Roasted

I have an 08 Diamondback Response Sport. All stock for now except BB7's on the brakes. The rear derailleur has been acting up and I'm not too entirely sure what I should do at this point.

I've googled how to adjust rear derailleurs and also tried my best to use logic when watching the gears and chain line up, and to the best of my ability the shifter is calibrated the way it should be.

However, under heavy load when I'm running on the smallest gear it'll skip, which obviously makes me feel a little uneasy when trying to torque up a hill cause I don't want to cause any damage to the hardware here.

Do you guys have any tips for me to get this thing working the way it should? Or should I consider a new rear derailleur?

mzeffex 

Does the chain "skip" or "slip"? If it slips, IE, moving down to a lower gear when unwanted or does it skip, you try to move from 1st to 2nd gear and instead it goes to 3rd? Finally, when you are pedalling agressively does the pedal kind of lunge forward and make a clunk?

If it either slips or does the final description i gave you, it could be the cassette not the derailleur

operator

If it's skipping over the cogs, and not between gears, your drivetrain is probably worn out. You also need to do 2 things in addition to the park tool rear derailleru adjustment

1) Check hanger alignment
2) use new cable + housing

Roasted

Honestly, it feels like it's skipping between gears, as if the derailleur isn't sitting dead on the gear but kind of in between two gears. But it's strange cause the second it happens, I stop, flip the bike over, and I can see it's dead on. It's very confusing.

The cable and housing I didn't mess with or replace, but I unbolted the cable from the derailleur and it can pass freely through the housing. I know it's not the same as replacing it, but at least I can feel that the cable passes without any restriction.

Panthers007

Derailleur hanger adjustment. New cables.

deweyhtucker

A cable may feel free, but put a load on it. The spring force of the RD is a lot. Just pull on the cable with your hand to shift, and you will see how much force. A seemly free cable with out load is different when under load. Do what Panthers007 said.

Roasted

Hey guys - wanted to follow up here so maybe somebody can dig this thread up in the future and learn from it. I took it to the bike shop and the mechanic there went through a very thorough check with it. I have a 2 year warranty I paid extra for so it covers the cost of any parts that need replaced in the 2 year time span. The cassette at first glance didn't appear to be problematic, so we looked at some other things. We disconnected the rear derailleur, but kept the chain on the smallest gear. It still jumped... so we knew it wasn't the cable or anything else.

Then we tried a whole different wheel, thinking maybe the 1 way bearings in the rear hub were bad. Nope. Same deal. So then we tried a different chain, since mine wasn't looking too good anyway. Nope. Same deal. So then we ended up trying the cassette.... presto! I have no idea what was bad about the old cassette, because visually they did look the same and didn't appear to have any differences. So when I looked at them I thought for sure it wouldn't fix it. But with the new cassette everything is solid, and the ride feels MUCH different. Just goes to show you, visual comparisons aren't worthy... put the damn part on and ride it to see how it feels!

Anyway, case closed. I'm a happy camper now with a fixed up bike.

neil0502

Glad to hear

Personally, I'm thankful that you closed the loop.

I agree: if/when somebody searches the forum, the more they can find, the better.

tennisplyr3

Thanks for posting your follow up. It will be useful in the future.

Roasted

OKAY SO... I just took the bike out for a ride. I had only ridden it around town once or twice since I got it repaired. Work's been kicked in high gear so I haven't had much free time to ride.

Well, it skipped. Several times. Under high torque. Just like before.

-I know it's not the derailleur, because I disconnected it and it still skipped.
-I know it's not the derailleur cable, because I also disconnected this and it still skipped.
-I know it's not the cable housing, because with the cable disconnected it also skipped.

So, with the above being said, if I place the chain on the smallest gear and disconnect everything else, I in essence make it a "single speed", taking the cable/cable housing/derailleur out of the equation.

So what am I left with?

Chain - Brand New.
Cassette - Brand New.
Rear Wheel - Brand New.

.......What else? What else could this possibly be? I was so excited the first time I took it home from the shop. I mean I literally went up and down the street 400 times doing a stop-and-go test on the smallest gear throwing as much leg power as I could at it, since it only seems to happen under high torque. I just have no idea what else to consider and what else to look at.

Panthers007

Did the mechanic at your LBS check the derailleur-hanger alignment? Many times the hanger will be bent - by simple things like dropping the bike on it drive-side, stuffing it in a backseat of a car, putting it on a bike-rack where someone accidentally bangs their bike into yours....etc. So that's what I'd look into first. The hanger is designed to bend relatively easily the frame won't be damaged by a side-impact. A bike shop will have (one hopes) a tool to check this - and fix it on the spot. The whole job takes maybe 10 minutes - if the mechanic is lazy.

So your mantra should be - derailleur hanger alignment.

Roasted

I do remember he had some long gauge tool that he sized up and checked something in the back. I remember him saying he didn't think it would fix it, but he'd try another derailleur anyway... so he did... and it did the same thing even with a new derailleur...

DMF 

How badly does it skip? It might be the front gears...

Does it matter what front ring you're in?

I assume you're running the correct lock ring if your small cog is 11T?

Anyone check rear triangle alignment?

Try replacing the derailleur; the cage might be slightly bent.

And check the hanger alignment again. Twice.

Roasted

Triangle alignment wasn't checked in my presence, but the derailleur alignment I'm pretty sure was. Secondly, we tried 2 derailleurs and both did the same thing.

I'm not too sure about the 11T thing with the small cog. But I can tell you it has been duplicated on other gears as well. It's just more obvious on the smallest gear since that one I can apply more torque to before speeding up to the point that I wouldn't be able to duplicate the skipping.

I've been staring at the front set of gears by the bottom bracket as I duplicated this, and I visually didn't see anything that was obvious regarding this, and when I had my eyes focused on it and it skipped, at that point I knew just by the sound/feel that it was indeed coming from the rear.

The LBS told me that if this happens again they'll just swap out the bike, which is part of the 2 year extended warranty I purchased for extra $$. I may take my BB7's off (only aftermarket part) and put the Hayes back on and take them up on that. I just didn't see any other bikes that really stood out to me besides the one I got... so it'd be a real crapper if I had to get another.

Panthers007

There IS a solution to the problem. I would say, but not sure you could do it out-of-pocket, you should look into another bike-mechanic. Sounds like your current one threw in the proverbial towel - especially if you're being told they'll swap out the bike. I'm still very curious if this guy actually used the derailleur-alignment gauge. Maybe he didn't know how to and was trying to save face? Anywho - if someone brought that bike to me, I wouldn't toss in the towel until I'd looked into every possible cause/remedy. It would be a challenge to me. I'd sleep on it, too (not the bike - I love bikes - just not in that way), and try again until I found the solution.

You have a frame. You have a rear-derailleur. You have a derailleur-hanger. You have a cassette. You have chainrings up front. You have a chain-line coupling this altogether. Now the only thing missing is right under your nose. What is causing this? I'd find it.

EDIT - have you checked the chain for any abnormalities? Tight link perhaps?

Roasted

Perhaps, but this mechanic seems like a very nice guy and very knowledgeable. I paid extra for an extended warranty, and part of the deal with their extended warranty is if there is a problem with the bike that keeps reoccuring, they'd replace the bike of equal quality so I wouldn't be at the shop 100 times a week, just because it'd become a nusance from my point of view.

I've talked to this mechanic for a while, and we've gotten into general conversation. This bike shop is 35 miles away. It's not "convenient" by any stretch for me to keep coming back with this problem. It's because of this he threw that option out there, but on top of that as I said it's also part of the extended warranty to begin with. Every time I go in there, even if he has other bikes on the shelf to repair, he does mine on the spot cause he knows I go way out of my way to make it there. I also do know that he used to compete with racing. I'm not a genius with mountain bikes. I'm a computer technician myself. I know when I go to Best Buy when sales rep's ramble about certain things, you can kind of sift out who's talking BS and who knows their stuff. I get that vibe with this mechanic, to be completely honest. I'm not trying to go out of my way to say naw naw this guy's great etc, but I really think he's knowledgeable in this department and despite them being a good distance away, I'd rather go there than some of the other LBS's closer to home. That's why I bought my bike where I did.

I know he checked the frame for alignment and it checked out fine. I don't have a tool for measuring the alignment of the rear derailleur hanger, but I just had this problem on my brother's mountain bike and it was obvious to see by looking at the rear of the bike. From my naked eye, using no tool, my rear derailleur hanger seems to have the derailleur lined up perfectly with each gear that I shift into. I know it's not the same as an accurate tool, but a visual checkup on it suggests it just might be okay as well. I honestly believe that it was checked at the shop too. I remember him mentioning it when I was there. I was on my cell half the time I was there due to work so I can't remember if I saw him actually do it or not. Also keep in mind of several things...

I have a brand new cassette.
I have a brand new chain.
I have a brain new rear derailleur.
I have a brand new rear wheel.

I know the front set of gears is not the problem. As I mentioned, I've had my eyes fixed on the front set of gears when I torque down and I am certain that the issue was at the rear of the bike, based on the direction of sound and the way the chain wobbled towards the back of the bike.

I just honestly don't know what else it could be. As a computer technician, you need to swap out parts and look for little breaks on the circuit board to figure out which part might be causing the problem. I know this is the same mentality you need to have with bike parts too. Ironically enough, at work I have a computer I'm working on where I can't get the USB ports to respond, as a result it doesn't boot because of no keyboard detected. I have replaced every single part (no exaggeration). It still does it. This bike is honestly reacting the same way this damn computer does on my desk at work.

The bike shop opens shortly, so I plan to call them and see what else he thinks.

EDIT - yes, after reading your question about the chain, I did check the chain. I spent 20 minutes and went through each link and made sure each link could easily bend in both directions. I honestly did not see anything whatsoever with the chain that would suggest this was the issue.

andychrist

Duh-uh.

Maybe you should try a more appropriate gear for what you are attempting?

Just a thought.

Trakhak

Yes. Smallest cog wears extremely quickly. As Sheldon Brown said:

Try to avoid the gears that make the chain cross over at an extreme angle. These "criss-cross" gears are bad for the chain and sprockets. Especially bad is to combine the inside (small) front sprocket with the outside (small) rear sprocket. This noisy, inefficient gear causes the chain [and small rear sprocket] to wear out prematurely.

https://www.sheldonbrown.com/gears.html

Roasted

What gear are you in when you're going down a hill? Do you stay in the largest gear? Somewhere in the middle? Do you ever utilize the smaller gears on the cassette? This problem happens when there is a decent amount of load on the smallest gear. And this includes when I'm going down a hill trying to speed up, just when that smallest gear feels absolutely perfect for the speed I'm going. My point by saying it only happens under load was to understand that if I'm sitting down on the bike, the power I can push through my legs to the pedals isn't enough to make it skip. If I stand up, then that amount of torque I can apply to the rear seems to set the stage for a skip. Do you ever stand up when you're biking? If you do, then that alone nullifies what you just suggested to me.

I have 2 bikes. This bike does it. The other bike, an older, much cheaper bike I CANNOT get to duplicate these results no matter what I do. My brother's Schwinn that came straight from Target can't even duplicate this same issue that keeps popping up with the Diamondback. Also, keep in mind, I've gotten this to do it on other gears too. It just seems to happen all the damn time on the smallest and 2nd smallest gears.

Now, I'd appreciate it if we can keep on topic with constructive ideas on what else I could do to get this thing fixed, instead of just "avoiding that gear."

Roasted

I am well aware of this. And actually, I have avoided it ever since I've gotten into biking. The chain is not being "crossed" on my bike when I get these skipping results.

andychrist

If you are relying on the smallest cog when climbing a steep hill then you are inviting trouble. Why do you think your cassette has other gears on it? The smallest cog is for low load, you normally shift to the larger ones when you have to apply a greater force. If you don't want to take advantage of your gear range, why not just switch to a fixie and be done with it?

Different bikes will have different components. Newer bikes use systems such as hyperglide to facilitate shifting and the cogs on these cassettes may not be as deep as on an older bike. I can get either of my DFs to skip if I stand on the pedals in a gear that is too high for the grade I am climbing. On the two smallest cogs, the chain is only engaging a few teeth so it might easily skip under the situation you describe.

Hope you get your computer fixed.

Roasted

I should take a picture of the hill I'm speaking about. It's the hill on my street. It's just enough of a slope that a car in neutral would coast down the street, but nothing mt. everest style.

I hate to keep firing this out, but my old bike doesn't skip even if I directly try to abuse the rear cogs in any way shape or form I possibly can, and this bike is significantly cheaper in quality and components than what my current bike is. There is clearly something wrong with it. And if this is "normal" practice for this bike in particular, I won't be getting another. To stand up to get better leverage with pedaling harder and endure 4-5 skips of the gear before I make it 150 yards up the street to the stop sign is just ridiculous. Even the guy at the bike shop said it's not right at all.

andychrist

You said you replaced the cassette. Did you replace it with the exact same model, or have you tried a different make? Because you are right, if you are just mashing up a mild incline, your drive chain should not skip. Also, have you adjusted the B tension screw? (This controls the distance between the jockey pulley and the cassette.)

Dollars to donuts though, if you replaced your DB with another, you'd have the same problem. So maybe yeah, try replacing that derailleur, but with a higher quality one, at least say a Deore LX or a SRAM 7, ask your LBS what would be a compatible upgrade.

Roasted

Yes. It was replaced with an identical cassette. I know this because the bike shop did not have many parts on hand at the time, so they disassembled the same model bike and piece by piece tried out new parts on the bike until something worked.

They put a rear derailleur on it and it didn't help, so then they put the old one on. Then they tried a new chain after realizing that mine seemed to be a bit worn. It still skipped then. Then he swapped the cassettes. Immediately I felt a difference. It seemed stiffer, yet smoother, and glided a little better. The shifting was more responsive. There was no doubt my old cassette had something wrong with it. So after that, we called it a day and that was it. Oh, and I forgot to mention. To rule out my rear hub's 1 way bearings being an issue, they put a brand new wheel on the rear too. So the order went:

New rear wheel - didn't help.
Tried another derailleur of same make - didn't help.
New chain - didn't help.
New cassette - felt noticably different.

Then afterwards, I came home and didn't ride much for about 2 weeks. I got on it yesterday and it skipped for the first time. Today I spent more time on it and it seems more and more it's skipping now.

Also, just to throw this out there... Before all of these parts were changed, the bike mechanic would get on my bike and real quick just rip up and down the showroom floor in the bike shop. On this flat ground within the store he got it to skip several times, even on the 2nd to smallest cog. After the cassette was put on, we couldn't duplicate the same results in the store, so we went outside where I rode it. I didn't seem to have the issue, so we called it a day.

But like I said, fast forward 2 weeks and very little riding and suddenly the issue is back. So now you can see I wasn't abusing the bike. Even a simple place like the showroom floor this issue occured. I do admit, it stopped after the cassette, but now it's back.

DMF 

I wonder if major flex at the BB could cause this?

Roasted, could they replace it with the same model?