[nemesis256]

I'm buying parts for my next bike and can't decide on a 30T or 28T chainring. Factors contributing to the struggle:

• I'm going from 175mm cranks to 165mm. Shorter = less torque = harder to push?
• Want to try an oval chainring instead of round. The downstroke part is the wider part right? So harder to push?
• Hoping to get an Advent X drive train instead of Eagle. My usual climbing gear is the 42 tooth, 50 for steeper hills. Advent X is smaller at 40 and 48.

According to gear-calculator.com a 48T cassette with 28T chainring is slower than 50T with 30T chainring. But that doesn't consider shorter cranks or oval. My goal is to keep the difficulty/speed as close to what I currently have. Thoughts?

 

[Mike Aswell]

If you really can't decide get a OneUp Switch.

FWIW you're not going to notice much difference due to the shorter crank or oval chainring, though oval can have a slightly unsteady cadence/feel.

The cassette change would be the most perceptible, though 50 to 48 is somewhat mild.

 

[308]

If you struggle with hills the 28 will do good for you. Going for a 175mm to a 165mm cranks length isn’t a huge deal and doesn’t make as much of a difference as the chainring size does. I run oval and love it.

 

[Shark]

As long as you aren't overly concerned about spinning out on long gravel or road descents, go for the 28.

Sent from my SM-G991U using Tapatalk

 

[006_007]

29er I would lean to a 28t, 27.5 the 30.

 

[ocnLogan]

The shorter crank arms should mean you need slightly different gearing, at least in theory.

If you do the math, it seems like the 28t might be the better choice. The 165mm cranks are 6% shorter than the 175mm’s, while the 28t is 5% shorter gearing than the 30t. So it seems that the 28t with 165mm cranks would be roughly the same as a 30t with 175mm cranks.

You might try cheap steel chainrings for a bit until you find the gearing you want.

 

[Jayem]

Whichever you get, your brain will program to you think it's normal and you'll get used to it in about 2 weeks.

 

[stripes]

29er I would lean to a 28t, 27.5 the 30.

Agreed. I run a 30t for 27.5, and a 28t right now for 27.5+.

 

[uzurpator]

Buy both, see which one you like most. Than learn that it does not matter all that much and wear them both out.

I found out that in spring I prefer lighter gears than in the fall, which makes sense, that after a season of riding there is a little more stamina to be used.

 

[Prognosticator]

I like the challenge of climbing but I'm no good at it. I use 28 oval. I'm still no good at climbing but a little less no good.

 

[OneTrustMan]

I'm buying parts for my next bike and can't decide on a 30T or 28T chainring. Factors contributing to the struggle:

• I'm going from 175mm cranks to 165mm. Shorter = less torque = harder to push?
• Want to try an oval chainring instead of round. The downstroke part is the wider part right? So harder to push?
• Hoping to get an Advent X drive train instead of Eagle. My usual climbing gear is the 42 tooth, 50 for steeper hills. Advent X is smaller at 40 and 48.

According to gear-calculator.com a 48T cassette with 28T chainring is slower than 50T with 30T chainring. But that doesn't consider shorter cranks or oval. My goal is to keep the difficulty/speed as close to what I currently have. Thoughts?

I use a 30t oval and a 28t round on 2 bikes with 10-42 cassettes. The oval 30t feels not bad, climbing is easy, but that bike is a hardtail (170 mm cranks) and around 2kg lighter than the enduro bike with the 28t chainring ( 165mm cranks).
Honestly, climbing on both bikes feels very similar after I get used to the oval intervals which takes around 5 minutes or so.
Also I can't really tell a difference in feel/torque between the crank sizes, or even the 175mm on my trail bike. Leg strength is more important imo.

I would recommend the 30 oval to you.

 

[bizango]

I say 28t. The small/small combo is one of the least used, but using the lowest climbing gear is common for most folks. Very little downside to having it be a little lower.

 

[PuddleDuck]

If you try the 30T and decide you want the 28T instead, then you won't need a new chain. You may need a new chain going 28->30

 

[milehi]

In a parallel universe, I cant stand that a lot of frames are limited to 34T. I can't tell the difference on the trail between oval and round rings. My current set ups are single speed 34X20 round, full suss 38X9speed round and 34(limited)X11speed oval.

 

[mtnbkrmike]

Assuming this is a FS, I believe a 28 will make the suspension feel slightly less active. Not a bad thing in some cases. A lot of bikes are designed around a 30 tooth ring.

 

[stripes]

Assuming this is a FS, I believe a 28 will make the suspension feel slightly less active. Not a bad thing in some cases. A lot of bikes are designed around a 30 tooth ring.

I’ve found the opposite in most cases: the smaller than 30t, the more active the suspension gets under power.