Smaller chainring vs bigger cassette

11 speed Shimano slx
Currently 32 ring 46 cassette
Changing to a 30t ring gives virtually the same biggest climbing gear as changing to a 50t cassette

Any down side for climbing

Can your current rear mech cope with a 50t cassette sprocket?

I’d just change the chainring, save a bit of cash!

No idea what the bike is or what it’s used for.
But you’ll knock a bit off your top end speed obviously with the smaller chainring.

All about climbing 👍
Mech can cope no probs
Just thinking about being too spinny

I’m not impressed by the longevity of the super-large cassettes. Got less than 5 months from my Deore 51 tooth one.

4 teeth on the back is a big difference on climbs comparing mid gear range (say a 20T sprocket v a 24) but at low gears it’s far less of a relative change. Roughly half a gear inch in it for the two ratios you describe, so nothing in it really – you’d only notice on the steepest of climbs.

You could get a 50T cassette when your current one wears out, but if it’s just a gear preference issue get the 30T chainring.

It’s too give a better bail out option on a couple of local climbs that’s all

Lighter option also on bike and wallet lol

32 to 30 is only a 6% change so don’t loose any sleep over changing it.

As someone who is more interested in riding up as much as possible I’d recommend looking at a 28 oval.

For some peak climbs you’ll definitely appreciate it.

Do both. I managed to get another 28T in Germany this week and also a 10- 52T cassette.

Would prefer something lower but 26T doesn’t seem to exist any more 🙁

Not even considered a 28t never mind an oval 😭
That’s got me thinking

You get more anti-squat on a smaller chainring, which you might like – or not.

I found 34-10 on 27.5 was higher than needed almost all the time whilst 32-11 on 29 is usually high enough.

Interesting that people are opting for smaller rings than 30. I might investigate. Gearing opinions vary widely. In the gravel world people seem to think 36×42 is a low gear.

To the op I think 30 chainring if that’s a cheap swap. Change the cassette later if necessary

@thegeneralist I have a 26t oval on my cotic. Love it for the climbing.

Check out garbaruk. https://www.traversbikes.com/store.html#!/GXP-DUB-MTB-Oval-BOOST-chainring/p/250520501/category=64194014

Can highly recommend the cassettes as well.things of beauty worthy of being a musical instrument

I have a 26t oval on my cotic. Love it for the climbing.

Well I never….. 26T… awesome. Though I may have to tighten my limit screw again to further reduce my 12 speed Occam to 10 speed!
My 28T saws the chainstay in top gear if I let it.

Having just bought a new cassette and ring I’m not sure I can afford it

On the other hand, just imagine it…. 4 presses of the pedals for every wheel revolution – bliss. 26/52

Something else to consider is that smaller sprockets mean more chain tension. So 24 chainring to 36 cassette is the same ratio as 32 chainring to 48 cassette but the chain tension is 1/3 more.

Also thinking when not climbing it will move the chain down the block making the wear me even after swapping from a bigger Chainring #deeppockets #shortarms #yorkshireman

I’m not impressed by the longevity of the super-large cassettes. Got less than 5 months from my Deore 51 tooth one.

Can you elaborate on that – what mileage does that equate to, and in what manner did it prove lacking in longevity?

I had to get one of those early cassettes warrantied after 1750km because the rivets went on the spider holding the three largest cogs together, a known issue. I didn’t get any sense of premature wear other than that, and would like to think two years down the road Shimano have sorted that out.

Well I never….. 26T… awesome. Though I may have to tighten my limit screw again to further reduce my 12 speed Occam to 10 speed!
My 28T saws the chainstay in top gear if I let it.

I have a 24T on my Occam.

Of course I’m sensible and have a 34T too. Marketing, shmarketing!!

Something else to consider is that smaller sprockets mean more chain tension. So 24 chainring to 36 cassette is the same ratio as 32 chainring to 48 cassette but the chain tension is 1/3 more.

You’ve lost me. Can you elaborate?

🙂

Do you mean that the ring is tugging with only 12 teeth rather than 16, and so wears faster?

No he just means that the chain is tighter with more force in it. It’s like a lever. The small ring is nearer the pivot

Sorry, you’ve completely lost me.

C=2piR

Ie the radius of the lever is proportional to the circumference, not the square or the square root or anything fancy.
Same goes for the cassette. It’s the ratio of the two that matters. And the ratios in your example are the same

Yes, the smaller ring is near the pivot but so’s the smaller sprocket ( or whatever the ring on the cassette is called)

Bigger rings mean fewer articulations so lower drivetrain friction. Almost certainly more impact than the weight loss.

Yes, the smaller ring is near the pivot but so’s the smaller sprocket ( or whatever the ring on the cassette is called)

Yes, that’s why the gear ratio is the same. The point I’m making is as you scale down the diameter of both sprockets, you increase the tension in the chain, for the same pedal torque. As you reduce the lever length, you have to up the force to transfer the same torque.

Power =force x velocity

The slower the chain the greater the force

as you scale down the diameter of both sprockets, you increase the tension in the chain, for the same pedal torque. As you reduce the lever length, you have to up the force to transfer the same torque.

Exactly. So, you are more likely to break a chain. Plus, you have fewer teeth on your sprockets transferring greater force so you will probably wear out your sprockets faster if you are a masher because the loading on the engaged teeth is higher.

Im not really answering the OP’s question, but I’d just like to say that I love my 30T with my 11-51 cassette. I live on a hill with a very (very) steep climb straight from the house, and I’d really hate to go back to 32 or 11-46 now that I’ve experienced 30 x 51.

Edit: i haven’t noticed any deteroriation in life span compared to my older setups. But I’d still consider it worthwhile, even if I did.

I ride 29ers with 10-46t cassettes.

The lighter, short-travel bike works well with a 30t ring.

But for the heavy, longer-travel ones I need a 28t chainring.

No real detriment to climbing IME – though I don’t have any practical alternative without changing most of my drivetrain(s).

Note: 26 or 27.5 rear wheeled bikes will not need such small rings, so 28t on 29 is roughly the same effort as 30t on 27.5.