[bikebabe]

Need help with either tweaking on my drivetrain or realizing that my problem with it is normal. I'm running 29 and 44 rings on front and 9 speed cassette in back. The front derailleur and shifter are the normal XT that can also be run with 3 rings.

Basically what's happening is that I can only use about half of the gearings without the chain rubbing on the front derailleur. Big ring in front, little ring in back till about the middle ring in back and small ring in front, big ring in back again till about the middle ring works fine. If I go outside this range like small ring in front and a smaller ring in back, the chain rubs. I've tried tweaking the limit screws and the barrel adjuster but haven't hit the sweet spot. I realize it's not smart to use big ring/ big ring or little ring/little ring but I'd like to be able to use a few more gears. Do I keep trying or is this a normal thing with a 2x9 drivetrain? Any hints? It's getting frustrating!!!!:angry:

Thanks in advance for any advice

 

[Echo]

Also you might want to check:

That the front derailleur plate is parallel to the chain.

That the front derailleur vertical position (where it's physically clamped to the frame) is right.

Both of those things could cause rubbing. You should be able to get most of your gears with that setup.

 

[indieboy]

i've been running a 2x9 for a very long time and it's impossible to not get any chain rub. b/c you have to crosschain to get the most out of your gearing. so don't bother w /trying to get it not to rub b/c it's going to, sorry but that's just how it is

 

[The Toninator]

thats kind of a weird chainring size (29). but it seem like if you pulled the BB lenght in you should be able to use all the gears. (Maybe expirement with that some)

 

[indieboy]

Originally posted by The Toninator
thats kind of a weird chainring size (29). but it seem like if you pulled the BB lenght in you should be able to use all the gears. (Maybe expirement with that some)

nope it still gonna rub a little bit. running a tighter bb length helps a 2x9 out a lot b/c it will help the chain line out but it's still gonna rub. and a 29 is actually pretty normal for a 2x9

 

[bikebabe]

Thanks for the detailed responses. With all your advice, I fixed it up so that there is still some but much less chain rub. It's finally acceptable for most gears.

I'd rather not buy new shifters right now but I'll keep it in mind for the next time "upgraditis" hits....and that happens way too often!

Thanks again!

 

[indieboy]

Originally posted by bikebabe
Thanks for the detailed responses. With all your advice, I fixed it up so that there is still some but much less chain rub. It's finally acceptable for most gears.

I'd rather not buy new shifters right now but I'll keep it in mind for the next time "upgraditis" hits....and that happens way too often!

Thanks again!

do you have a c'dale by chance? b/c if you do you realllllllly need to get rid of the chain rings they supply on their cranks. those chain rings are awful. not to many companies make a decent 29, but there are quite a few companies you can get a good replacement 44 from.

 

[bikebabe]

Originally posted by indieboy


do you have a c'dale by chance? b/c if you do you realllllllly need to get rid of the chain rings they supply on their cranks. those chain rings are awful. not to many companies make a decent 29, but there are quite a few companies you can get a good replacement 44 from.

Yup it's a cannondale. Being rather ignorant about c'dale parts, what's bad about the chain rings? Any companies you'd recommend that make good 29's or is it worth going back to a 3x9 set up for better quality parts (without sacrificing too much weight)?

 

[indieboy]

Originally posted by bikebabe


Yup it's a cannondale. Being rather ignorant about c'dale parts, what's bad about the chain rings? Any companies you'd recommend that make good 29's or is it worth going back to a 3x9 set up for better quality parts (without sacrificing too much weight)?

the c'dale rings just wear out quickly and don't shift worth a damn b/c they aren't machined well. vuelta(sp?) makes a pretty damn good 29, that's about the only one though.

 

[CTR]

what is the major advantage of running 2x9, is it just a weigh thing? or does it help chainsuck?

 

[Echo]

You get a small weight advantage, and many people do not have a need for a granny gear on a racing hardtail.

 

[bikebabe]

Originally posted by CTR
what is the major advantage of running 2x9, is it just a weigh thing? or does it help chainsuck?

For me, the main advantage is that I have to shift less up front---less chance of something breaking. While I can fix my bike if something goes wrong, roadside repairs are not my strength since I can't carry along Zinn and the art of mtn bike maint.

From http://www.light-bikes.com/articles/drivetrain.htm

This setup is common among cross country racers and comes stock on a small number of bikes. There are several places where you save weight:

No more (steel) granny ring! -40g
No more bolts for the granny ring: lose 15-20g
Middle ring reduced from 32t to 29t: 7-15g
Shorter BB: 5-10g
Next to saving weight, there’s another advantage: you’ll do a lot less shifting up front, where drivetrain mishaps often occur. The downsides of this system are the increased difference in gear ratios, and the slightly reduced granny gear. Effectively, you’ll be missing the last one or two cogs off your current setup.

 

[indieboy]

Originally posted by CTR
what is the major advantage of running 2x9, is it just a weigh thing? or does it help chainsuck?

it's just a personal preference. i run it b/c i like to mess around w/ different gear ratios. i don't do it so much for weight savings. b/c it's not all that much of a difference. plus w/ the 9 speed, and a 34 you don't really need a granny gear.

 

[Joe Pozer]

I also have a 2 x 9 set up on my bike (c-dale) and with a Shimano front shifter you will always get a small amount of chain rub. The idea about using a SRAM front shifter is actually a good one. That would allow you to trim the front derailleur to avoid the rubbing. I may have to try that...

Indie, you are absolutley correct about the C-dale chainrings...they totally blow. I have to replace my chainrings every year because the wear out so quickly. You say Vuelta makes a 29? I'll have to try them out and see if the ring will last a little longer.

 

[indieboy]

Originally posted by Joe Pozer
I also have a 2 x 9 set up on my bike (c-dale) and with a Shimano front shifter you will always get a small amount of chain rub. The idea about using a SRAM front shifter is actually a good one. That would allow you to trim the front derailleur to avoid the rubbing. I may have to try that...

Indie, you are absolutley correct about the C-dale chainrings...they totally blow. I have to replace my chainrings every year because the wear out so quickly. You say Vuelta makes a 29? I'll have to try them out and see if the ring will last a little longer.

i'm almost positive they do, b/c they have a good decent sizes of different chainrings sizes.

 

[MikeD]

Jeez...29 to 44t?? Shimano fronts can only handle 12t of difference, by the book (or so I'm told). I have enough trouble with my 2-ring 36t/22t setup already!!

I went to an SRAM front and a Shimano trigger rear on both my trail and DH/FR bikes (both of which use 36/22). It helps a LOT, and you can get a set of SRAM shifters from Cambria for about $20 on closeout. The front shifter will work with any shimano mech., regardless of the rear shifter being SRAM (ESP) or Shimano specific.

It also forces me to buy 2 sets of ODI lockons at a time...! Gotta get one set shortie and one set regular, but then I have grips for 2 bikes with no waste in the end.

Actually, a 29/44 combo would be pretty good for me if I start racing DH a lot more...hmmm.... Big Bear spins out your 36t a bit quickly.

MD

 

[MikeD]

Originally posted by The Toninator
thats kind of a weird chainring size (29). but it seem like if you pulled the BB lenght in you should be able to use all the gears. (Maybe expirement with that some)

Basically, you want to make your 2 remaining gears center on where the middle ring in a 3-ring setup should be...

Also play with derailleur height if you're running a seattube-clamped type. When you're running only 2 rings, you can optimize that a little more for some fudge-factor...

 

[indieboy]

Originally posted by MikeD
Jeez...29 to 44t?? Shimano fronts can only handle 12t of difference, by the book (or so I'm told). I have enough trouble with my 2-ring 36t/22t setup already!!

I went to an SRAM front and a Shimano trigger rear on both my trail and DH/FR bikes (both of which use 36/22). It helps a LOT, and you can get a set of SRAM shifters from Cambria for about $20 on closeout. The front shifter will work with any shimano mech., regardless of the rear shifter being SRAM (ESP) or Shimano specific.

It also forces me to buy 2 sets of ODI lockons at a time...! Gotta get one set shortie and one set regular, but then I have grips for 2 bikes with no waste in the end.

Actually, a 29/44 combo would be pretty good for me if I start racing DH a lot more...hmmm.... Big Bear spins out your 36t a bit quickly.

MD

yeah it's hard for a mtn front derailuer to push that jump between the two. the xtr doesn't have a hard time w/ it as much as like an xt or lx. but that's why a lot of ppl and mostly pros' will run a road front derailuer if they are pushing those types of gears. however most pros are pushing 32/44's, just a regular compact drive set up.