I'm changing the chain on my road bike and trying to size it correctly. The old chain was sagging while in the small rear sprockets and the small ring in front. (2x 10, 11-36t Shimano DT) I sized the chain using the big ring to largest cog method and added 2 rivets as was shown on the Park tools web site. When I do this however the lower 4 cogs in the rear allow the chain to sag considerably while on the small ring. If I set the gears to smallest to smallest then size the chain for that then the chain does not sag, or only slightly. When set like this though I can not reach the top 3 cogs in the rear when on the big ring in the front. Hmm.

I realize these extremities are probably not important and maybe not needed. So I'm wondering if I should leave it as is and not use the lower cogs while on the small ring to avoid the sagging chain; or set it for a tighter chain and not be able to access the larger cogs while in the big ring? (I don't like the sagging chain)

I know this sounds finicky but I want it to be set up well. Ride style; I live in Vermont and do a lot of decent climbs. I like to be able to have many options with gear combinations depending on the road. Thanks for any insights that the community can provide. Ride on.

Steve