"B" screw (speed tension) adjustment question

[michael whiteman]

Is it possible to adjust this on a Shimano derailleur without the shift cable attached?
My gut feeling is NO, but I would like confirmation. Thank you.

 

[LewieBike]

It would be good to see an image of what you're doing.

Generally the "B" screw is used to set upper jockey pulley distance to the biggest cog while you try to not over stretch the derailleur's capacity for the cog set. You should always do this with the gear cable/housing attached as they combine and add or subtract to the upper pivot's springing rate. Which is part of the reason why Shimano put the "B" screw on their derailleurs.

Also, trying to stuff in a bigger low cog-gear than your derailleur can handle will make any of the futzing about moot.

 

[Sidewinder Jerry]

Most rear derailleurs you can look up the specs on them and they'll tell you the largest cog it can handle. On the majority of department store bikes those rear derailleurs a 34t cog is the max you can go with them. I custom built a 7 speed 34-13 freewheel to use with my SI triple chainring shift kit (34,28,24,21,18,15,13).

 

[LewieBike]

Most rear derailleurs you can look up the specs on them and they'll tell you the largest cog it can handle. On the majority of department store bikes those rear derailleurs a 34t cog is the max you can go with them. I custom built a 7 speed 34-13 freewheel to use with my SI triple chainring shift kit (34,28,24,21,18,15,13).

Yeah that must of been an early STI cog set before they started riveting together the cassettes. The LX level of Shimano 21 speed triples that came out in '89 were a nice gearing system.

 

[michael whiteman]

Thank you for the confirmation. I presumed I would need to have the shift cable attached because this determines the limit of one direction the derailleur moves. The "B" screw sets the other. I have nothing worth looking at right now. Just a bare stripped down frame with the rear wheel in place.

 

[Sidewinder Jerry]

Yeah that must of been an early STI cog set before they started riveting together the cassettes. The LX level of Shimano 21 speed triples that came out in '89 were a nice gearing system.

True many of the cassette cogs of today are riveted together. However most of the freewheel cogs still use spacers between them.