Crossing your chain

contadorbeef

I've been using 53/39 - 11/25 which is fine most of the time though I do sometimes run out of gears when out with the chaps in Wales doing The Steps, Horseshoe, Bwlch Penbarras etc whilst there all spinning with their compacts. So I've just bought a 11-28 which doesn't seem to run well on 53/25/28 now (chain bouncing off bottom jockey wheel), is this because I now need a longer chain or that you just cant cross the chain on those ratios?

andrewjoseph

shouldn't be doing extreme crossing anyway (small/small or big/big).

what exactly is the problem? I could understand if the top jockey wheel was bumping on the bigger cog on the back (adjust the B screw until it stops).

If the problem only occurs when cross chaining, stop doing it! Either stay in middle ring and use all the cassette or go into granny and only use the biggest 4-5 cogs.

this is what I tend to do on my road triple and on my mtb. granny and biggest 4 cogs for really steep stuff. middle and all the cassette for most riding. big ring and smallest 4-5 cogs for going fast.

reading back your post i assumed the '53/25/28' was a type for your triple setup. are you saying that when in 53 (big ring) you can't use the 25-28 cogs? if so, then it is not a good idea to cross chain.

cyclingfury

Strictly speaking you shouldn't really ride in a 53/25 or 53/28 gear as the chain is at too acute an angle. Having said that if your gears are nicely set up and running sweetly you can get away with it. (Pro riders seem to do this on a regular basis, but they don't have to worry about the premature wearing out of components!). I wouldn't personally do it though - by the time you've found the need to drop to the 25 cog whilst riding in the 53 ring you probably should have changed onto your middle/little ring, depending on whether you're riding a triple or a double.

John.T

is this because I now need a longer chain or that you just cant cross the chain on those ratios?

Both of these really. You should not use these 2 gears because the chain is too crossed and the same ratios are available on the small ring. See link to Sheldon Brown's gear calculator below. Also the bigger sprocket is causing the bottom jockey to be closer to the chain ring thus increasing the chain angle at the jockey.
http://sheldonbrown.com/gears/

contadorbeef

Thanks for the advice guys, yes I was talking about a double setup. It just seemed strange as previously the chain could cross from 53-25 with the 11-25 cassette on but as soon as I replaced it with the 11-28 cassette it struggled crossing after 53-22 any further to either 53-25 & 53-28. I'll replace the chain as it's probably struggling with the stretch (108 links at the moment) to (114 links) and then not cross the chain passed 53-22.

Headhuunter

It's probably because you have a short armed rear mech but if you're extending the range of the rear cassette and you want to cross the chain (which as above, is inadvisable) you need a longer armed rear mech...