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28T chainring with 12 Speed drivetrain?

March 4, 2019, 3:03 p.m.
Posts: 911
Joined: Feb. 5, 2011

Recently got a new bike that came with SRAM GX Eagle 12 speed drivetrain and it came with a 32T chainring... which is fine in general but my fitness isn't the greatest and can use all the help I can get for climbing. Looking to get a slightly smaller chainring... trying to decide between a 28T or a 30T (likely oval). Are any of you running a 28T with a 12 sp cassette? Is it too small? I don't care about losing out on the higher end since I'm rarely pedaling at full speed anyways.

March 4, 2019, 3:47 p.m.
Posts: 3455
Joined: Dec. 17, 2003

One of the guys i ride with resorted to that for the chilcotins. He didn't have any issues.

It may put the chain below your suspension pivot and that may change how your suspension works/feels under pedalling. 

I put a 30t chainring on my Slash and felt it was less comfortable when climbing.

March 4, 2019, 3:57 p.m.
Posts: 1043
Joined: Feb. 26, 2015

Personal preference. I have 30T x 12 on both bikes. I prefer it, most people I ride with have 28T. Like you say your fitness isn't the best then go for the 28T

March 4, 2019, 3:58 p.m.
Posts: 1102
Joined: Sept. 30, 2006

Id say you might also have to worry about having too much torque in the easiest gear.  My wife runs a pretty small front ring and finds that she spins out on anything that is too steep and loose.

March 4, 2019, 3:59 p.m.
Posts: 370
Joined: Jan. 31, 2005

So your lowest gear would be a 28x50?? That's really low.

March 4, 2019, 5:19 p.m.
Posts: 888
Joined: Nov. 23, 2002

Posted by: craw

So your lowest gear would be a 28x50?? That's really low.

I decided to stick with the double on the new bike and went 32/22 with a 52T in the back - should be able to climb up the grind if I want.

March 4, 2019, 6:24 p.m.
Posts: 1194
Joined: May 23, 2006

Posted by: syncro

Posted by: craw

So your lowest gear would be a 28x50?? That's really low.

I decided to stick with the double on the new bike and went 32/22 with a 52T in the back - should be able to climb up the grind if I want.

Typo?

March 4, 2019, 6:43 p.m.
Posts: 888
Joined: Nov. 23, 2002

Posted by: tungsten

Typo?

https://www.aliexpress.com/w/wholesale-11-52t-cassette.html

March 4, 2019, 7:24 p.m.
Posts: 137
Joined: Jan. 2, 2018

Another consideration is how much top end do you need? I have a 30t oval on my 27.5 bike and a 28t round on my 29er. They work out to feeling pretty similar.

Both bikes top out around 45kph (on Seymour parkway on my way to the trailhead, I can't hit 45kph on any trail I've ridden on the shore. I don't commute with them and I'm not training to enter world Cup downhill events, so that's fast enough for me. Anyone telling you they are regularly exceeding 40kph in North Shore trails, and not only that but also needing to pedal while doing 40kph is a god level rider (or full of it).

I say do it for sure. As fitness improves you will use the 50t less. Imo Eagle works well if it's setup so you use 2nd and 3rd gear for most climbing and the 50t is a bailout gear anyways.


 Last edited by: Kenny on March 4, 2019, 7:25 p.m., edited 1 time in total.
March 4, 2019, 7:38 p.m.
Posts: 14351
Joined: Nov. 20, 2002

I put a 28T absolute black on the yeti with a 11-46 cluster, I think I had to remove a couple of  links if memory serves

I have an Aeffect crank with a splined interface which allows small chainrings

so a good question is will your front crank take a 28  ?

March 5, 2019, 7:16 a.m.
Posts: 911
Joined: Feb. 5, 2011

Posted by: XXX_er

so a good question is will your front crank take a 28  ?

It's direct mount so I assume there shouldn't be a problem, right?

March 5, 2019, 7:19 a.m.
Posts: 911
Joined: Feb. 5, 2011

Posted by: craw

So your lowest gear would be a 28x50?? That's really low.

Yeah for sure... my plan would be to mainly be using the 2nd and 3rd gears for climbing (as Kenny mentioned above) and then use the 50 only in limited situations when it is really steep or if I need a break but still want to keep moving.

March 5, 2019, 8:09 a.m.
Posts: 101
Joined: June 17, 2016

I went from a 30T to a 28T last year and I love it, but this is with 11-speed and 11-42 cassette (on a 27.5). 28x42 is plenty low for me, any lower and it's faster to walk I think!

It really made a difference for me, I feel less tired and it makes a 2nd or 3rd lap easier.

March 5, 2019, 8:18 a.m.
Posts: 1102
Joined: Sept. 30, 2006

I have my 11 speed setup with a 28T and an 11-47 cassette (27.5). I usually try to do most of my climbing in the 37t and 42t but definitely find the need for the 47t on the low energy/lazier/steeper days.


 Last edited by: shoreboy on March 5, 2019, 8:21 a.m., edited 2 times in total.
March 5, 2019, 8:43 a.m.
Posts: 911
Joined: Feb. 5, 2011

Thanks for the input guys. Sounds like its worth trying the 28T.... would 28T oval be weird?  Isn't the way it works that it would feel like a 26T and a 30T depending on what part of the chainring you are using? I previously had a 30T oval on my old bike and I liked it.

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