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chain ring/cassette selection
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I am going from flat to very hilly on a vacation ride. I currently run a 52/36 chain ring combination and a 12/24 Cassette. Any recommendations on which end to change in what combination?
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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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How hilly and how strong are you. For example, I put a 11-28 cassette on my bike with my 52-36 chainrings for a 60 mile ride with about 8K of climbing. Most of the mountains were under 8% with just a few sections probably around 10%. I was mostly on my 25 tooth with a few rests on the 28. I did some rides a year ago that included some 20% climbs, and they were miserable on the 28 tooth, but doable.

If your power to weight is north of 3 watts/kg, then a 28 tooth is probably fine for the most challenging rides. But, if you are bellow 3, then you might want to consider stepping up to a 32 in back, which would also likely require a different RD.

You are really not getting much of a % difference by going to a smaller chainring set, so I would not bother with that.
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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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Also depends on the your current rear derailleur. Most rear derailleurs will handle a 28, newer ones will handle a 32.

What do you have?
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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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3W/kg 20-min best here. I LOVE my 11-32 cassette. When grade >6% or I don't feel like doing threshold power at 70 rpm, I'm so grateful to have that 32-tooth cog.

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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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Since you underlined hilly then I'll say get an 11-30t if you run Dura Ace (easiest available), 11-32 if you run Ultegra or 11sp SRAM, or 10-33 if you have SRAM AXS. SRAM AXS has a 10-36, but that'd take a pretty nutty hill to need 1:1 gearing.

Dimond Bikes
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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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Argonaddict119 wrote:
I am going from flat to very hilly on a vacation ride. I currently run a 52/36 chain ring combination and a 12/24 Cassette. Any recommendations on which end to change in what combination?

I'm a 5w/kg FTP rider, and live in Switzerland. I ride a 52/36 and 11-30 cassette most of the time. I can climb big passes on a 25 cassette, however, its not fun standing and grinding for 1-2 hours

Pretty much every RD for the past 10 years will take a 30 tooth cassette, the exception being Dura Ace 10 speed which sometimes does and sometimes doesn't depeding on hanger position

Most people in local cycling club have a 32 or 34 cassette and compact chainset.... but I don't really think that is necessary
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Re: chain ring/cassette selection [exxxviii] [ In reply to ]
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exxxviii wrote:
How hilly and how strong are you. For example, I put a 11-28 cassette on my bike with my 52-36 chainrings for a 60 mile ride with about 8K of climbing. Most of the mountains were under 8% with just a few sections probably around 10%. I was mostly on my 25 tooth with a few rests on the 28. I did some rides a year ago that included some 20% climbs, and they were miserable on the 28 tooth, but doable.

If your power to weight is north of 3 watts/kg, then a 28 tooth is probably fine for the most challenging rides. But, if you are bellow 3, then you might want to consider stepping up to a 32 in back, which would also likely require a different RD.

You are really not getting much of a % difference by going to a smaller chainring set, so I would not bother with that.

depending on the age of his setup (i'm guessing it's older since he has a 12t small cog, which is common on 8 and 9s systems, less common on 10 and 11s) it may be difficult to find a RD.

a derailleur hanger extender will let him fit a larger cassette in the back as well. that might be an easier solution than a new RD. might be a little finicky as the max spread capacity is exceeded (chain could be slack in the small-small combos).

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Re: chain ring/cassette selection [JasoninHalifax] [ In reply to ]
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I am 63 years old and have a 2 watt/Kg power to weight ratio. My rear derailleur is a new Dura Ace. I do have a 11 tooth cog which I will put on for down hill. Northern Arkansas so I guess I will go with a 30 tooth on cassette.
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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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I have never heard of a 12-24 cassette.

What brand and model is it?
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Re: chain ring/cassette selection [jimatbeyond] [ In reply to ]
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sorry `12-25
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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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The current Dura Ace will take a 30, I have fitted a 32 to a couple of bikes, but 32 does not work on other. I would also recommend getting a compact 34 tooth inner ring, Its not recommended by Shimano, but know several people who run a 34/52 front chainset with 11-30 cassette

Regarding 12 tooth cassette, my TT bike setup is a 42/55 chainset with an 12-25 cassette, this gives nicely spaced ratios and a great chainline when riding above 40kph (25mph) on the flat
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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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Argonaddict119 wrote:
I ... have a 2 watt/Kg power to weight ratio.
I would put an Ultegra 11-32 cassette on. Go big. If you are climbing anything over 5% for any amount of time, you will want every tooth you can find.
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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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You say "very hilly" but it's all relative to what you consider normal.
I'd typically consider any ride with an average of less than say 4m altitude gain per 1km of ride distance "flat". 5-10m/km would be "a bit hilly", 10-20m/km is pretty hilly, and I'd reserve very hilly for routes with >20m/km. I may have done more extreme hill repeat training sessions but the most "hilly" event route I've done was about 30m/km over a distance of 174km.

Anyway, I'd always err on the side of having easier gears than you expect to need and not using them, rather than needing them and not having them.
I can hold 3W/kg+ for long periods without difficulty, and I'm pretty happy grinding away in a big gear at 60rpm. Nevertheless, if I'll be riding lots of 10%+gradients I like to have 34/28 or 34/32 available. I changed the cassette on my road bike to an 11-32 a few years ago, as a precaution when doing to La Marmotte in the Alpes. I left the cassette on the bike until it needed replacement. Close spaced gears are nice but adequate range is nicer. The replacement is an 11-30 because I know from experience that 11-32 wasn't essential and the jump from 14T to 16T on the 11-32 cassette was a little irritating and the 11-30 pushes the first 2T jump up to 15T-17T, a slight improvement.

Will your routes have lots of shallow gradients or will you be riding up steep climbs in the 8%+ sort of range? Shallow hills don't necessarily need a huge gear range, but steep gradients will make "easier" gears highly desirable.
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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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11-30 cassette and a new chain.
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Re: chain ring/cassette selection [Ai_1] [ In reply to ]
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My first time so I am not sure what to expect in the Ozark Mountains in Northern Arkansas
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Re: chain ring/cassette selection [Argonaddict119] [ In reply to ]
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I live in a hilly area and I made due with my 53/42 front and 12/26 (9 speed) rear for a long time. Just recently, I figured it was time to change out the chain + cassette, and I bought an 11/32 for the rear.

With the initial install, I didn't adjust the rear derailer properly, and this lead to the demise of the brand new chain I had just installed.

My lessons learned:
- Properly determine the correct length for the chain. After destroying the first one, I followed the steps on SRAM's website on how to get the correct chain length for a road bike while I was installing the second chain.
- Adjust the "B" screw on the rear derailer to make sure there is enough of a gap between the rear guide pulley and the largest gear on the cassette.
- I really didn't need the 32. I could have just gone with an 11/28 and that would have been enough.
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Re: chain ring/cassette selection [trislayer] [ In reply to ]
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good advice thanks, and thanks to all who responded.
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