help with cassette

No.

Quoted post said:

I do most of the riding on flat and down hill areas.

How is that possible? Take a taxi to the top of each hill? 😎

sp103154 said:

Will I get added force with the 11 tooth cog and will I need to replace the chain for this change?

Tx

If you use the same cadence (crank RPM) compared to the 12 tooth cog, the 11 will increase your speed by 9.1% (12/11=1.091)

Your chain might or might not need replacing depending on actual wear.

sp103154 said:

I bought a Shimano cassette 11-12-13-14-15-17-19-21-25 to replace a 12-13-14-16-18-19-21-24-27 as I do most of the riding on flat and down hill areas.

Will I get added force with the 11 tooth cog and will I need to replace the chain for this change?

As stated, unless changind the number of speeds, 9 to 10, chanis are replaced based on wear and stretch.

Force or effort should remain almost the same, read your heart rate, cadence also, the variables being the road, up, down, flat and the gear you ride in.

I started out with a 12-25 cassette and most of my riding was on the flat. I found the best benefit was from a cassette with two of the missing gears included, a 13-23. It has the 16 and 18 tooth sprockets, just right for into the sea breeze and a couple of rolling hills along the railway line. 😉

sp103154 said:

I bought a Shimano cassette 11-12-13-14-15-17-19-21-25 to replace a 12-13-14-16-18-19-21-24-27 as I do most of the riding on flat and down hill areas.

Will I get added force with the 11 tooth cog and will I need to replace the chain for this change?

Tx

Technically, there will be greater chain tension when you are riding on the 11T cog than when the chain is on the 12T, but the differences should be neglible in terms of what this means for chain wear.

John M said:

Technically, there will be greater chain tension when you are riding on the 11T cog than when the chain is on the 12T, but the differences should be neglible in terms of what this means for chain wear.

The funny thing about this is it is much less likely to break your chain. The force runs in one smooth curve without any big peaks. The most likely person to break a chain is a mtber going up a very steep hill in a granny gear. The acceleration is so great and the gear so low that the force runs in a series of very high peaks. compared to a high gear that is. That is why the greatest number of chain breaks comes from steep uphills in the lowest possible gear.

sp103154 said:

I bought a Shimano cassette 11-12-13-14-15-17-19-21-25 to replace a 12-13-14-16-18-19-21-24-27 as I do most of the riding on flat and down hill areas.

Will I get added force with the 11 tooth cog and will I need to replace the chain for this change?

Tx

Dude,

perhaps force is not what you really want. perhaps you want gear ratios. in that eventuality go to Sheldon Brown's gear ratio calculator, sheldonbrown.comgearsOpen ↗.

Where are you riding? I live in the Midwest where it is mostly flat and windy. Where is it mostly flat and down hill? Did MC Escher lay out the roads where you live?

I run a 9 Speed set up and find that it is more benificial to run a 12-13-14-15-16-17-18-19-21. I have a dura ace 53-39-30 triple crank. I find that minor tweaking in the middle range of the cassette is more benificial with varying wind conditions than having a very low or a very high gear. With a triple i don't need a very high gear cause i have the 30 tooth bail out on the crank.