I upgraded a customer's bike from Shimano 10-speed to 11-speed,
and among the rear derailleur, chain, and sprocket I replaced,
the chain was clearly stretched so I discarded it.
I cleaned the rear derailleur and sprocket before handing them back, but
the sprocket is worn down so much that reusing it might be impossible.
This is the first time I've seen chain pin marks embedded into the tooth tips to this extent.
Huh? You're asking why I could convert to 11-speed by replacing only three components—rear derailleur, chain, and sprocket?
Well, just hypothetically speaking,
if with Shimano electronic components the number of gears and the amount of movement per shift operation were determined by the derailleur rather than the lever, then you wouldn't need to replace the lever.
Only the ST-7970 has a different connector format from all subsequent components,
so the only 10-speed lever compatible with 11-speed components is the ST-6770.
Which means starting from a complete 6770 setup, if you swap in a 6870 rear derailleur,
convert the sprocket to 11-speed,
use an 11-speed chain, and adjust the front derailleur for your 10-speed crankset,
then the 11-speed conversion could be accomplished with just those three components—rear derailleur, sprocket, and chain.
When you connect a bike in this mixed configuration to a computer,
you'll get a message like "incompatible, don't do this,"
but as long as the bike's actual mechanical work is sound, you're fine.
The content of this article is not fine.
and among the rear derailleur, chain, and sprocket I replaced,
the chain was clearly stretched so I discarded it.
I cleaned the rear derailleur and sprocket before handing them back, but
the sprocket is worn down so much that reusing it might be impossible.
This is the first time I've seen chain pin marks embedded into the tooth tips to this extent.
Huh? You're asking why I could convert to 11-speed by replacing only three components—rear derailleur, chain, and sprocket?
Well, just hypothetically speaking,
if with Shimano electronic components the number of gears and the amount of movement per shift operation were determined by the derailleur rather than the lever, then you wouldn't need to replace the lever.
Only the ST-7970 has a different connector format from all subsequent components,
so the only 10-speed lever compatible with 11-speed components is the ST-6770.
Which means starting from a complete 6770 setup, if you swap in a 6870 rear derailleur,
convert the sprocket to 11-speed,
use an 11-speed chain, and adjust the front derailleur for your 10-speed crankset,
then the 11-speed conversion could be accomplished with just those three components—rear derailleur, sprocket, and chain.
When you connect a bike in this mixed configuration to a computer,
you'll get a message like "incompatible, don't do this,"
but as long as the bike's actual mechanical work is sound, you're fine.
The content of this article is not fine.