Re: New Bike

[Ben Barkow <dr.ben@xxxxxxxxx>]

>> Earles forks qualify on 1200s or fantasy bike?
> 
>> Try as I might ot to stuck in the olden tymes, I can't shake the idea that
> the Earles forks design is still pretty good, at least if it was made with
> lightweight modern materials.
> 
> Still too heavy.  It is a good design.  It was designed for use on sidecar
> rigs and works very well for that.  Also happens to resist brake dive, but
> telelever is better for bumpy curves and such.   If you've had the pieces of
> one out of the bike, you know they're not that heavy and the position of them
> minimizes their effect on unsprung weight.
> 
> 
> No sliding bearings. No complicated girders.
> No dampers squeezed into stanchions. No telescopic joints. No
> plastic-covered balls holding everything in place....
> 
> Well, I'm not sure about all that.   Certainly there are damper and telescopic
> joints.  Girders too, just what do you consider complicated?   The telelever
> system doesn't seem complicated to me.   It allows a pretty standard monoshock
> to be used for damping on the front, which is a lot nicer than fork tubes for
> adjustment and servicing.
> 
> At first look, the Telelever seemed to me a crazy and complex compromise of
> sporty/telescopic design motives and something working sort of like a poor
> person's Earles. But experience has shown, I think, that the lunatic
> replacement of tapered bearings (Earles) with a ball joint and bearings
> (Telelever) is durable if still strange.
> 
> Tapered bearings are really expensive to produce consistently.  I've never
> heard of a failure of that ball joint in spite of all the talk lately of how
> flimsy it is.   Although telelever is a little complex, mechanically, it's not
> difficult to produce or service and it's got a lot going for it in terms of
> giving the front suspension better leverage and strength.
> 
>> I find the Telelever works pretty good and possibly has some benefits in
> terms of steering geometry over bumps over the old Earles.
> 
> Yup.
> 
>> While I haven't had a close look at the girder-like fork on the new Ks, it
> may be a really swell design, capturing much of the Earles advantage at the
> cost of ocmplexity and bad looks.
> 
> I think it will work well, but even BMW doesn't consider it an improvement
> over the telelever design.  They feel it is limited because it only allows
> about 5 inches of suspension travel.   That's enough for a sport bike, but
> this system won't work on RTs and GSs.
> 
>> I hope I'm not just fixated on an old puppy-love bike. That puppy love
> lasted 32 seasons as a daily ride.
> 
> Uhhh, OK, Ben.   Save your sweet nothings for the garage.  This is a family
> mail list!  
- ---- Tom Brown

Not exactly right, Tom. You should have have looked at a picture of Earles
forks before writing (pssst... no telescopic joint on 'em....).

And contrary to your put-down, there's nothing sidecar-ish about Earles
except that it is trivial to design an Earles fork with choices of bearing
point to vary the geometry if you need a sidecar, straight-line tourer
(helps if you dose off on long trips or even just to give two-hand waves),
or canyon-carver. The U can be as long or short as the designer pleases with
resulting consequences for handling. Anybody remember the Greeves ISDT dirt
bike with Earles forks?

The unsprung part of Earles (or leading links) forks is just the U-form that
holds the axle and that can be quite light (well, I am ignoring the weight
of the plunger in the shock, some part of the spring, a few fairly light
pieces....). In fact, with the structural benefits of attaching the brake
calipers to that U piece, some weight savings and braking improvement might
be possible.

Earles have greater "sprung" weight. But that could be improved and, in any
case, it not as crucial as unsprung weight.

You aren't quite right about kind-of "resists" brake dive. With a leading
link, you tend to remain level under all levels of braking because the
forces counter-act in proportion. Unless you rely on dive to help you sense
the degree of braking (as some racers claim), there is no benefit to diving.
The Telelever seems to dive some. The Telelevers dive less than telescopic
(and have a vastly less travel... not an all bad thing) But I hope some kind
soul will explain to me how that is inherent in the geometry.

The Telelever uses a single spring/shock unit and that certainly is a major
saving. But /2s were famous for riding around OK with shot shocks on one
side of the front or rear. Now that's what I call proper redundancy.

Ben

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