3x9 to 2x10 considerations

hard-rider

I currently ride a 3x9 (44/32/22 - 32/11) setup on my 26". I'm getting ready to build a 29er and am considering going to a 2x10. I occasionally have to drop down to the 22Tgranny gear on my 3x9 and often use the 44T when road riding so want to get as close to those extreme ratios as possible. From the gear ratio calculator on Sheldon's site the 38/24 - 36/11 setup seems to come closest to the ratios I'm used to riding.

So with 2x10 is cross chaining an issue? Is it OK to ride the full cassette on either front ring without accelerated chain wear and chain rub issues?

Would I require a long cage rear derailleur?

What's the difference between the Shimano Shadow and Shadow +?

Chunkers1980

Extremes in chain line will always cause more problems than straighter ones.

Shadow + has a clutch on the pulley arm to reduce chain slap.

lostboysaint

No it isn't.

Chunkers has the differences right.

A 14 tooth jump is quite a lot on the front. Do you REALLY need to gear the bike with a 38? I'd go 36/24 and a 36/11 for the amount of time you'd actually need the "big" road gear. Just get used to spinning a bit faster.

hard-rider

Thanks. I'll have to think about it some more then. On the point of REALLY requiring the 38:- On the return from a few of the trails I ride I have long descents down roads on which I spin out with my current 3x9 44/11 setup. But if a 14T jump is going to cause problems then I'll make the compromise or alternatively go with a 3x10 setup.

The Rookie

Do you REALLY spin out, or does it just feel like it, I know a single speeder who hits 160rpm on the cranks on downhills.....

lostboysaint

If they are that steep, why bother pedalling at all?!

And I'd ask the same question as The Beginner. There's a number of singlespeeders who ride with us that regularly hit 150rpm+ on 32/16 or 34/17 on 26" wheels, which is plenty quick enough on most roads.

hard-rider

160rpm! I don't know what rpm I'm getting to but it starts to feel uncomfortable and unstable once I get above 50kph. I feel like I'm starting to bob on my seat. The hills are long and fairly shallow so if you stop pedalling your speed drops off a lot hence for the tall gearing required. It's not really a major issue and I'm sure I'll get used to it if I go for the 36T.

Was more concerned about the cross chaining on a 2x10 and the 14 tooth jump on the front rings.

bernie1973

Surely 38/24 won't be too much of an issue. After all, shimano sell them...
http://www.chainreactioncycles.com/Basket.aspx

hard-rider

That's what I was thinking until lostboysaint mentioned the large jump. Thinking about it, I guess it's not going to be the most elegant of shifts and you'd have to compensate with shifting two cogs at the back otherwise it's going to be a huge jump in ratio.

Chunkers1980

Which is the reason I prefer triples. Middle for most and big and gran should you feel the need.

felix.london

Does sound like sticking with a triple would be best for the OP

Maro

My current (very old) ride is a hardtail on a single front ring ,either 38 or 40 tooth, and nine speed cassette, 11/32. It's not the easiest thing for offroad climbing but it's fine otherwise, I used to use it for everything, inc downhill and for the road. Thinking about putting 2 rings on whatever buy next, I'm returning to the sport.

hard-rider

OK, I've officially become anal :oops:

I've run the various 2x10 combos through the Sheldon gear calculator against the 3x9 I currently have and my conclusions are that if I use a 38/24 then I'm not losing much at the top end (~2.5kph @ 120rpm). The 3x10 would give me about 4kph over the current 3x9. On the bottom end there is no difference between the 3x10 or 2x10 (if I use the 38/24) which is not too far off the 3x9 I current have.

So for the sake of simplicity and marginal weight saving I'm starting to think that I'll sacrifice the top end of the 3x10 and adjust my riding style.

the only issue I see is the larger gaps between gears with the 2x10 38/24 - 36-11 set up

hard-rider

cyd190468 wrote:

2x10 will be fine if you use 24/38. You lose roughly one gear at each ench. Mine is sram and I have no trouble with the front shifting. The chainline is set so you basically use it as a 1x10 on the 38 until you come to a big climb then you drop to the 24. 24/38 with a 11-36 cassette is the most common 2x10 setup over here (Australia), for 29ers anyway.
Welcome to the 21st century

I didn't think of it like that. I for some reason assumed you ride on the smaller ring most of the time but what you say makes more sense.

lostboysaint

Not at all, you do pretty much everything on the big one. My full sus (26) runs 2x9 and is 39/27 with an 11-34 cassette and is pretty much unstoppable. The 29er is a 1x9 and runs a 32 chainring and a 12-36 cassette and offers pretty much identical gearing to a 26 with 34 and 11-34. It's rarely over or undergeared.

felix.london

Over here it's the best set-up as you use the small ring to climb and the big (middle) ring to descend...nice and simple - downs are normally to steep or techie to require peddling anyway so (proper) big ring is not missed one bit

bails87

Just FYI, I use a 24/38 combo (with a 11-34 cassette) and the front shifts just fine. Use a dedicated 2 ring front mech though, I kept dropping the chain when I used a 3 speed one.

hard-rider

bails87 wrote:

Just FYI, I use a 24/38 combo (with a 11-34 cassette) and the front shifts just fine. Use a dedicated 2 ring front mech though, I kept dropping the chain when I used a 3 speed one.

Thanks for the input. I'm starting to lean more to the 38/24 now with dedicated direct mount 2x10 front mech.

simowill

I'm currently running 38/24 and 11-36. Find the climbs fine but spin out on some of the longer downs around the Purbeck's.
front shifting is fine.

Simon