[Closed] Chainring ratios

first thing to check is that a 36 ring will fit on your chainset, a 53/39 combination might mean it's a non-compact spider so a smaller 36 bolt pattern won't fit

You need to buy a new chainset.

This might help:

https://www.mantel.com/blog/en/derailleur-capacity-maximum-techcenter

Thanks all
It's a Dura Ace 9000 if that makes any difference? I had it in my head that I can interchange the 52 and 36 chainrings with the 53 and 39's (simply from an "it will bolt on perspective") but I may be mistaken?

Would it not be cheaper and easier to change the cassette to give you the ratio's you need?

Shimanno have a compatibility chart to show what works with what.

https://productinfo.shimano.com/#/com

it says here that the Dura Ace 9000 uses a 110mm pitch circle diameter so you can fit a 36 ring on there

you'll need to check that your front mech can cope with it though

Replacing Dura Ace chainrings
Dear Lennard,
I have a Giant TCR SL 0 with Dura Ace 9000. The crankset it came with is 53-39. We are travelling to France soon with lots of climbing, so I want a compact crankset. I understand I can replace the front chain rings and leave the existing spider to change to a compact set. Do I have to change both front chainrings to 50/34? Or can I leave the 53 and change the 39 to a 30 giving me 53/30?
—Chris

Dear Chris,
Dura-Ace 9000 uses the same bolt circle diameter for compact and traditional double chainring pairs, so your one crankarm fits all chainring sizes. However, these are the only sizes Shimano offers in that four-arm design: 50-34T/52-36T/52-38T/53-39T/54-42T/55-42T

No, you cannot mount any smaller than a 34-tooth ring on one; forget the 30T ring. But yes, you could instead pair up 34-53 chainrings; shifting would be less than awesome, but pro teams sometimes use this combination for super steep stages, like the Monte Zoncolan in the Giro d’Italia.

You can just get the 34T, rather than the set. QBP (big wholesaler) sells individual Dura-Ace FC-9000 chainrings; it sells 34T, 36T, 38T, 39T, 42T, 50T, two different 52T — one for 36/52T, and one for 38/52T, 53T (for 39-53T, of course), 54T, and 55T.
―Lennard

https://www.velonews.com/gear/technical-faq-chainrings-and-living-the-zenzinn-philosphy/

Swapping just the cassette to an 11-34 will give you a fractionally easier gear than 36/30 (31.0 vs 32.4 gear inches). If like me, it will give you more climbing gears, at the slight expense of 2T sprocket jumps at the top end.

https://www.sheldonbrown.com/gear-calc.html

Might need a GS mech, plus ~2 extra chain links.

I ask as I wonder if 52/36 exists because 53/36 might be too different for the deraileur? No idea myself to be honest so just asking before I buy anything…

To get them to work at their best they make them in pairs, so you need the right versions too. It's probably more that the 53-36 don't have the shifting ramp's quite aligned.

You might still need to check the rear derailleur capacity, might need a medium cage if it doesnt already have one. My DA only just works with a smaller range.

Thanks for the responses all. T3ap0t, that article is perfect, thank you and the comment about the shifting ramps not quite aligning properly also very useful. Thanks all.