Re: [CR]Sturmey Archer explosions


Example: Bike Shops:R.E.W. Reynolds
Date: Wed, 03 Aug 2005 23:23:46 -0400
From: "Joe Bender-Zanoni" <joebz@optonline.net>
Subject: Re: [CR]Sturmey Archer explosions
In-reply-to: <8801bb2505080318374e3736c9@mail.gmail.com>
To: Mitch Harris <mitch.harris@gmail.com>
References: <380-2200583319264621@M2W038.mail2web.com> <6.2.3.4.0.20050803144437.035e5888@pop.earthlink.net>
cc: classicrendezvous@bikelist.org

SA went to a sintered sun gear at some point, maybe about 1972. This gear could be shattered at will by a torquey rider with anything over an 18T cog. We used to carry extra gears but changing out the sun gear took at least 30 minutes!

A few years ago a spun the swaged front chainwheel loose on the Ofmega crankset on a Specialized Globe (Italian model). They tried to sneak away from a warranty but I pointed out that this involved more than just proceeding forward as the bike used a coaster brake! Jeesh.

Joe Bender-Zanoni Great Notch, NJ

Mitch Harris wrote:
>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