I'm considering making the above change in crank sets primarily because 53/39 is really hard on the hills here. I have 11-28 at the back.

I don't see a downside to this since it seems like I will always be in the middle of the cassette while climbing. Of course my speed on the flats will take a hit but I don't spend too much time on 53/11. Also if it seems like too much, I can always go for 11-25 in the back.

I'd appreciate any comments on your experience with a 46/30.

Update: So I decided to crunch some numbers. Also, I'm considering the IRD Defiant Wide Compact. The following comparison is between the usual compact (50/34) and the IRD (46/30).

Combinations with a chain angle greater than 1.5° are grayed out. I think this analysis confirms that my ability on flats and descents will be different (different gear ratios).

However, the effect on climbs (within the chain angle constraint) is equivalent to swapping the 2.43 ratio (on the 34) for the 1.25 (on the 30) which is fine by me.

enter image description here

First ride update: As expected, I can't mash and accelerate anymore, but it doesn't matter. I really enjoy the high cadence and the fact that I can still hit the same speeds as before (albeit slower). I'm looking forward to my first big climb on Wednesday!

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    Your front derailleur might not like the big chainring difference or the size of the chainrings. 16t for a double is a lot. Why not change your cassette (and possibly RD) for bigger range? – Batman Aug 9 '15 at 3:31
  • Go with compact like 48 34 – paparazzo Aug 9 '15 at 4:05
  • Are there any road bike cranks with less than 110mm bolt circle diameter? As far as I know 34 teeth is the smallest possible chain ring for compact cranks. You could change to 46/34 on the front and 12–30 on the back. – Michael Aug 9 '15 at 16:41
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    They aren't easy to find, but 94 bcd doubles are out there for the 30/46. IMHO, 30/46 makes a lot of sense for the non-racer in hilly terrain. Velo Orange makes one. – Fred the Magic Wonder Dog Aug 10 '15 at 23:50
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    I use 36/53 which is 17t and with a chain watcher it works pretty well. An older campy shifter setup with more clicks in the front definitely helps. – Fred the Magic Wonder Dog Aug 10 '15 at 23:53

The traditional 53/39 is basically what a pro would use, it's for speed as the top priority. Even some pros are using compact cranksets to help with climbing. 50/34 is the the normal next step down, but 46/30 just makes it easier again. Only drawback is that when shifting down to the small chain ring, the chain can come off. But a good derailleur should prevent this.

  • Thanks! I'll check with my LBS if the derailleur can take the shift. – Jacob Aug 9 '15 at 17:06

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