12-25 cassette vs 13-26 cassette?

[Johnny5]

I currently have an 8 speed 12-25 cassette on my bike with a double 53/39 on the front. I've recently been cycling a lot of big hills as I want to improve on my climbing. Will a new 13-26 cassette help just that tad bit or is it not worth it? I quite like sprinting on the flats too so will loosing the 12 for a 13 cog at the back jeperdise this too?

Thanks.

 

[marinyork]

Right some approximate figures
39.4 inches to 107.1 inches on the 13-26 (V)
41 to 116 gear inches on the 12-25 (W).
A 28 goes down as 36.6

 

[Crankarm]

http://sheldonbrown.com/gears/

Put your front chain ring and rear sprocket sizes in the above calculator and compare to your heart's content.

I have 8 spd Campag rear hub with sprockets 12-21 on my hybrid and recently purchased a new 13-26 set of 8 spd sprockets as I couldn't find individual 23T and 25T sprockets. I intend slipping on the 26 sprocket when I do touring in the Alps or Devil's staircase in Wales should I feel the need. But 12-21 is currently fine for me in flatish terrain. I have a triple chainset 53-42-30 up front as sometimes the load I carry can be heavy but very seldom use the 30T chain ring unless I drop down to it by mistake.

However on my road bike I ride with a Shimano Ultegra 53/39 double chain set with a 9 spd Ultegra 12-25 rear cassette. These is no hill I have not been able to get up .


So TBH I would have thought there would only be marginal gains going from 12-25 to 13-26 rear sprockets in climbing terms but you may also have different intervals between other sprockets and you will spin out at a slightly lower top speed having the 13 as your lowest ring. The Sheldon Brown calculator can also show your speeds in each combination of ring and sprocket.

 

[Tynan]

I recently changed the rear from a 11-25 to a 12-26 (I think) with a 52 front and the 12 I get into one one downhill doing up to 34 mph so I suspect that 13 is going to cover you

 

[Renard]

I went from 12-23 to 13-26 (8spd) on my winter bike and its made a difference. My good bike is 12-25 (10spd). I'm not sure I notice any difference between the two on climbs although the advantage that the 26 bottom gear provides may be cancelled out by it being on a heavier bike. Overall I don't think that it will make a difference. I'm planning on doing the Bealach na ba challenge later on this year so will probably fit a 27 cassette for that though.

 

[marinyork]

So much of it depends on what hills and fitness. If you are there or there about struggling in the bottom gear and doing big Peaks climbs it could make a fair bit of difference. OTOH I got the impression Johnny5 was a bit newcomer to all the serious stuff with a serious and properly structed training schedule so will probably improve a great deal anyway. So maybe in that context it is unnecessary.

 

[Johnny5]

Thanks for the feedback.

As Marinyork has noticed, I am a beginner and have plenty or room to improve, and if the 13-26 cassette isn't going to help too much then I'll just keep training and make my legs stronger instead...probably the cheaper and the better option.