# Changing rear cassette ratio for easier hill climbing.



## Doug. (28 May 2011)

Hello.
I am going to change my rear cassette,as I am finding some of the very steep hills...incredibly difficult to climb.
My bike has a Shimano 105 group set, 10 speed (compact 2 chain rings)
Presently the rear cassette is 13 to26.
The following cassettes 11 to 28 or 12 to 27 are available, please may I have a suggestion of which cassette will be the most suitable for those long steep climbs ?
Thank you.
Doug.


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## Angelfishsolo (28 May 2011)

I would go 11 to 28. You will have greater speed from the 11 and better climbing power from the 28. You will possibly need to adjust the limit screws on the rear mech slightly.


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## RecordAceFromNew (28 May 2011)

Of the choice of two, I agree with Angelfishsolo's suggestion. 

However you might also want to think about whether the 2 extra teeth (from 26 to 28) is going to make enough of a difference for your hills and worth the money for the switch.

If you have the GS (i.e. not short cage SS) version of the 105 rear mech and if the upper jocket wheel is no less than 13mm away from the 26T at the lowest gear currently, you will be able to go for a 11-32 (or more, for every additional tooth you need another 2mm of clearance) at the additional expense of a longer chain. Just a thought.


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## Cardiac (28 May 2011)

Depending on the compact (50/34...?) you may find that the 11-28 cassette is just outside the range that the rear derailleur can cope with. If you have the SS (short) cage version it may need some very careful setup. The issue is a function of the maximum amount of slack that the system can accommodate (difference between small and large chain ring plus difference between small and large sprocket). According to the Shimano documents, the RD-5600 SS on my bike can accommodate a difference of a total of 29 teeth with a largest sprocket of 27T. The GS cage will allow a difference of 37 teeth. Other 105 models may vary slightly I imagine.

Having said that, I have read that is is possible to push the limits a little with careful setting up. I would try the 11-28 cassette and see how it goes. If it doesn't work well, resale prices for little / unused parts means you won't really lose out that much. 

I looked at doing this myself, but there aren't enough hills around here to justify the effort - I will be better of just getting fitter.


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## HLaB (28 May 2011)

If you are not finding your existing cassette too big a jump between gears, I'd go for the 11-28, improving your top speed but giving you a lower gear for climbing. I though however as said above a 27t was the limit before the derailleur needed changed, if not I'd definitely go for the 11-28 :-)


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## Sittingduck (28 May 2011)

I recently went from a 12-25 to an 11-28, as I could only see win-win 
The 11 gives a higher top end and I only use the 2 larger sprockets for big(ish) hills. Might aswell have a 31" gear instead of a 36"!
Managed to get up a fair size hill 2 weeks ago on the 34-28 combo, only stopping twice for brief respite  Last time I tacked the hill in question, I had to stop 4 times...


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## rockyraccoon (28 May 2011)

Hi sittingduck, did u have to change the rear derailleur? Also what groupset do u have?


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## Sittingduck (28 May 2011)

User14044raccoon said:


> Hi sittingduck, did u have to change the rear derailleur? Also what groupset do u have?




Shimano 105. No, didn't need to swap out the mech, it handles the 28 ok


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## Banjo (28 May 2011)

Sittingduck said:


> Shimano 105. No, didn't need to swap out the mech, it handles the 28 ok




I changed to 11 28 from 11 25 on my Shimano 105 Triple and it worked fine .


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## Will1985 (28 May 2011)

If you're finding it _incredibly hard_, I don't think one extra climbing gear is the solution. You're sacrificing some decent middle range ratios for 2 top end gears and 1 bottom end gear.
While it would be a more expensive option, a triple chainset might be a better solution to your problems. You could always keep the current chainset to put back on once you can climb hills better.


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## Sittingduck (28 May 2011)

I checked the middle sprockets before ordering mine and as far as I could tell, it was only missing a 16t (goes from 15 up to 17, on the 11-28).


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## Doug. (30 May 2011)

Hello.
Many thanks for the replies.
Doug.


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## DreamBig (28 Mar 2012)

Today I came across a nice app called Bike Gear Calculator, www.BikeGearCalculator.com I had the same dilemma to get compact or not. this gear calculator gave me the answers I needed. Switching to compact now. As it turned out there are so many things to take into consideration. http://itunes.apple.com/app/bike-gear-calculator/id505985340?ls=1&mt=8


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