Re: [CR]Hetchins Build / Effective wrap diameter of some shifters


Example: Racing:Jacques Boyer

Date: Sun, 24 Oct 2004 18:03:18 -0700 (PDT)
From: r cielec <teaat4p@yahoo.com>
Subject: Re: [CR]Hetchins Build / Effective wrap diameter of some shifters
To: classicrendezvous@bikelist.org
In-Reply-To: <417C48F2.8010409@erols.com>


Ahoy !

Firstly, to avoid any misunderstands, I will say this is a legit. straight forward inquiry; not being critical nor wise-cracking. I respect and appreciate Harvey's desire to get it right the first time. Don't we all?

I've been following the discussion and am a bit puzzled. That is, in my naivety, I don't understand the fretting over matching levers and derailleur. I'm thinking: this is a friction installation; universal interchangeability, that's a great advantage with friction; any levers work with any derailleur (some odd exceptions I'm sure; and, of course a quality factor). There's all this scrutiny of compatibility yet, cable stretch or a stop one or two millimeters removed could affect shifting.

Can someone explain the need for such thorough technical analysis of matching levers to derailleurs? I didn't think it was such a critical process.

Thanks.

Richard Cielec Chicago, Illinois

HM & SS Sachs <sachs@erols.com> wrote: My quest for guidance on the Hetchins drive train clearly showed that there is a lot of difference of opinion about which shift levers take up how much cable. So, I did some measurements on the 13 units that were lying in the box.

In the table below, please realize that the "effective diameter" is appproximate: some of these don't wrap around far enough for an accurate measurement, and some don't have their wrap barrels quite symmetrical wrt the axle bolt or nut. Like the Campy BarCon wants to pull more cable per unit of angular change near high gear than near low.

effective diameter of some shift levers

Diameter

Brand

Position

Model or notes

20

Campagnolo

BarCon

biggest at high gear end.

24

Shimano

BarCon

Spring-loaded

23

Suntour

BarCon

Ratchet

16.4

Campagnolo

DT

raised letters

33

Cyclo GB

DT

for plunger derailleur

18

Shimano

DT

DuraAce

20

Shimano

DT

L422 ratchet

21

Shimano

DT

600

15

Simplex

DT

Al, black plastic covers

15

Simplex

DT

Plastic, chrome trim

18

Suntour

DT

ratchet

20

Suntour

DT

Cyclone (2 versions)

19

Suntour

DT

"aero" w curved levers

If your output is garbled, send me an email with this subject and I'll send it as a little xcel file, unless you ask for Word.

Converting from effective diameter to (mm. cable pull)/(degree lever moves) is left as an exercise for the reader. If it gets really dull this winter, I'll set up a jig and measure derailleur (mm moved)/(mm. cable pull), unless someone can find Berto's data. Hint, hint.

What does the effective diameter "data" tell us?

First, Campy ~ Simplex in effective diameter, if nothing else.

Second, the Japanese DT are roughly 25 - 30% bigger than the two European models. Move more cable. True for both DT and BarCon, within brands.

Third, here I thought Suntour was really smart, and used the same ratchet assembly both places. Not true. Really smart in selling lots of both is just as good, though.

I hope this is useful. For example, if you are having trouble hitting your shifts with that Ultra-7 with a Suntour BarCon, drop down a notch in quality and use the Campy -- it works fine on one of my bikes. Conversely, for faster shifts choose a bigger effective diameter.

Or confuse your friends. Put a Simplex DT on the bike with a Crane RD, and brag about the 170 degree shift sector ( guess) . :-(.

Your mileage may vary. If DC locals want me to measure others with my knife-edged Swiss plastic vernier with dial, just bring 'em by. Bigger databases are better.

harvey sachs
mcLean va