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28T chainring with 12 Speed drivetrain?

March 5, 2019, 8:55 a.m.
Posts: 1102
Joined: Sept. 30, 2006

I forgot to mention mine is a 28T oval.  To be honest, I dont really feel that much of a difference.  Perhaps if I went back to a round ring, I would appreciate the effects of an oval ring more.

March 5, 2019, 10:11 a.m.
Posts: 1198
Joined: May 23, 2006

Posted by: Bull_Dozer

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?

I run a 26t AB oval on a RF d/m. 

The AB ring has moar dish than the RF ones and the chain doesn't unship from the big cog when backpedaling like it did with the RF ones.


 Last edited by: tungsten on March 5, 2019, 4:38 p.m., edited 1 time in total.
March 5, 2019, 2:50 p.m.
Posts: 1055
Joined: Nov. 21, 2002

I've got 28t oval with 11-46 on a 29 hardtail. I found the oval to make a notable difference in climbing traction because that's a bigger issue for hardtails. I'm still running 104bcd cranks so the 28t is mounted to the granny tabs, which makes my chainline functionally improved as well.


 Last edited by: UFO on March 5, 2019, 2:52 p.m., edited 1 time in total.
March 5, 2019, 8:55 p.m.
Posts: 171
Joined: April 15, 2017

running a 28t on an 11spd 11-50 sunrace. I don't really use the 50 sprocket unless my legs are hugely gassed and I just need to spin out slowly for recovery. 

It's good that it's there for my pitiful fitness on long grinding climbs but I've not found it useful on any form of technical climb as it spins out way to easily an doesn't really provide the torque/power needed to blast up climbs like Wardens. I'm slowly moving towards a 30t or 30 oval then hopefully move to the 32t if my fitness goals succeed this year.


 Last edited by: DanL on March 5, 2019, 8:58 p.m., edited 1 time in total.
March 5, 2019, 8:57 p.m.
Posts: 199
Joined: May 11, 2018

What size wheels? What size tires?

You can't just say a universal chainring size for all bikes is ok. On a 27.5 I wouldn't go smaller than a 28x42 which is what my wife had when we lived in Nelson (those were some steep ass climbs!). On a 29er I have run a 26x42 and wouldn't go much smaller than that as, like mentioned by someone else, it is too low with too much torque. 

28x50 works out to 16.51 chain inches. This is equivalent to running a 22 or 23 tooth ring with my 11 speed setup. That is a pretty ridiculous gear. to give a frame of reference, back when I used to have a triple front ring with a 22 tooth granny and a 32 tooth cog, that was 20.35 chain inches, but again, that was a 26" setup. Tire size is important but I think I am safe to say, 28x50 is a pretty useless gear. 

I would say that on a 29er the smallest ring I would recommend is a 30 and on a 27.5 a 34.

March 5, 2019, 9:12 p.m.
Posts: 103
Joined: June 17, 2016

http://ritzelrechner.de is helpful to compare gears across different tire sizes

March 6, 2019, 5:18 a.m.
Posts: 18
Joined: Dec. 1, 2008

Also keep in mind that some frames will have clearance issues with the chain on the smallest cog when using small chainrings. Might want to check that beforehand.

March 6, 2019, 8:57 a.m.
Posts: 1
Joined: Jan. 13, 2018

I think a 28T chainring on a 29er is perfect for a not so strong rider, that granny gear comes in handy on a long  climb with no break when your legs are are really feeling it, you can always shift up if it is to low, but it is always there when you need it. I run an Absolute Black oval 28T and love it, the oval shape gives your legs a break at the top of the pedal stroke [great for the not so strong rider] also you get more traction when climbing on loose surfaces, works especially good with Flat Pedals.

March 6, 2019, 10:38 a.m.
Posts: 911
Joined: Feb. 5, 2011

I think I am going to give the 28T oval a try.... worst case scenario I just end up using the 2nd & 3rd gear for most of my climbing. Not worried about the high end of the cassette at all so I don't see much of a downside. There will definitely be some places where the 1st gear comes in handy for me. Planning on riding LOTS for the first time this summer and I assume it will come in handy there. Also good for a few of the steeper sections on the Fromme climb trail when I am running out of gas.

March 6, 2019, 10:56 a.m.
Posts: 3458
Joined: Dec. 17, 2003

Posted by: RAHrider

What size wheels? What size tires?

You can't just say a universal chainring size for all bikes is ok. On a 27.5 I wouldn't go smaller than a 28x42 which is what my wife had when we lived in Nelson (those were some steep ass climbs!). On a 29er I have run a 26x42 and wouldn't go much smaller than that as, like mentioned by someone else, it is too low with too much torque. 

28x50 works out to 16.51 chain inches. This is equivalent to running a 22 or 23 tooth ring with my 11 speed setup. That is a pretty ridiculous gear. to give a frame of reference, back when I used to have a triple front ring with a 22 tooth granny and a 32 tooth cog, that was 20.35 chain inches, but again, that was a 26" setup. Tire size is important but I think I am safe to say, 28x50 is a pretty useless gear. 

I would say that on a 29er the smallest ring I would recommend is a 30 and on a 27.5 a 34.

I think some folks just hope that by dropping the gear inches, climbs will stop sucking as much. They don't, the suck just goes on for longer.

When a climb is sucking and my legs are hurting i try and remember that this is exercise, not sitting on the couch. 

Re: Your numbers - the last multi ring drivetrains that people were probably running were Dynasys - 10 speed 24 cring*36 cassette on 27.5 or 26" wheels. For 26" that gives 17.33" so the 16.51" of 28*50 is not unreasonable viewed in that light.

I definitely walked up hills on a 24*36*26" that I now ride in a higher gear, and to date my fastest time locally on a climb is still the one i did on 32*36*26. We sink to the level of our training.

OP: Do it; ride more walk less!

March 6, 2019, 11:10 a.m.
Posts: 889
Joined: Nov. 23, 2002

Posted by: nouseforaname

I think some folks just hope that by dropping the gear inches, climbs will stop sucking as much. They don't, the suck just goes on for longer.

the best thing about pushing yourself a bit more is that the climbs get easier and suck less as you get better even though you're actually putting out more effort at the improved pace. pushing hard when you're fit is way easier than pushing hard when you're not.

March 6, 2019, 11:47 a.m.
Posts: 14351
Joined: Nov. 20, 2002

I do remember being able to feel "bio-pace" but I didn't really notice the oval thing on an absolute black 28T, I dropped a couple of teeth because I needed a "granny gear" where I ride

I didn't feel I needed a granny  when I demoed the bike on slightly mellower steeps

so I think needing a 28T might depend on where you ride.

Besides you can always just climb on the second rear cog if you really feel the need to suffer

March 6, 2019, 2:24 p.m.
Posts: 699
Joined: March 18, 2017

My best climbs were 32t/11-36 10spd 29er. 

Le sigh 😔

March 7, 2019, 4:45 a.m.
Posts: 16
Joined: Aug. 13, 2017

Posted by: syncro

Posted by: nouseforaname

I think some folks just hope that by dropping the gear inches, climbs will stop sucking as much. They don't, the suck just goes on for longer.

the best thing about pushing yourself a bit more is that the climbs get easier and suck less as you get better even though you're actually putting out more effort at the improved pace. pushing hard when you're fit is way easier than pushing hard when you're not.

Climbs don't get easier they just take less time.  They still hurt.

March 7, 2019, 9:33 a.m.
Posts: 911
Joined: Feb. 5, 2011

Any of you guys have the OneUp Switch chainring system? Seems to be roughly the same price as a regular chainring so seems like a no brainer to me. Anyone with experiences?

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