I've always thought that toe in adjustment would only last until the pad ha d worn to parallel with the rim surface e.g. not very long. Am I missing something? Kurt Sperry Bellingham WA
On 7/7/05, r cielec <teaat4p@yahoo.com> wrote:
>
> Ahoy !
>
> RE: Toe-in of Universals
>
> If caliper cannot be bent without high risk of breakage, is toe-in
> accomplished by reshaping the pad by cutting or filing or making tapered
> shims between caliper and pad holder ?
>
> Richard Cielec
> Chicago, Illinois
>
> HM & SS Sachs <sachs@erols.com> wrote:
> It happens that a few years ago I actually measured the lever movement an
d
> cable pull for some levers. The results, as a ratio of lever throw per un
it
> of cable take-up, are below. What you will see is that the Universal has
a
> very low ratio. Roughly speaking, moving the lever 2 mm shortens the cabl
e
> ~1 mm. In contrast, with the Weinmann "red-dot" of the early 60s (a perso
nal
> favorite), it takes 3 mm of lever travel to pull a mm of cable. As Joe B-
Z
> says, the Universal has uncommonly low mechanical advantage. Lots of cabl
e
> pull, very little force transmitted. It is not "powerful," but it is very
> direct since it takes up slack amazingly quickly and then has full contac
t.
> Then it is up to brute strength to get it to convince the pad and rim to
get
> intimately acquainted.
>
> Ratio, lever
> 3.2 DiaCompe
> 3.9 Weinmann Delta
> 3.0 Weinmann Red-Dot
> 2.1 Universal 61/68
> 4.2 Sachs "Ergo"
> 2.4 Shimano 105 Road (not sure which one)
>
>
> AT the other end, the caliper, you can do the same sort of measuring.
> Let's ignore the straddle cable geometry for now, and just think about th
e
> relative lengths of the lever arms (pivot is the fulcrum). It's roughly 2
:1
> for the CP-61 and 1:1 for the SP-68. So, a mm of cable pull moves the bra
ke
> pad roughly 1/2 mm with the 61 and 1 mm with the 68. That is one heck of
a
> big difference. So, all other things being equal, the 68 SP calipers are
> easier to modulate and require less pressure than the 61 CPs.
>
> My Hetchins came with Universal 61s. Even with the original pads, they
> inspire confidence by their combination of good feel/modulation and adequ
ate
> power with the force my 60 year old fingers can maintain. Last week, I se
t
> up 68s on my NOS Weigle, which wants longer sidepulls than the modern
> fashion, with Universal levers. It was a bit scary, and I will change to
> levers that need more lever travel to take up cable, so they have more
> mechanical advantage.
>
> Like most of us, Universals are quirky. In this case, great when set up
> right, impossible to adjust toe-in (guaranteed to break), lousy hood rubb
er
> but fine pads, poor chroming on the CP hardware... My own quirks are
> somewhat different.
>
> harvey sachs
> mcLean va
> Met a smiling chap on my morning commute today, at Key Bridge, NoVA. He
> gets to ride his only bike, a '72 chromed paramount, to work. My commutin
g
> bike would have a half-life (before theft) measured in hours parked outsi
de
> where I work...
>
>
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