Ok then. I now see you are right on this one. However if the left lever is set for the small chainwheel, I believe that the Symmetric feature should work as advertised. In other words the Symmetric suffers from dis-symbiosis in the big chainwheel only. My question now is why would Suntour not have been able to predict the big chainwheel conflict issue? I am not an engineer, and I can see it in my head without even setting it up.
Garth Libre in Miami Fl. USA
On Jul 5, 2007, at 6:00 PM, Sheldon Brown wrote:
> Quoth Garth Libre:
>
>> Sheldon Brown states in his web site that the 1983 Suntour Symmetric
>> levers had a serious flaw. He said that the movement of the rear
>> lever would cause the front lever to tighten, thereby pushing the
>> front cage closer to the big chainwheel and thereby eliminating chain
>> rub. He then stated that the flaw was that by constantly going up and
>> down in the rear, it would eventually cause the front derailleur to
>> progess too far and thereby causing a new problem. I finally obtained
>> one of these nice old shifters. I don't have a single bike that
>> doesn't have side braze ons for the levers, so I haven't verified
>> what he said ...BUT from my bench top view of things it does look
>> like the levers do not have this flaw. Instead of rotating the front
>> lever around, the internal cam pushes the lever forward in the
>> housing. As you move the rear lever back and forth it appears that
>> the other lever perfectly returns to the exact same position as
>> before. I think I have this right and it is just possible that
>> Sheldon is in error.
>>
>> Offered in humble questioning. Both Suntour and Sheldon are my
>> heros.... Garth Libre in Miami Fl USA
>
> That's 'cause you're operating it without a front derailer hooked up
> to it.
>
> If the left lever starts at the cable-fully-tight position and you
> then move it forward, the cable tension will twist the lever forward.
> When the assembly moves backward again, the front cable will no longer
> be tight.
>
> Sheldon "Never Seen These Work Properly" Brown
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