29er chainset

h8ch

Hi I'm starting to upgrade my carbon scale 29er I was wondering when changing the chainset if to go for a 2 x 10 as its got a 3 times 10 at the moment.
I will be using it mainly for 24 h events such as mayhem, sleepless etc so could do with some info on chainring/rear cassette sizes etc .
I'm six three and around 14 stone and ride a single speed a lot so dont mind pushing gears,any info would be welcome cheers.

Anonymous

Don't know specifically about a 29er, but I'm quite sold on 2x10 for what I do (anything down, singletrack, climbs if I have to, but don't do events or races). It's got much of the range of a 3x9 in two cogs which makes things simpler and less problematic with front shifting, and the 2x10 has little cross over of gear ratios.

More so as I've got 26/39 up front which means both rings are viable for a range of gears instead of the little being a granny ring I only drop into on steep climbs. With my old 3x9 the big was never used, and the granny got limited use, more so as I got fitter. I can go 1x, and indeed have on my hard tail but there's extra effort required on the climbs and slightly lack on the top end, but does fine for the hard tail being a light carbon rig. The 2x10 just gives more range for an all mountain rig I find for all kinds of terrain.

Have a play: http://sheldonbrown.com/gears/

With that you can fiddle with all the combinations and work out the gear ratios you get, and compare it to what you've got.

baznav73

2 x 10 is great and have been useing it for 8 months and i hate riding bikes with three front rings now, i have the 28/42 which is fine.

The Rookie

deadkenny wrote:

With my old 3x9 the big was never used,

So effectively you ran 2x9 anyway!

Simon

nicklouse

TBH get onto Sheldon site and find the gear calc and put in some info as see what it gives as you know what you have been using and what you think you can drop.

As of now I would say the info you are looking for is not really there as the 29ers are still"new" and the users on here that have one don't seem to compete with them.

Good luck.

Anonymous

The Beginner wrote:

deadkenny wrote:

With my old 3x9 the big was never used,

So effectively you ran 2x9 anyway!

Yeah, though not the ideal set up really with 22/32t. The 26/39t on the 2x10 is much more flexible, more so with 10 speed.

That 3x9 crank ended up on the hard tail, has a bash on the big now and a single 34t in the middle, no granny.


As for 29er experience, try american forums. They're nuts on 29ers. 26 seems to be rare there now.

The Rookie

I'm running 2x9 on my MTB, am after a 36T 'middle' ring as yes it occasionaly runs out of gear (22/32 - ideally I'd go 24/36->39ish), I can't see that much benefit from 10 speed as the 34->36t big gear only really gives you another half a gear, certainly not enough benefit to junk everything I have to fit it!

Simon

njee20

You know what gears you find useful and what you can do without.

A lot of manufacturers are fitting the 26/39 SRAM cranks to their 29ers over the 28/42 or 30/42 because of the slightly taller gearing. I'd say the former will cover most eventualities combined with an 11-36 block. If you do anything on the road you may want more top end and something with a 42 may be of more use. You don't say if you do solo 24s - in which case the 'bail out' gears are probably more useful.

Of the folk in my riding group who ride 29ers (we all race) there's one running 36t single ring (with 11-36), and several on doubles - two on 26/39 and one on 26/38. As with 26" wheels, it's personal!

mrmonkfinger

I'm going to have to get me a 24/36 setup. The ratios look golden - one climbing ring, one flats & downhill ring.

Comparing it to a 22/32/42 where I end up with the 22 for the two bail out gears and rarely if ever use 42. 42 only gives two more gears over the 32 ring. The 36 gets one of those gears back and the 24 goes low enough for any climbs. Plus you get to fit a bash guard instead of smacking a pricey gear ring on a rock every so often.

Triples made a lot of sense in the 7 speed days.

Dammit I've talked myself into another kit purchase.

njee20

I'd want bigger than a 36 potentially (although I run a 36t single on 26" wheels), particularly for racing 24s where there are often fast pedally bits. If you don't find yourself struggling at the low end I'd say 26/39 would give you a bit more versatility.

mrmonkfinger

njee20 wrote:

I'd want bigger than a 36 potentially (although I run a 36t single on 26" wheels), particularly for racing 24s where there are often fast pedally bits. If you don't find yourself struggling at the low end I'd say 26/39 would give you a bit more versatility.

42t makes a lot of sense if you're running 24" rims.

njee20

Or have no use for a 24 or 26, in which case a 28/42 is quite a nice double.

The Rookie

42T must be a good budget option, the place is awsh with removed ones from double and bash conversions!

Simon

njee20

Not for SRAM chainsets though sadly - 80/120mm BCD. Nor XTR M985 which is 88, but yes, for XT doubles they'd be good - but then you can buy one off the shelf like that!