Is SRAM feeding me BULL!

[DKEG]

I recently, purchaced SRAM's new X-GEN front derailuer, I installed it and found that it was rubbing in the middle chain ring and the smallest cog's (8 & 9). When I set so that it would not rub in the smallest cogs it would rub in the largest cogs and visa versa. The other chain rings work O.K. I did have some problems with the largest but worked that out. I took it to a local bike shop. They found the same thing. SRAM sent me a new derailluer I installed it and the same thing happen's. I called SRAM about it, they said SRAM & Shimano derailluer's will rub in the middle chain ring and the smallest cogs. My old derailluer did not rub. Is SRAM feeding me bull? Does anybody esle's derailuer rub in these cog's?

[Dirt]

Hey David.

When you're talking about rubbing, you mean that the chain rubs against the side of the front derailleur?

One of the benefits of SRAM's older shifters is that they allow you to trim the front derailleur to eliminate rubbing. That is one of the reasons why I always liked SRAM better than "The Evil Empire". The grip shifters (which are still my favorites) allow you to micro adjust up and down to eliminate rubbing. Shimano just gives you one placement for the small, one for the middle and one for the big ring. My setups always had plenty of rub, regardless of how I adjusted them.

I don't know if the new shifters that you've got have that ability to trim the front derailleur. Since that was one of the major selling points of the old systsm, I'd be a little upset if the new ones tossed that out.

I hope that helps a little.

Please accept my sincere apology for not being rude or sarcastic in this e-mail (well I guess you can scratch sarcastic off that list now). ;)

Peter

[DaveG]

Ever since going to 9-speed I haven't been able to get the front der. rub free w/ shimano rapid-fire. I just recently switched to grip shift which allows you to fine tune the front der.

I think some bike/chainline combinations allow rub free operation, but none of mine do.

Dave

[markie@unformat]

I think some bike/chainline combinations allow rub free operation, but none of mine do.

Dave
All shimano here.

I have one bike that is rub free and shifts fine, another that needs some rub to be able to shift to the grannny. But it is still hit and miss with rub. Which is part of the reason I dont use the granny ring anymore......

[bikerRob]

I recently, purchaced SRAM's new X-GEN front derailuer, I installed it and found that it was rubbing in the middle chain ring and the smallest cog's (8 & 9). When I set so that it would not rub in the smallest cogs it would rub in the largest cogs and visa versa.... I called SRAM about it, they said SRAM & Shimano derailluer's will rub in the middle chain ring and the smallest cogs. My old derailluer did not rub. Is SRAM feeding me bull? Does anybody esle's derailuer rub in these cog's?

2/08/05 >> (My set-up...96' XTR/XT combo with Rapid/F shifters..8 speed) My thoughts on this...I ran my gears though a test and yes I have some rub too but only on my last (smallest) cog. Of course that's only because I tweaked my front deraillier more toward my granny ring so I'd have faster shifts and no rub when I shifted to my lowest (largest cog) gear. I probably never noticed this before because I've never had an occasion to use the gear combo you suggested...(* middle ring/last cog ) I usually double shift way before I'd need any gear higher than my 6th.

[CRAIG2]

I have that same problem as well, primarily with my road bike, and that has the Shimano STI shifters. Rubbing is slightly noticeable on the second to smallest, and really a nuisance on the smallest cog. Which really sucks, because that 39x13 is a gear I really like. So, my solution, similar to those below, is just to shift chainrings. The 53x17 and 53x15 aren't bad cruising gears either. Not sure what kind of front derailleur I have on the road bike - think it's a much older Deore topshift model that I picked up for like $15 second hand heading home when I was on a budget, and my RSX derailleur went.

Of course, as with Peter, I miss the old Shimano thumbshifters with the SIS/Friction shifting. Had thos on my old Miyata. Speaking of which, if anyone would like them, I'd be happy to sell them.

Craig

[drevil]

Rubbing is slightly noticeable on the second to smallest, and really a nuisance on the smallest cog. Which really sucks, because that 39x13 is a gear I really like. So, my solution, similar to those below, is just to shift chainrings.
Craig

Sounds like cross-chaining (http://www.bikeforums.net/archive/index.php/t-57259) to me. You had the right idea by shifting, but here's a calculator (http://www.sheldonbrown.com/gears/) to see any redundancies in your gear combos.

[DKEG]

Sounds like cross-chaining (http://www.bikeforums.net/archive/index.php/t-57259) to me. You had the right idea by shifting, but here's a calculator (http://www.sheldonbrown.com/gears/) to see any redundancies in your gear combos.

It may be cross-chaining, and I never remember using that gear combo. But I have set up many XT & LX derailluers and never have had this problem in the middle chain ring. I have checked the chain line of my crank and it is approx. 49mm which is well within SRAM's specs. I am a little anal when it comes to my gear. The smallest gear I can forgive but not the second and third smallest. I guess I could get rid of all but one of my gears.

[Dirt]

It may be cross-chaining, and I never remember using that gear combo. But I have set up many XT & LX derailluers and never have had this problem in the middle chain ring. I have checked the chain line of my crank and it is approx. 49mm which is well within SRAM's specs. I am a little anal when it comes to my gear. The smallest gear I can forgive but not the second and third smallest. I guess I could get rid of all but one of my gears.

So what you're saying is that you're in your small ring up front and the front derailleur rubs when you're in your smallest 2 or 3 cogs in back?

I guess I've never had that problem because I've never had any use for those gears. I don't use the charts that Ricky linked to, though I imagine they're good tools. I just go by feel. By the time I'm that far down in the cogset, I figure I need to be on the next ring up. I even do that with the middle ring too.

I suppose it's because I started racing back when 5 speed clusters were the standard and a freehub was something you got when Santa brought you bike parts for Christmas.

Maybe I'm delusional (insert joke about questioning my sanity here (http://glazeddoughnut.us/sanity/index.php)) but I always feel the drivetrain is inefficient when I'm cross geared like that. I feel it in the pedals, I look down and I say to myself, "No wonder! I'm crossing over most of the cluster!".

You'll find your chains last a lot longer by not crossing over that much.

Okay, I'm shutting up now. :)

Have a nice day.

Peter

[velvetmidget]

you just slightly adjust your left shifter if its a grip shift. If its the the "rapid" push type shifters i would adjust your derail to slightly rub in the 1-3 gears in the rear instead of 7-9. That helps keep your chain from throwing down to the small front chainring during rocky sections. Its a very easy adjustment for a mechanic they just need to know what you want done.

[DKEG]

So what you're saying is that you're in your small ring up front and the front derailleur rubs when you're in your smallest 2 or 3 cogs in back?

Have a nice day.

Peter

Pete, It is in the middle chain ring and 7,8,9 cog. I am in the middle 95% of the time. And though I don't use those gears. I want them not to rub if I ever did. I'm anal Like dat. (Hey! a new hip hop song title) Maybe SRAM's derailluer cage is not wide as Shimano's. I don't know? David

[bikerRob]

Pete, It is in the middle chain ring and 7,8,9 cog. I am in the middle 95% of the time . And though I don't use those gears. I want them not to rub if I ever did. I'm anal Like dat. (Hey! a new hip hop song title) Maybe SRAM's derailluer cage is not wide as Shimano's. I don't know? David

2/09/05 >> Not many people stay in the middle ring 95% of the time... :eek: ...Wow!..I'd love to watch you climb a big hill... ;) ...but seriously, I'd suggest checking the front deraillier set(stop) screws, particularly the one for the outer stop. Try setting it as far out as you can get it. Also bring the inner throw (stop) in as much as possible. This might center the setting for the middle ring a little more toward the outer gears. If this doesn't work you might have a chain line problem. Perhaps the bottom bracket is off set slightly to one side (?) If both crank arms are equal distance to the chain stays then that wouldn't be the problem.( 1-2 mm difference would be normal but an adjustment might help if all else fails.) Rob

[Dirt]

Pete, It is in the middle chain ring and 7,8,9 cog. I am in the middle 95% of the time. And though I don't use those gears. I want them not to rub if I ever did. I'm anal Like dat. (Hey! a new hip hop song title) Maybe SRAM's derailluer cage is not wide as Shimano's. I don't know? David

It may be the case that it is narrower. It is a tough choice in derailleur design. A narrow derailleur shifts better and faster... especially with ramped rings. The wider ones don't rub as much though.

I used to like the old campy front derailleurs because they were fairly wide and had no contours at all. I'd clamp them and bend the heck out of the cage so that it would shift faster. That was before anyone invented ramped chainrings. There's something kind-of fun about mangling a brand new campi derailleur to make it shift right. When I got done, it worked great. It didn't look so hot though.

Peter

[CRAIG2]

Hmmm... this certainly makes a great argument for converting to a single speed, doesn't it?

Alas, as far as my road bike goes, one day I vow to have a matching groupo on it. Except for the hubs. I got to good a deal on the wheels to let them go, and I've had my R500 since my messenger days, so it's grown on me...

Craig