Is my chain too long?

[Chicane-UK]

Earlier this year I did my first ever bike build with a Planet X Carbon Nanolight High Modulus frame and a full Shimano 105 5700 groupset. It all came together perfectly and I've been enjoying putting some miles on it.

However one thing which is really starting to irk me.. I think I might not have shortened the chain enough when assembling the bike. When riding on the smaller chainring and on a small cog on the cassette I'm finding when I ride over uneven roads the chain is regularly (and loudly) smashing on the chainstay. I also notice that the rear derailleur cage plate (the bit with the two jockey wheels) is almost horizontal. It makes me think I've not took enough segments out the chain and it's just too long.

Does this seem about right? Or the chain clouting on the chain stay normal? I'm just a bit worried about damaging the carbon!

[itsnotarace]

Put the chain onto the largest front chainring, smallest rear sprocket (11 ot 12t). The chain is the right length when the rear derailleur is at right angles to the ground (assuming you draw a vertical line through the two jockey wheels)

[walm]

Why would you be small up front and small at the back?
Use the front mech you lazy bugger!

Or what itsnotarace said...

[Chicane-UK]

itsnotarace said:

Put the chain onto the largest front chainring, smallest rear sprocket (11 ot 12t). The chain is the right length when the rear derailleur is at right angles to the ground (assuming you draw a vertical line through the two jockey wheels)

Did that when I fitted it, following the information in Zinn and in the instructions that came with the chain.. but I'll double check again later when I ride home

[itsnotarace]

In that case, yeah as above - don't use the small / small combination. Cross chaining is not a great idea as it unduly wears everything anyway