Re: [CR]Did the old racers use half-step gears?


Example: Production Builders:Frejus

Date: Mon, 03 May 2004 21:43:15 -0400
From: Joe Bender-Zanoni <joebz@optonline.net>
Subject: Re: [CR]Did the old racers use half-step gears?
To: Jan Heine <heine93@earthlink.net>, classicrendezvous@bikelist.org
References: <a05210611bcbc8a4d66c4@[66.167.140.138]>


Jan,

Why is it a "myth"?

These two examples seem like very custom setups for some special purpose. Is there evidence that examples like these were widespread?

The box stock arrangement would be something like 49-52 chainwheels with a 14-16-18-21-24 freewheel which is a classic half-step. My '59 Frejus came that way. Because the crossover gears really don't figure, any freewheel with 2 tooth or 3 tooth gaps in the middle 3 cogs yields a reasonable half step.

It's hard to avoid a half step given small chainwheel differences unless you go to the erratic freewheel progressions provided in the Koblet examples.

Joe Bender-Zanoni
Great Notch, NJ


----- Original Message -----
From: "Jan Heine"
To:
Sent: Monday, May 03, 2004 8:04 PM
Subject: [CR]Did the old racers use half-step gears?



> An often-repeated myth is that racing bikes before 1950 used
> half-step gearing. This is because the front chainrings often were
> relatively close in size, as they are on a half-step set-up.
>
> However, both Koblet's bike in the 1951 Tour de France (see VBQ vol.
> 2, No. 2), as well as the 1960 Olmo in the upcoming issue, show that
> the gearing was far from half-step:
>
> Koblet used gears like 48x52 with a 14, 16, 17, 18, 19 freewheel or a
> 48x50 with 14, 16, 18, 22, 24 or similar stuff.
>
> Charting the first gear ratios show a lot of duplication:
>
> 48 52
> 14 93 100
> 16 81 88
> 17 76 83
> 18 72 78
> 19 68 74
>
> The Olmo, according to the original sales sheet, used a 48x51 with a
> 13-26 freewheel. Assuming this was a 5-speed freewheel, the Olmo
> charts to:
>
> 49 51
> 13 100 106
> 16 81 86
> 19 68 72
> 22 59 63
> 26 50 53
>
> Toward the middle of the range, it is almost half-step, but the
> chainrings really are too close in size. You get five pairs of gears
> with big jumps in between. (Half-step means that all gears are evenly
> spaced).
>
> Charting Koblet's gears shows it is even further from half-step, yet
> they obviously spent lots of time thinking about their gears: Most
> racers then used different sizes of chainrings almost for every
> stage, much to the chagrin of the mechanics (which were provided by
> the organizers back then).
>
> Also, the recently posted report from Jobst Brandt showed no evidence
> of half-step gearing, as far as I could tell. (The fact that he
> changed the freewheel ratios without changing chainrings indicates
> that it cannot have been half-step, as the two are interrelated with
> half-step: Chainring size difference must be half (in %) of freewheel
> cog size differences.)
>
> So if it wasn't half-step, what was the reasoning behind those gears?
> Anybody know? Maybe Jobst would know. Does anybody have a contact for
> him?
>
> --
> Jan Heine, Seattle
> Editor/Publisher
> Vintage Bicycle Quarterly
> http://www.mindspring.com/~heine/bikesite/bikesite/