Re: [CR]Sturmey Archer

(Example: Framebuilders:Masi)

Date: Wed, 3 Aug 2005 19:37:51 -0600
From: "Mitch Harris" <mitch.harris@gmail.com>
To: Mark Stonich <mark@bikesmithdesign.com>
Subject: Re: [CR]Sturmey Archer
In-Reply-To: <6.2.3.4.0.20050803144437.035e5888@pop.earthlink.net>
References: <380-2200583319264621@M2W038.mail2web.com>
cc: classicrendezvous@bikelist.org

So Mark and Greg, what is the lowest gear you use with a SA 5 speed? You mentioned a 50"-100" spread with a 42, and that sounds like your cog was a 15t with your middle gear (1-to-1 ratio) about 75". If you used a 42x18 for a 63" 1-to-1 ratio, would you get a low gear in the range of 40"? (Not sure how to figure the -33% +50% calculations.)

When mountain biking was getting popular in britain in the 80s riders were keen to set up mtb range hub gears and the CTC and other cycling resources would warn about blowing out your SA hub gears with too much torque on the low end.

Mitch

On 8/3/05, Mark Stonich <mark@bikesmithdesign.com> wrote:
> At 8/3/2005 03:26 PM -0400, kohl57@starpower.net wrote:
> >Definately. Although I must say the most reliable "sexy" SA hub gear is
> >the
> >AM (three-speed medium ratio). The four speeds (FM, FC) are swell and th e
> >FC sublime but I must say that lowest gear is often a ***** to get shift ed
> >down to. And stay in place. One of the many things a dad would tell his son
> >was "never stand in the saddle with a SA hub"... worth heeding with the
> >lowest gear on an FC. Someone told me they fixed all this around 1958 bu t
> >no one was buying such things by then.
>
> This is because the detents in the shifter can be overpowered by the
> high spring tension needed to get a 4 speed to shift into low with
> only one cable. I've never had an FM or FC apart, but the FW has a
> delicate 2 piece indicator rod that has to apply a lot of force. The
> 5 speeds are much simpler and more reliable.
>
> >I am not too sure about five-speed hubs... they were all wide-ratio and
> >kinda boring if you're looking for something "club bike" and sporty.
>
> The ratios are the same as an FW with another gear on top. Gaps are
> not nearly as wide as an AW. Given the numbers of young folks riding
> "sporty" single speeds these days, having to be a bit more flexible
> with one's cadence doesn't seem like a big deal. And, worth the
> extra range. Especially as my old legs haven't aged as well as it
> sounds yours must have. (If you're out kicking butt on your RRA, as
> Lance says "It's Not About the Bike".)
>
> >They also needed dual shifters, the kind that look they belong on a
> >Stingray or
> >a Chopper. You'd lose all respect from the club lads showing up with tha t.
>
> My friends and I have about twenty S5 and S5/2 equipped bikes, and
> none of us use those shifters. All that is needed is a simple 3
> speed trigger for the right side, and either a friction or trigger
> shifter for the rarely used left.
>
> For anyone thinking about going to an old SA hub:
> The dual cable 5 speeds and the FW 4 speeds shared almost all of
> the internal parts. And, most of the parts that wear are also common
> to the ubiquitous AW 3 speed. There are two sets of planetary
> gears. On the 5 speed you have essentially two 3 speed hubs. The
> left lever determines whether the ultra wide ratio (-33%, 1:1 and
> +50%) or the medium wide ratio (-21%, 1:1 and +26%) gearset is in
> use. Almost all riding is done in the medium wide set, and the left
> lever is only used to make high gear even higher or low gear even
> lower. Sounds confusing, but my decidedly non-mechanical wife got
> comfortable with it after one ride.
>
> To make all this work with a single cable 4 speed, one first shifts
> into "low", then pulls even further to engage the other gearset to
> get "Lower Low". Unfortunately, this requires compressing two
> additional springs, leading to the problems PC alluded to.
>
> I've converted 4 speeds to 5 speeds to get better shifting, not
> because I needed a higher gear.
>
> BTW, Post CR timeline, Sturmey came out with completely redesigned
> single cable 5 speeds, all with the same ratios as the S5s. The
> early ones were pretty bad, but the newer ones are supposed to be
> quite reliable. Too bad the market wouldn't support a "5M" or a
> "5C". It would be hard to spread development and tooling cost among
> the few dozen of us, worldwide, who might be interested.
>
>
> Mark Stonich;
> Minneapolis Minnesota
> http://mnhpva.org
> http://bikesmithdesign.com