how do you want to measure the travel of this fork because the rule book doesn't really apply to it and I don't want to show up and have someone hassle me over "too much travel"." When I can't get an answer it makes me a little uneasy. I'm not looking for any particular answer, but if they can't pick one of three obvious alternatives, what are they doing on a national rules committee?
cheers,
Michael
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