Thread: Component help
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Old 06-26-20, 05:10 AM
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Originally Posted by djb View Post
Its been a while, since tiagra went to 10 speed, but at that time, they changed the bcd of the crank, and 30 became the smallest granny you could put on.
I'm fairly positive of this, but check out out.
my fsa 10 yr old 50 39 30 can take a 26, but I'm fairly sure not a 24

For riding with a 39 or 40 mid ring loaded, I just find them too high.Have ridden both loaded and why I see a 36 as a better choice.
Sorry about the confusion. I am indeed using a 9-speed Tiagra, which is relatively new to me. I also have the same setup on an 8-speed Sora. Both are 130/74 BCD. However, the Shimano info on the Tiagra 10-speed triple says the inner BCD is still 74, but the outer is now 110. The big difference on the inner is the switch to 4-bolt instead of 5. It may be that appropriate 4-bolt chainrings smaller than 30 are not available?
In any case, 3x9 can be set up with a very wide range.
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