rdtompki

We had switched my wife's CF road bike (Shimano 105) to a straight bar 11-36 9 speed. It's a triple with 30-36 and I like to keep this low gear. Problem is she wants to go back to drop bars and the cheapest way to do this is to buy a new chain and 11-36 10 speed cassette. Seems like the Shimano CS-HG81 is the least expensive way to go and while possible heavier should work just fine with the original 10 spd. 105 brifters. Am I missing something?

mechBgon

The one gotcha I'd watch out for is the 10-speed chain on a 9-speed crankset. What you don't want, is for the narrow chain to "skate" on top of the teeth of the chainring you tried to shift down to, rather than engaging the teeth properly. Other than that, you should be ok as long as you don't put a DynaSys 10sp mountain rear derailleur on there (different actuation ratio on those).

JiveTurkey

I'm guessing you kept the original 10-speed crank?

Everything checks out to me:
- Original 10-speed shifters, crank, front derailleur
- 9-speed MTB rear derailleur (already got to use for the flat-bar setup?)
- new 10-speed cassette and chain

rdtompki

The crank is the original 10 spd triple and we replaced the 105 RD with a 9 spd. MTB RD which works fine on the 9 spd 11-36 so I'm good I believe. I have the same RD on our tandem working just fine on a 10 spd 11-32 (using a Jtek with Campy however. Love those Campy shifters)

Sangetsu

For what it's worth, I have used a 10 speed chain on 8/9 speed crank set with no problems.

digger531

You could find a 9spd brifter on craigslist or ebay. Might actually be cheaper.

davidad

You could also replace the silly 30t small ring with a 24.