[python] Re: minq -- devious!

"Dirk Bonné" <dirk_bonne@xxxxxxxxxx> schrieb:

> General question, Are there guide lines for the minimum distance between
> BB and derailleur?
> 

Race-bike components are engineered for a chainstay-length between 390 mm and 
420 mm. If you want to use all gears of your cluster you shouldnt´t go to less 
than 360 mm, better 380 mm. I had 380 mm chainstays in my triathlon bike, 
friends of mine bikes with shorter chaistays - what was big stress for the 
chain when pedaling on inner or outer gears or the chain routing diagonal. Also 
bad shifting. But that´s only my personal experience. I´d prefer to use shifter 
hubs instead of chain shifting systems if there would be the need for a very 
short BB-to-axle-distance. 


> > "I googled for BEVO, they used an extra roller to handle the stress on the 
> > derailleur." 
> >  
> >
> 
> >This roller seems to be a MUST, if you use a derailleur.
> >  
> >
> May be I am just imagine things, but looking more at the minq2 pic, they
> might have a solution --without rollers!!!
> 
> If you have the rotation axis going very near to the end of the
> derailleur (the lower roller), you minimize the stress on the
> derailleur. In such a case the positon of the end of the derailleur
> doesn't change much when you turn!
> 
> It is a compromise of course, as you will always have a distance of the
> rotation axis to the tip of the derailleur, but may be they figured it
> acceptable.

You are right. For the stress on the derailleur this configuration will be a 
solution. But they have to pay the price of having a steering momentum caused 
by the chain-force. Chain is NOT pulling parallel to the steering axis. For a - 
in my personal opinion - better solution have a look on the following homepage: 
http://web.uct.ac.za/depts/psychology/bok/fwd.html 
Not so simple to build. 

And rollers again ;-)...     

B.t.w.: rollers on the not-pulling part of a chain produce nearly no power loss 
- but I´m shure, you knew it before ;-)


Cheers,
Christoph

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