Originally Posted by cascade168
Thank you all for your replies. I see now that I did not mention the shifters I am planning to use. I have some 8spd Ultegra barcons. So, if I understand correctly, I am good to go but I'll have one dead click.
In Shimano setups, the spacing is slightly different between 7- and 8-speed cassettes, but generally it's close enough to let you use 8-speed shifters with a 7-speed system.
There won't be any extra click if the derailer's limit screws are adjusted properly.
Originally Posted by cascade168
So, it was apparent to me that for some given amount of pull on the cable (in length) you get a corresponding side-to-side change (in width) on the derailleur parellelogram. Since both of these movements are distance measurements, they can be gauged and the actual ratio can be determined. As I now understand (thank you gmason!), this relationship is linear and is what you are calling "throw ratio".
Apparently different manufacturers use different throw ratios, but not always. And, some manufacturers may have different throw ratios within their own product line.
Ok, so last two questions:
Is there a straightforward way to make the measurements and determine throw ratio? (I am thinking that this is easier said than done).
It's not that easy to measure, but there is generally no need to measure it in practice, just match the brand of derailer to the brand of shifter, and the number of shifter clicks to the number of sprockets on the cluster.
Originally Posted by cascade168
Is there some reference where someone has already done the work and it's all recorded? or, do we all have to rely on our good friend Sheldon for the specifics?
See my latest article:
http://sheldonbrown.com/speeds
Sheldon "Numbers" Brown
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| As far as the laws of mathematics refer to reality, |
| they are not certain; and as far as they are certain, |
| they do not refer to reality. --Albert Einstein |
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