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I am currently building a road bike. I measured the chain using the largest ring and largest cog method, I counted two extra links and cut the chain using a chain tool.

Both ends of the chain now have narrow ends. I want to use a power link, I understand that if I use the power link to join the ends, the chain will be one link longer than necessary.

How can I remedy the situation?

Appreciate any help.

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You put the powerlink on the chain and move on with your life. Provided the chain is not insanely too long, it's going to work fine unless you're on the boundary of what your shift system can handle in capacity (which almost nobody is) and you're abusive at this boundary.

Note that the article clearly states how to size when accounting with a master link:

MASTER LINK NOTE: If the bike chain uses a master link, it is necessary to account for the link. Install one half of the master link on one side of the chain. Size the chain by cutting the other end of the chain.

If your chain is too short, you can jam your RD in large-large. If your chain is too long (as in this case), it may droop a little bit in smaller cog+chainring combos, but with 1 or 2 links too long, it will likely be insignificant (and occur in combos you don't use anyway).

  • Very much agree with this. I recently put a new chain on my bike, and even though I have a small cassette (23 tooth), I just ended up putting the chain on and attaching the power link. Last time I did it I took a few links off the chain to account for the fact that my large-large combination isn't that big, but I figured that taking the time to shorten the chain is more trouble than it is worth. – Kibbee Mar 29 '16 at 20:16
  • Well, I think that might leave a few too many links depending on your drivetrain and what chain you buy. I think most people will need to shorten it a bit. But I normally just size the chain using the old one -- its quicker for me. – Batman Mar 29 '16 at 20:29
  • Everything seems to be shifting fine enough. I don't recall if I tried putting it in small-small to see how much slack there is, but I have a triple so I only really go into the small ring when I'm climbing significant hills, in which case I'm going to be in the top half of the cassette. – Kibbee Mar 29 '16 at 20:34
  • If you do as @Batman suggests and size the chain using the old one (which I usually do), don't forget to account for chain wear/strech. Your new chain most likely should be one or two links shorter than the old one. – anderas Mar 30 '16 at 15:23
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The chain will be one link longer than necessary. How can I remedy the situation?

You don't. That situation is remedied by the device known as the "tension wheel": the bottom one of the two small cogs in the derailleur. Under spring action emanating from the joints between the derailleur parts (hanger-pivot and pivot-cage) the tension wheel picks up slack in the chain.

The tension wheel is necessary because various gear combinations generate various amounts of chain slack (relative to the most tense combination of largest ring to largest cog).

Given that your chain fits into the tightest combination (largest ring to largest cog), try shifting to the extreme opposite: smallest ring to smallest cog. You will see that the derailleur picks up this extreme amount of slack by the tension wheel swinging radically rearward. If the chain is not too loose in this situation, and isn't rubbing against itself anywhere (or coming close to doing so), then everything is cool.

The derailleur can pick up slack in excess of the minimum; a few extra links won't exceed its range. It's a good idea to have a few extra links in the chain, in case you have a road-side repair emergency that requires you to splice out and throw away a damaged link.

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Check the chain in place, on the small chainring and the smallest rear cog. As long as your B screw is pretty much set then you should have around a 1cm (3/8 inch) gap between the chain and top jockey wheel of the rear mech when in this position.

If the chain is rubbing against the jockey wheel, then its too long and if theres a larger gap it is too short.

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    Without knowing what the OP has at the front (chain rings), this isn't going to work. – Chris H Mar 29 '16 at 21:16
  • "not work" in the sense of jamming the chain when you go large-large, and possibly breaking the rear derailleur. So it's bad advice, but also dangerous advice. – Móż Mar 29 '16 at 21:34
  • The B screw is a gimmick; it makes no difference. I've fiddled a B screw on several derailleurs (such as a Shimano Acera) from one extreme setting to another. It didn't make any noticable difference about where the jockey wheel sits (how far from the chain) in any gear. – Kaz Mar 29 '16 at 22:28

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