New bike comes with semi compact 52/36 and 11-30 cassette (Dura Ace 9200) . My previous bike had a compact 50/34 and 11-30 cassette (Sram Red). My question is this: I ride in the French Alps about 6 weeks a year and hunt out long sustained climbs when home. Do I replace the cassette to an 11-34, which my calc would actually be easier in the 36/34 gearing than the previous 34/30 or do I replace the chain rings and back to a compact 50/34 and stick with the 11-30 cassette. Costs wise the chain rings seem marginally cheaper than cassette, but wondered what peoples thoughts were on if one way rather than the other is the better way to go from experience ? Any thoughts welcome.
For the Alps, I ride 52/36 with 11-34 and find the top and bottom ends spot on but your mileage may vary.
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âI never met a lower gear that I didnât likeâ - @ambermalika
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I had a 50/34 and an 11-34 on my S5. Great for going up steep slopes, but I seemed to spin out pretty regularly even on modest downhills.
My next bike will have 52/36 and an 11-34 to hopefully provide enough gear on both ends of my spectrum.
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Do you race on that bike? If not, Iâd change the chainrings. Since itâs usually easier to change a cassette later on, you then still have the option of changing to a bigger cassette too, if youâd like lower gears.
If you do race, you might want to keep the higher top speed of the 52-11.
Also some people are sensitive to the gaps in the gear ratios, which are more apparent with bigger cassettes, than with smaller chainrings.
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Iâd keep the chain rings and switch to 11-34 cassette. That gives you both a lower and a higher gear than your current setup which seems perfect for going up and down mountains!
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I ride a 52/34. I put it on for a cycling holiday in Tenerife. Its working though several years later so Iâve just left it. Changing the inside ring is cheap and easy too.
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Exact same dilemma as you that I was/am in.
I âaddedâ a second 11-34 cassette to the armory for those rides that will require some easier gearing, kept the semi as âeverydayâ riding.
The 11-34 goes on when I go to the mountains every 3-4 weeks for rides like 180km with +5200vm in two days.
I am content and enjoy tinkering with gearing so changing out a cassette and setting b-screw due to larger cog is not an issue for me. Also requires a second chain which is basically two rivets longer. All easy to do.
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Thanks for all the advice super helpful. Decision made. Swapped over the cassette to the 11-34 and as cartsman says, actually this gives me both a lower and higher gear option by keeping the 52/34. I also as SirDan says keep the 11-30 in the quiver should I need it again 
Thatâs not necessarily required for swapping between a 34 and 30 cassette. Your chain does need to be long enough for the 34, but itâs likely fine to use with the 30. I swap between two different wheelsets with those cassettes on my Aspero with 11-speed GRX and it still shifts great. I donât even touch the derailleur either.
Getting the disc brakes to not rub with either wheelset can be trickier, but also doable.
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This. Because, if youâre chain fits the 34t sprocket, itâll also fit all the smaller ones, like a 30t. The chain is too long if there is slack when in the smallest sprocket. But thatâs a 11t on both cassettes.
Itâs more likely youâd end up with too long a chain if you changed derailleur, eg from long cage to short cage, but thatâs a whole load more faff than changing cassette!
Why keep the 11-30? For flatter days?
I ask because I have a new 11-30 dura ace cassette that Iâm having trouble selling. I switched to 11-34 because all of my rides have climbing and I need the 34. Iâd gladly keep the 11-30 if I can find a good reason to use it.
Shimano also makes a 12-speed 11â36 cassette, which would give you an even easier bottom gear. IMHO you should always err on having easier gears when you plan on climbing.
Stick it on my winter bike, as will not be bothered to stick on eBay.
Personal preferences I would say, for myself at least.
We have races where its hilly, and where it fast and flat.
Using the 11-34 for the hilly races gives one the option of an out should it be needed. It usually is.
Using the 11-30 on the fast flat races, allows one to not skip the 16t (middle of cassette) and keep the gearing tighter.
Same as my gravel gearing, I have chainrings from 38-48t and cassettes that are 10-44, 9-46, 9-50 and 9-52. And I have used them all at various stages. I potter around as in âeverydayâ riding with a 46/10-44 XPLR, but race with the GX deraileur and eThirteen cassettes. Road pottering is usually with the 11-30 cassette. Road racing depends on course profile. My personal preference.
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Just to clarify, did you swap out the small chainring on the 52/36 with your old 34, giving you a 52/34 combo?