Bicycle Mechanics - is the b screw adjustment very importtant?

on a sram x4 because the screw slips by the grove its supposed to rest against on my bike i can see where it wore a grove .so if i try to get the cogs closer to my rd pulley it wont work close i can get is like 14 mm

this is a pic of another rd not mine but the part i circled is worn so the screw just keeps going never resting on the part i have circled http://img4.imageshack.us/img4/5860/der117.jpg (http://imageshack.us/photo/my-images/4/der117.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)

I have flipped the screw over, then the Head is wide enough to hit the frame stop.

right now i hot glued a small pice of plastic between the screw and rest

IDK if it is, or even what all that meant, but I do know that spelling is important.

Either the glued on insert, or flipping the screw over will work.

But I'm curious, why is the screw turned down all the way? It's rare that the RD needs to be pushed down that far, and as you bring the screw back, it'll come in radially and get a better purchase on the stop.

Otherwise, ir the Jerry rigged fixes don't work for you, bring the frame to someone who can weld a small amount of filler behind the stop, which you'll file to shape afterward. This is an easy and permanent fix for the problem. (but as I said, first confirm that you do have a problem)

For a semi-permanent sort-of-fix, you might try building up the worn spot using some epoxy like JB Weld. Build a small form for it from some cardboard and then file it down to the appropriate level when it's fully cured.

For a semi-permanent sort-of-fix, you might try building up the worn spot using some epoxy like JB Weld. Build a small form for it from some cardboard and then file it down to the appropriate level when it's fully cured.

Be very careful filing epoxy - the dust from many of them is carcinogenic. This from the JB Weld Material Safety Data Sheet:

High concentrations of pigment-grade (powdered) and ultrafine titanium dioxide
(titanium oxide) dust have caused respiratory tract cancer in rats exposed by inhalation
and intratracheal instillation. Product is a non respirable form.

Note that the dust from product is respirable when you grind or file it.

Do it outside, with a dust mask. Wash down the work afterwards. Or - perhaps don't do it at all.

Just so's you know anyhow.

Is this on your new bike??

Since the Felt Nine Flow comes with a SRAM X4 I'm thinking this your new bike. If so it should be a warranty issue. Otherwise your frame has a replaceable derailleur hanger, which means you can remove the piece that the deralleur attaches to and replace it with a new one where the B tab has not been worn away. http://www.feltbicycles.com/USA/2013/Shop/Parts/Mountain/MTB-Cafe-X-City-Derailleur-Hanger.aspx

yeah it is my new bike .i forgot about the warranty

To answer the original question: yes I think it's important. My shimano XT rear derailer on a new bike had rather ponderous shifts until I adjusted this properly. Bringing the derailer 10-15mm closer than it was has made the shifts a lot more positive.

All this and you have a replaceable hanger which may be under warranty? Replace the hanger, either free or buy depending on circumstances. Then prevent a recurrence, by pulling the RD down off the stop when adjusting the screw. This will prevent wear and grooving on the hanger's stop tab.

The "b" screw is one of the most misunderstood adjustments on the bike. It is to be adjusted so that the jockey wheel (the upper one on the RD) misses the largest sprocket on the rear cluster by a specific measurement. On my Sram 7 the clearance is listed at 6mm when the jockey wheel is in alignment with the large sprocket. This clearance is best measured with the chain off. BTW that clearence is easily measured with a 6mm wrench.

Is SRAM different than Shimano?
Shouldn't the OP be BACKING out the screw to get the guide pulley closer?

Which cog & ring?
Shimano says the largest cog & smallest ring and then check against smallest cog to make sure there isn't interference.

Is SRAM different than Shimano?
Shouldn't the OP be BACKING out the screw to get the guide pulley closer?


No,
Yes.

The "b" screw is one of the most misunderstood adjustments on the bike. It is to be adjusted so that the jockey wheel (the upper one on the RD) misses the largest sprocket on the rear cluster by a specific measurement. .

+1

yeah it wont slip in to the groove to i let the screw out when i screw the screw in it must change the angle because it dont go in grove but im like1/2 inch of clearance then

yeah it wont slip in to the groove to i let the screw out when i screw the screw in it must change the angle because it dont go in grove but im like1/2 inch of clearance then

Really no idea what you just said there?

Have you tried backing out the screw and actually running through a few gear changes to let things "settle out"?
The position/distance will probably change.

yeah it wont slip in to the groove to i let the screw out when i screw the screw in it must change the angle because it dont go in grove but im like1/2 inch of clearance then

OK, that's pretty much completely unparsable...

i stink at making my self clear. but ty for all the help everyone think ill just order a new hanger..are all hangers universal? or do i need a certain type? for my bike?

hangars are bicycle brand and model line specific. there's probably 35 or 40 different ones.

there's a couple websites that sell just about any hanger made.
http://www.derailleurhanger.com/
http://wheelsmfg.com/products/derailleur-hangers.html

etc etc.

wow there sure is a lot of them glad i asked.

also, old school steel frames. especially the better ones, the hangar was part of the dropout casting, and not replacable. the one in your picture is of this sort. but those were forged steel and tended to not fail.

To answer the original question: yes I think it's important. My shimano XT rear derailer on a new bike had rather ponderous shifts until I adjusted this properly. Bringing the derailer 10-15mm closer than it was has made the shifts a lot more positive.

+1. I usually turn it out untill the RD hangs up on the low gear cog then turn it in a touch so it doesnt hang up. Most mechanics have no clue as to properly adjusting the B screw.

We just did a repair at the shop with this issue. A GT ATB with a Sram. The end of the B screw had gauged the hanger tab so the screw would slip past and the der would hit the chainstay and only go up the cassette a few cogs before the guide pulley hit the cogs. A replacement hanget was the fix.

But a note aboput the Sram B screw. It has a short beginnng section of no threads so the end face of the screw is smaller in diameter then the Shimano screws (which are fully threaded). This allows the screw to better gauge out the hanger tab. Andy.

....

But a note aboput the Sram B screw. It has a short beginnng section of no threads so the end face of the screw is smaller in diameter then the Shimano screws (which are fully threaded). This allows the screw to better gauge out the hanger tab. Andy.

Gouge or gauge?

I assume you mean gouge, which is precisely why I strongly suggest pushing the RD down to pull the B screw off the stop when making the adjustment. The same practice should be use when adjusting the slack cable limit screw. Turning these screws while under load, wears away the contact points they are supposed to merely rest on.

i stink at making my self clear. but ty for all the help everyone think ill just order a new hanger..are all hangers universal? or do i need a certain type? for my bike?In my post #10 I included a link to the Felt bicycle site, here it is again (in blue) http://www.feltbicycles.com/USA/2013/Shop/Parts/Mountain/MTB-Cafe-X-City-Derailleur-Hanger.aspx If you click on the blue letters and numbers, it will take you to the Felt bicycle site and the derailleur hanger for your bike. You can then order the derailleur hanger there and they will mail it to you.

yeah it wont slip in to the groove to i let the screw out when i screw the screw in it must change the angle because it dont go in grove but im like1/2 inch of clearance thenLet me see if I can translate this for the OP. "The "b" screw will not slip into the groove, that by passes the "b" screw stop, if I loosen the screw. However, even when the "b" screw is in the groove, it appears to be doing something, because when I loosen it the "b" screw out of the groove, the clearance between the pulley and cog increases to about a 1/2 inch."

windhchaser, is this what you were trying to say?

Something is "fishy" here-
refer to posts 15 & 16