39 or 42 on SRAM XO 2 x 10

[Viking1]

Hi guys,

 

just bought a Specialized 29'er with 2 x 10 XO's (26/39), I feel like I am running out of gears on the flats, the dealer is telling me 42 will be too heavy.

Any comments??

[jannosmit]

i also thought about this. it feels like you are running out of gears but then again your speed is not that slow, but yes it feels like your are able to go even faster.

 

from a mathematical perspective:

 

if you use a starting point of a 26er with a 42/28 combo, say you keep the same cadence ie 90rpm

-a 26er wheel circ is 203cm, a 29er is 230cm, thus (230-203)/203= 17% faster for 29er

-42vs39 (39-42)/42= -7% 39 7% slower

winner 29er

 

this means that at the same cadence a 29er with 39blade is faster than a 26er with a 42blade, but it still feels you can go bigger/faster with a 29er. please correct me if i'm wrong

 

sorry for the hi-jack viking!

[brussel]

I ride a 29er with a 38 tooth blade and never have problems and I race and ride pretty quick for what it's worth

39 is definitely the winner

[vwyngaardtq]

I also have the 39T and find it to slow, I think 42 with 36 in back will give more than enought power...

[Shebeen]

http://software.bareknucklebrigade.com/rabbit.applet.html

 

39x11 with 29in wheels @90rpm = 45km/h

almost the same as 44x11 with 26in

 

how fast do you need to pedal on the flats?

[Viking1]

http://software.bareknucklebrigade.com/rabbit.applet.html

 

39x11 with 29in wheels @90rpm = 45km/h

almost the same as 44x11 with 26in

 

how fast do you need to pedal on the flats?

 

Havent checked the cadence, but fast compared to my partner on a 26' 3 x 9, I will give the 42 a try and see whether better or not.

cheers

[Viking1]

i also thought about this. it feels like you are running out of gears but then again your speed is not that slow, but yes it feels like your are able to go even faster.

 

from a mathematical perspective:

 

if you use a starting point of a 26er with a 42/28 combo, say you keep the same cadence ie 90rpm

-a 26er wheel circ is 203cm, a 29er is 230cm, thus (230-203)/203= 17% faster for 29er

-42vs39 (39-42)/42= -7% 39 7% slower

winner 29er

 

this means that at the same cadence a 29er with 39blade is faster than a 26er with a 42blade, but it still feels you can go bigger/faster with a 29er. please correct me if i'm wrong

 

sorry for the hi-jack viking!

 

Thats excactly the point, I am going fast but feel like I can go faster, my medical aid might appreciate staying at 39

[jcmeyerSS]

I recently bought XO 2x10 i feel the same and i'm on a 42 up front. fair enough i"m riding a 26" spez. but my riding partner just recently bought a Niner with XT 10 speed. this all happened around the time and pre-10 speed i would kill him on those long flat sections (eg the ride to/from breedts) now when I'm flat out he can cruise past me with his 44t on the 29" wheels.

[Paulst12]

I have the XTR 2X10 on my 29er HT.

Front is a 44/30

Back is a 11/36

 

No problem climbing the steepest hills on Sani2C, and with the marathon races we have here the 44 / 11 flies.

 

With a 39 in front you are going to struggle to stay with guys running a 42 unless you have great cadence.

Edited June 12, 2011 by Paulst12

[Witkop]

Ok I have a single speed and am running a 32x16 gear ratio on a 26 inch wheel. on the flats I am running out of gears and on the climbs I have to stand to pedal over the hills. What should I do?

 

a. change to 32 x 14 an push harder on the hills?

b. change to 32 x 18 and free wheel on the flats?

c. learn to ride with increased cadency on the flats and more power on the hills?

d. Buy a 29er 10xspeed dual suspension carbon fibre bike to bolt onto the back of my luury 4x4?

[Edge_Design]

On a similar topic, how much will it cost for a 42 chain ring for X0? I also have 26/39 and really need the 42...

[Bat-ass]

Your answer lies with Shimano..... 10 speed dynasys!!! 24 36 42 up front... klaar!!!

[SirJody]

On some of those long distance rides, like Trans Baviaans, the bigger blade comes in handy for more than 120km's. The smaller one is essential too on then climbs and then of course you do need that middle balde from time to time. So why not just stick with 3 blades upfront? Is there any disadvantage besides a few extra grams?