[MCF]

A question to SRAM RED owners.....with the SRAM RED crankset, front dr, rear dr, and a SRAM RED 11-23 cassette, how much front dr rubbing are you getting if you are in little ring in the front and smallest cog in the back??

I already KNOW you are not supposed to do this, but I have read articles that say that "SRAM RED group allows you to cross chain without getting a noise violation ticket".....this tells me you should be able to go from small to small without rubbing, OR are they referring to big to big (big ring in front and big ring in back)?

I am having a bike built up with SRAM RED and the shop seems to be having trouble accomplishing this task - no rubbing with cross chain. So two questions....

With little/little, how much front dr rub are you getting? Barely any, a normal amount that you can ride and hear it but not too worried, or "OMG, I need to get out of my small cog quick!!!"

Same question with big/big cross chain.

I would really really appreciate anyones input. If you don't have SRAM RED, I don't need to hear, "You should never cross chain" as that doesn't help. I am just trying to get a baseline so when I test ride tomorrow I know everything is set up correctly.

 

[JacksonDodge]

A question to SRAM RED owners.....with the SRAM RED crankset, front dr, rear dr, and a SRAM RED 11-23 cassette, how much front dr rubbing are you getting if you are in little ring in the front and smallest cog in the back??

I already KNOW you are not supposed to do this, but I have read articles that say that "SRAM RED group allows you to cross chain without getting a noise violation ticket".....this tells me you should be able to go from small to small without rubbing, OR are they referring to big to big (big ring in front and big ring in back)?

I am having a bike built up with SRAM RED and the shop seems to be having trouble accomplishing this task - no rubbing with cross chain. So two questions....

With little/little, how much front dr rub are you getting? Barely any, a normal amount that you can ride and hear it but not too worried, or "OMG, I need to get out of my small cog quick!!!"

Same question with big/big cross chain.

I would really really appreciate anyones input. If you don't have SRAM RED, I don't need to hear, "You should never cross chain" as that doesn't help. I am just trying to get a baseline so when I test ride tomorrow I know everything is set up correctly.

Cross chaining means big ring and big cog. Doesn't apply to small/small.

I've done a dozen or so installs of Red(not including my own bike) and I've always told customers that an audible rub while in the small cog/small ring is totally normal and not indicative that something is adjusted incorrectly.

 

[MCF]

Thanks...so can you accomplish big/big with NO rub or will there still be a little rub in big big?? Thanks!!!!

 

[JacksonDodge]

Thanks...so can you accomplish big/big with NO rub or will there still be a little rub in big big?? Thanks!!!!

There's always a little bit of rub.

 

[MCF]

Thanks..I feel better. I told the shop to shoot for big big with as little rub as possible and then we can tweak to get 'acceptable' rub in small small.

 

[roadboy]

you should never under any circumstances ever be in the small small combo, this gear is replicated elsewhere, now the only time I do big big is on short hills where I dont want to drop out of the big ring, there is always a tiny bit of rub but this gear rarely gets used. I do use the big ring and second cog from the top more often, as a way to not drop into the little ring if I know I can get my speed back up in a short distance.

 

[Hooben]

I was having some issues with chain rub on the small small (climbing) I managed to tweak it so there is no noise whatsoever in the big big and small small. There will always be some chain rub when you cross chain it from the big ring to the 11. The best answer is to not ride this combination.

 

[orlin03]

I'm running the red crank and red front dr on a shimano drivetrain (yeah not exactly what you're asking), and had lots of rub in the small/small at first; I was able to adjust it out almost completely. It's now enough that I know I should have shifted to the big ring, but if I'm heading for the next hill in a few seconds, I can leave it there without sounding like an idiot.
One other thing: I had a recurring problem with the bolt that holds the derailleur to the clamp backing out just enough to mess up my adjustments and make for a noisy sloppy ride; I had to locktite it to keep it from happening.

 

[FatTireFred]

Cross chaining means big ring and big cog. Doesn't apply to small/small.

nope, cross-chaining is both the big-big and small-small... the two opposite extremes that you never need because they are duplicate gears. chain rub is gonna be influenced by cs length, shorter means greater chance for cross-chain rub because the chain is at a greater angle

 

[C-40]

trim...

There's supposed to be a left trim position on SRAM Red, to eliminate any rub in the big ring and larger cogs, but perhaps not the largest. Both the big/big and little/little combos are not wise to use on any drivetrain.

As mentioned, chainstay length makes a difference. A compact crank in the little/little combo will almost always rub the big ring. The big ring may even try to pick the chain up!

Isn't Campy grand? There's all the clicks you need to put the FD wherever you want it. Only four are required to cover the full range of travel.

 

[Andrea138]

I get a lot of noise when I cross small/small, but like everyone else said, you should avoid it if you can. With large/large, you can use the "trim" where you click once & the FD moves to the inside just slightly so you can avoid chain rub. If you want to go back, just give the left shifter a sweep & it goes back to normal big ring position.

 

[JacksonDodge]

nope, cross-chaining is both the big-big and small-small... the two opposite extremes that you never need because they are duplicate gears. chain rub is gonna be influenced by cs length, shorter means greater chance for cross-chain rub because the chain is at a greater angle

It's technically not "cross chaining" when you're in small small. You're not crossing the chain over any gap like you are when you're running a big/big combo.

I've tried to eliminate it from my vocabulary as it makes no sense whatsoever. All it does is confuse people.

Just sayin....

 

[Kerry Irons]

Redefining?

It's technically not "cross chaining" when you're in small small. You're not crossing the chain over any gap like you are when you're running a big/big combo.

It's great that you have single handedly taken on this issue and are setting the rest of the cycling world straight. How wrong everyone else is to define cross-chaining as when the chain makes a sharp angle, "crossing" from one chainring to the opposite cassette cog. Thanks for sorting this out

 

[JacksonDodge]

It's great that you have single handedly taken on this issue and are setting the rest of the cycling world straight. How wrong everyone else is to define cross-chaining as when the chain makes a sharp angle, "crossing" from one chainring to the opposite cassette cog. Thanks for sorting this out

Stop being so pompous.

You know exactly what I mean. The whole point is that the chain doesn't make such a sharp angle when you're running it in the small cog and small ring. At least not as sharp as the large cog/large ring.

It's a misnomer that drives me crazy.

It's far easier for me to explain that the small/small can be replicated elsewhere and save the cross chaining for the big/big.

But once again...what the hell do I know about bicycles?

I just work on them for a living.

<shrug>

 

[Kerry Irons]

Simple trig

The whole point is that the chain doesn't make such a sharp angle when you're running it in the small cog and small ring. At least not as sharp as the large cog/large ring.

Actually, if you have a correct chain line, the center of the chain rings is lined up with the center of the cassette, so the angle of the chain in the small-small combination is the same as the angle in the large-large combination.

 

[kevvwill]

Big/big combo, with zero rub. This is SRAM Red, 11-23 cassette, Cannondale SuperSix with the Si/Sl compact crank.

 

[eugkim]

Actually, if you have a correct chain line, the center of the chain rings is lined up with the center of the cassette, so the angle of the chain in the small-small combination is the same as the angle in the large-large combination.

I don't really have an interest in getting in the middle of a flame war, but the small-small combo will have less of an angle than the big-big because the effective distance between the rings (free chain) is less in the latter case. The angle measurements will be the same if taken from the center of rotation for the crank and the cassette. However, in the large-large combo, the chain is held in the ring/cassette teeth further out from the center of rotation. This makes the angle more acute. Wish I could draw a diagram to illustrate.

 

[RocketDog]

More trig... How long are your chainstays? It makes a difference.

 

[RocketDog]

I don't really have an interest in getting in the middle of a flame war, but the small-small combo will have less of an angle than the big-big because the effective distance between the rings (free chain) is less in the latter case. The angle measurements will be the same if taken from the center of rotation for the crank and the cassette. However, in the large-large combo, the chain is held in the ring/cassette teeth further out from the center of rotation. This makes the angle more acute. Wish I could draw a diagram to illustrate.

The FD moves both in the up/down axis as well as the in/out axis when shifting. There's the rub. Let's keep the Z axis out of this, yo.

 

[spyro]

I don't really have an interest in getting in the middle of a flame war, but the small-small combo will have less of an angle than the big-big because the effective distance between the rings (free chain) is less in the latter case. The angle measurements will be the same if taken from the center of rotation for the crank and the cassette. However, in the large-large combo, the chain is held in the ring/cassette teeth further out from the center of rotation. This makes the angle more acute. Wish I could draw a diagram to illustrate.

seems to me that the place we should be measuring from is where the chain disengages from the teeth of the chain ring or cassette... pretty much right over the center of rotation.... so the angles should be almost the same...

... I cheated and had to look at my bike