39/26 vs 40/28. Should I feel a real difference?

[kandui]

I have an XX 39/26 setup on my Air 9 HT and an XTR 40/28 on my Jet 9 Alu Full Sus. Both have an 11-36 cluster.

No need for ratio graphs here. I want to know whether I should be feeling a big difference in leg power applied or whether my legs are just poked at the moment? I am talking climbing gears. At yesterday's Oude Molen my legs were toast after 60km of riding the XTR rig.

 

Perhaps I should move the XTR to the lighter bike?

[Captain Fastbastard Mayhem]

Those extra 2 teeth do make a marginal difference, yes. It's small, but it's there!

 

Moving the "lighter" crankset to the heavier bike would be logical, due to the extra weight you are pushing up the hills.

 

And there's quite a difference in weight between the Air 9 and the Jet 9 IIRC!

[kandui]

I felt I had to ask. I think I'll move the XTR crank over to the Carbon bike . Probably leg fatigue, a slight cold and the terrain yesterday made it feel so hard to turn the crank over yesterday.

[Ryan]

a slight cold

 

That can make any ride horrible...

Edited August 20, 2012 by Ryan

[Captain Fastbastard Mayhem]

I felt I had to ask. I think I'll move the XTR crank over to the Carbon bike . Probably leg fatigue, a slight cold and the terrain yesterday made it feel so hard to turn the crank over yesterday.

 

I know what you mean... I'm running 1x9 at the moment (32 at the front, 11-34 at the back) and my chain snapped halfway to tokai. Luckily it was just 4 / 5 links away from the quicklink, so a fix was possible (left my chain breaker at home) but I lost my top 2 gears. Eish, I suffered...

[NINER_boy]

Hi Kandui

 

Especially on 29ers, the bigger chainrings need more torque to turn.

 

The recommended size for 29ers is 26/39 and smaller.

 

I have recently moved over to Rotor crank and Qrings on my Niner RIP9, size 25/38.

My bike feels like a nimble little beast.

Yes the Q rings make a difference, not acceleration but more on the power-drive part.

 

Yes my gears are all "shorter" and I top out at around 55km/h, but then again, how much of your time do you spend at these speeds.

 

Go smaller, you will not regret it.

 

PS, this is probably the ONLY instance where going smaller is beneficial...

 

Happy Hoopin

Edited August 20, 2012 by NINER_boy

[kandui]

Hi Kandui

 

Especially on 29ers, the bigger chainrings need more torque to turn.

 

The recommended size for 29ers is 26/39 and smaller.

 

I have recently moved over to Rotor crank and Qrings on my Niner RIP9, size 25/38.

My bike feels like a nimble little beast.

Yes the Q rings make a difference, not acceleration but more on the power-drive part.

 

Yes my gears are all "shorter" and I top out at around 55km/h, but then again, how much of your time do you spend at these speeds.

 

Go smaller, you will not regret it.

 

PS, this is probably the ONLY instance where going smaller is beneficial...

 

Happy Hoopin

I want to go 56km/h uphill.

 

i have been eying the Rotor cranks , but just got the XTR a month ago. Would the Q rings fit either XX or XTR? Would dig to give them a try if anyone has some second hand ones.

[Overlord]

Running 40/27 Rotor Crank on my 29er and it is absolutely awesome.

[Andro]

 

I want to go 56km/h uphill.

 

i have been eying the Rotor cranks , but just got the XTR a month ago. Would the Q rings fit either XX or XTR? Would dig to give them a try if anyone has some second hand ones.

 

Morning Kandui.

 

Running a Rotor system, re your question... not sure but call this no, Burry's dads shop, friendly service and will be able to assist.

 

031 762 1416

 

or speak to Naas here on the hub. He operates from Durbanville. He was selling some new blades.

 

 

Best Regards

 

Andro

[kandui]

Thanks Andro. I had actually spoken to Mr Stander last year about Rotor cranks, but was put off by the price and went for an XX rig instead.

I would however like to try the Q Rings on the XX crank and see what it feels like. Buying new just to try is not what i want to do so I am looking for a second hand set. 40/27 or 38/26.

[Edge_Design]

Definitely a big difference for climbing... I have 42/28 on my Anthem 29er and it was deadly when I first got on it (changed from 26/39). I've gotten used to it now and prefer having the top-end/cruising speed available - the strength will come from training on the bigger gear (all of my training is in Tokai so no shortage of climbing!). If I was doing ultra marathon stuff then the 26 would definitely be necessary, but 60 to 70km's is my max on the MTB.

[Johan Bornman]

Yes.

 

A 29er wheel moves forward 2280mm with every revolution.

 

If you turn the crank in your 39/26 gear once, your bike goes forward 3420mm

If yo turn the crank in your 40/28 gear once, your bike goes forward 3257mm.

 

Thus, the 39/26 gearing is 5% harder than the 40/28 setup. If you're a glass-half-full type of person you would put it differently: the 39/26 gearing is 5% faster.

[NINER_boy]

Hi Kandui

 

The XX BCD is much different from the XTR, so you will need to decide witch ones to get and then buy for that system.

 

Here is a website where I got my cranks and Q rings from...

 

http://www.velotechs...co.uk/index.asp

 

Sram XX BCD is 120/80mm

XTR BCD is 110/74mm

Edited August 21, 2012 by NINER_boy

[NotSoBigBen]

Perhaps just check out Rule #5

[kandui]

Running 40/27 Rotor Crank on my 29er and it is absolutely awesome.

Do you need a longer chain for the Rings?

[kandui]

Hi Kandui

 

The XX BCD is much different from the XTR, so you will need to decide witch ones to get and then buy for that system.

 

Here is a website where I got my cranks and Q rings from...

 

http://www.velotechs...co.uk/index.asp

 

Sram XX BCD is 120/80mm

XTR BCD is 110/74mm

Bought a set of second hand 40/27 Q Rings from a fellow Hubber yesterday. I'll stick them on my XX Crank which is on the Air Carbon.

Doing a ride from Grabouw to Greyton on Sunday, that should give me enough time to get used to them and evaluate.

If I like the Q Ring, I will probably go one smaller, because I spend more time climbing than I do on the flat roads.