Chain length with bigger cassette

Ak47mh

Hi

I am off to Majorca next w/e doing three long days in the saddle up the popular climbs.

I currently have a standard 53/39 with an 11/25 on the back on the summer bike. Whilst not a bad climber, I am considering sticking an 11/28 on the back just to give me that extra breather.

Do I need to add anymore chainlinks to the existing chain length (will buy a new chain and cassette)? The bike has Di2 which I presume won't need any adjustment either.

Cheers,
Ant

gethinceri

Stick an 11/28 on Ant, you'll never keep up with the boys otherwise.
You're right, you're not a bad climber.

drlodge

Whether you need an extra link or two depends on how your chain length is set at the moment. Try it on small-small and big-big and look how much slack the rear derailleur is taking up. You'll need the chain as long as possible so that in small-small there is still some tension in the chain and in big-big the rear derailleur cage still has some movement forwards possible to cater for the bigger sprocket.

Ak47mh

Lol cheers Geth, three days with Mr Rogers and I am even considering sticking an electric motor on the back.

Thanks Drlodge as well, that makes perfect sense. I also found this and think I might need one extra link:

http://www.machinehead-software.co.uk/b ... hcalc.html

Bobbinogs

That machinehead site works pretty well but will really just confirm what you can see from looking at the RD. Don't be tempted to reuse Shimano pins for an extra link as they are designed with a mushroom top which deforms when the pin is removed. Sudden chain failure can be a holiday ending event.

You may find a 12-28 is more than enough with a standard double, even when descending big mountains. It can often be quicker and safer to get into a decent tuck and then concentrate on lines and the road ahead. It will also keep your current range which can help on long climbs as you will avoid abrupt jumps between the cogs.

Ak47mh

Thanks Bobbinogs, good advice.