Chainring 34T vs 36T oval

[NotSoBigBen]

19 minutes ago, Lukas Ferreira said:

Lastly

offset

0mm , 3mm or 6mm

non boost rear 

To my knowledge boost 3mm, non boost 6mm ... then again no idea what '0mm' is for ... luckily there are cleverer okes on here than me that'll soon help om sure 😎

[DieselnDust]

Non boost is 6mm

0mm is for 55mm chainline bikes or for cranks with the offset built in.

cannondale hollow gram chainrings for example are 0mm offset because the offset is built into the Ai axle

[ChrisF]

23 minutes ago, NotSoBigBen said:

To my knowledge boost 3mm, non boost 6mm ... then again no idea what '0mm' is for ... luckily there are cleverer okes on here than me that'll soon help om sure 😎

 

Some things I ask my LBS to help with ....🙈

[dasilvarsa]

Go for 34 Tooth Round

[Me rida my bicycle]

I would also say 34 round. I used to like oval but found I am actually faster on round. I have some 32 and 34 6mm sram blades if you want to test. 

[ratherberidin']

I started using an oval by accident and wont go back to round. It’s marginal though, not alles. If you’re dik fris, go 36. If you’re a normal oke like me who is maybe dik fris bit still working on it, go smaller! I use 32 equivalent. 

[swingTOpeddle]

@Lukas Ferreira do you know your w/kg? I watched a YouTube video a while ago and the discussion said under 4w/kg a 32 will probably be most beneficial. 

[NotSoBigBen]

My last 2c on this subject .... With a 1x whatever chainring you decide it'll be a compromise.

Takes hat and coat ....

 

 

 

 

[DieselnDust]

32 minutes ago, NotSoBigBen said:

My last 2c on this subject .... With a 1x whatever chainring you decide it'll be a compromise.

Takes hat and coat ....

 

 

 

 

this is true.

The watt / kg is a good guide to minimise the compromise.

In the inland area guys like to fit a chainring 2T bigger than at the coast. Coastal is more mountainous but inland also has some big rollers but there's more flat pedalling. 

When I look at the pro ladies bikes,these are mostly fitted with 34T chainrings for longer rides/races and 36T for XCO (>4.5W/kg). The men 36T for longer races and 38T for XCO (>5W/kg)

Most amateurs over gear their bikes at the top end. If you can't sustain the 34 x10 for more than 8min without  blowing up at 85 to 95rpm then the bike is overgeared.

Hence for a novice just building a bike (I assume first MTB) I assume a 32T will be the ideal starting point and will allow good low range gearing for climbing techy trails.

 

Off to ride

[guidodg]

32T

[Christie]

AFAIK oval rings have been proven to be ineffective - they came back into fassion when power meters became more common. Older power meters had a lower data sample rate, and some of these measured more power for oval rings. Modern meters allow higher sample rates, resulting in zero nett benefit from an oval ring.

[madmarc]

I run 1 X with 10/52. had a 34 oval for years - I suck at climbing. when i started training hills for TB and analyzing my gear use on AXS app i was in my 52 on climbs for most of the time - I had no more gears if i started blowing on a climb which was often (training at SBR) 

Changed to a 32 oval - which enabled me to stay in the 42 on the same climb - the app indicated i was in the 42 for nearly the same time as i was in the 52 using a 34 oval - But now i had the 52 to go to when i started blowing. I reality my perceived exhaustion was lower, I never had to stop and I climbed about 9 or 10 % faster. I don't spin out on the flats and by the time i spin out on the downhills, i'm doing speeds which i wouldn't want any faster especially on off-road descents. So i just freewheel. In fact on the descent of Bergplaas i had to wait for my team mate riding a 34 who was a lot stronger than me. 

This is actually the intention of the SRAM 10-52. the top 11 gears are your riding gears with the 52 being your bailout gear on steep and tech climbs so if you find you in your 52 on most of the climbs then drop your chainring size.

Selecting a gear ratio has a lot to do with what type of rider you are - some riders can ride at a high cadence easy gear and others have to ride at lower cadence harder gear but both climb at the same speed - so you would need to test which is best for you on the same climb - My next test will be the 30 oval maybe i will suck less on climbs

Edited December 11, 2022 by madmarc

[openmind]

6 minutes ago, madmarc said:

I run 1 X with 10/51. had a 34 oval for years - I suck at climbing. when i started training hills for TB and analyzing my gear use on AXS app i was in my 51 on climbs for most of the time - I had no more gears if i started blowing on a climb which was often (training at SBR) 

Changed to a 32 oval - which enabled me to stay in the 42 on the same climb - the app indicated i was in the 42 for nearly the same time as i was in the 51 using a 34 oval - But now i had the 51 to go to when i started blowing. I reality my perceived exhaustion was lower, I never had to stop and I climbed about 9 or 10 % faster. I don't spin out on the flats and by the time i spin out on the downhills, i'm doing speeds which i wouldn't want any faster especially on off-road descents. So i just freewheel. In fact on the descent of Bergplaas i had to wait for my team mate riding a 34 who was a lot stronger than me. 

This is actually the intention of the SRAM 10-51. the top 11 gears are your riding gears with the 51 being your bailout gear on steep and tech climbs so if you find you in your 51 on most of the climbs then drop your chainring size.

Selecting a gear ratio has a lot to do with what type of rider you are - some riders can ride at a high cadence easy gear and others have to ride at lower cadence harder gear but both climb at the same speed - so you would need to test which is best for you on the same climb - My next test will be the 30 oval maybe i will suck less on climbs

SRAM is either 10/50 or 10/52

Shimano is 10/51

I prefer the Shimano ratios, they don’t have the “bail out” gear philosophy, the ratios are spaced out more evenly so you can use the whole block. 

[madmarc]

36 minutes ago, Christie said:

AFAIK oval rings have been proven to be ineffective - they came back into fassion when power meters became more common. Older power meters had a lower data sample rate, and some of these measured more power for oval rings. Modern meters allow higher sample rates, resulting in zero nett benefit from an oval ring.

In theory I agree, there is no power advantage proved with Oval over round. However when i changed I found my climbing or pedal stroke was smoother and i was more comfortable and perceived exhaustion was lower - I wasn't mashing my pedal strokes like i did on the round - so for me oval is better, instead of puking up a lung halfway up the climb i puked it up near the top, but it never made me faster.

[madmarc]

6 minutes ago, openmind said:

SRAM is either 10/50 or 10/52

Shimano is 10/51

I prefer the Shimano ratios, they don’t have the “bail out” gear philosophy, the ratios are spaced out more evenly so you can use the whole block. 

Ooops I changed it - my ratio is SRAM 10/52 dunno why i had 51 in my kop while i was typing 

[100Tours]

Personally:

34t for a 29er, 36t if you're on a 650B

If you have a 12s groupset then you can go up a size. i.e. 36t on a 29er.

I like my ovals - they will make a difference if you are a seated climber, otherwise round is also perfectly good.