kosmo886

I've got 52/36 chainrings and currently have an 11-34 cassette. Considering going to an 11-30 for tighter range. How big of a difference will this be. Will a new chain length be required to make this switch?

diphthong

where do you ride, what's your health like and how are those knees?

if you live and ride in flatlands/small mountains, an 11-34 is overkill.
if you live near but don't ride serious mtns, an 11-34 is a godsend for when you actually do.
if you love to climb, the 11-34 can, with you in semi-decent hill/mtns shape make the difference
between it being a tough and keep going ride vs killmenow/eject/worstrideever/justendit.

Dean V

No change in chain length required.
Do you need/use the 34 low gear you have?
If not you may as well get a 11-30 or 11-28.

Racing Dan

Tighter at what speed and cadence? Depending on your usual speed the 11-30 may in fact have less tight gearing than the 11-34. - linking myself:

https://www.bikeforums.net/21618051-post101.html

Another point is, no one needs 52/11 on the flats unless they are Superman.

xroadcharlie

Use Sheldon Browns bike gear calculator to check the gearing on your current cassette and one your considering. Set it to show % jumps.

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

Generally speaking keeping them in the 10 - 15% increase range is good. The low gears can go to 20% since the speed change is so small.

If your current cassette meets that criteria, You don't need to do anything. That said, If you find one that works better in the gears you use most, It might be a an interesting excersize. Just make sure it goes to the lowest and highest gear you anticipate using in the near future. I like to have 1 gear higher and 1 lower just in case.