Fronesis, thanks a lot. I took my bike to local shop, they does not seems concerned, and say it's probably a small issue and I could increase the chain length slightly
I guess I can increase the chain length, just think what if we have a 11-42 real cassett, then the small cog is exactly the same while rear cog is much larger and requires a longer chain? does my logic make sense?
Originally Posted by
fronesis
My 2 cents:
1. Yours doesn’t seem all that far off. Yes, it’s probably a bit more than 15mm, but not a ton more. No reason to worry about it.
2. I do suspect that your chain is a bit shorter than it could be. While in the biggest cog, your RD is being pulled so far forward that it’s almost in front of the cog. And since the lowest point of the cog is directly underneath it, pulling the RD forward means pulling it away from the cog. Your RD looks like mine did when the bike arrived. With a new, and slightly longer chain, my RD is more directly underneath the cogs, even when in the biggest cog. So if the gap of greater than 15mm bugs you, you could always install a new chain with 1 or 2 more links in it, and I’m pretty sure you’d be able to dial in the 15mm gap.
I showed you the picture of my wife’s bike (size 53). On my bike (size 55) the RD is in the exact same position, but I have the b screw is threaded in even further.