Re: Getting old is not for sissies

On 3/1/2025 8:06 PM, Frank Krygowski wrote:

On 3/1/2025 4:39 PM, Jeff Liebermann wrote:

On Sat, 1 Mar 2025 13:55:50 -0500, Frank Krygowski
<frkrygow@sbcglobal.net> wrote:
>

IIRC, hydrostatic transmissions are standard features on zero turn
mowers. But as you noted, the mechanical efficiency is lousy. That's not
a concern if you have a big enough engine and low enough use hours. It's
a huge concern for a cyclist.

>
True, but the huge concern is mostly for racing.  If you're using the
bicycle as a moving exercise machine, the added weight and increased
friction might even be considered beneficial.  It's like the weights
on barbells where light weight is not a concern.  For competitive
fixie racing, maybe the governing organization should specify a
minimum allowable bicycle weight, which might inspire technical
innovation instead of shaving grams off the bicycle weight.

>
I think that level of inefficiency would be a concern of most cyclists, and very few actually race. It would take a lot of fun out of riding.
>
I once worked on a bicycle belonging to a friend that had a quite rare (at least, at the time) 5 speed Sturmey- Archer geared hub. IIRC, there were two shift cables, one going to each side. Anyway, as I remember when shifted to its lowest gear it seemed extremely sluggish. Unlike the equivalent low gear on a derailleur bike, it really didn't seem much easier going uphill in that gear. Instead it just seemed slower. And as I recall, that was a not uncommon complaint about that particular hub.
>
I understand the desire for exercise. But I think almost everyone prefers to get their exercise while moving farther or faster, not by slogging along slowly. If that were acceptable, we'd all be riding solid tires.
>
>

 Odd symptom and no logical reason for it IMHO.
 The S-5 gearbox (went through several variants) is basically an AW three speed design with dual sun gears. With no left side change, it's a three speed (+26.6% high, direct drive, -21.1% low).
 When the left side is changed, the sun gear clutch slides over to the other gear set, giving -33.3% super low, direct drive and +50% high.
 The gear sizes being different from an AW (-25% low, direct drive, +33% high), the five model notably gives a faster high gear but not a lower low gear.
 Since everything is in the same oil bath* and rolling on the same bearing adjustment*, overall efficiency should vary only in the relative losses of gear diameter which is a small difference.
  * can be correct or deficient