Portis

I just broke by 2nd front derailler cable in less than 2 months. Both times it happened while on a ride and while i was trying to tighten the cable to get the front derailler to travel farther outward towards the outermost chainring.

Why is this happening? Should i not be trying to tighten it? It certainly has ruined two perfectly good rides.

Also how hard is it to change the derailler cables? The park tools instructions looked pretty simple.

1. Do i just need to buy some cables and a set of cutters?
2. Are the cables pretty much universal?
3. Do they come with the "ball" already on the end?

I am tired of hauling this bike to the lbs every time i break a cable. It also looks like i might need to start carrying one with me. I've broken more cables than i have had flats on that particular bike!

Dusk

It the shop is fixing it for you I"m starting to wonder if you need a new shop.

Knowing where they cable is breaking would help.

Here is what could be wrong.

If it is near the start of end of a cable housing, you might have a bur on the housing. It needs to be finsihed (filing)

If it is an old bike I have seen rust in the middle of a housing cut the cable. You should see rust on the cable if that is happening

If it is at an place where the cable is not in a housing. Could be your bike rack is pinching it or something is resting against it when you store the bike.

Does it shift Ok most of the time? If not your HI LOW setting of your Front D is not set right you might just be pulling against it and no mater how hard you do it won't shift and something has to give.....so far two cables.

Without more info that is all that comes to mind to look for.

Cheers

Portis

It broke this time right at the clamp that holds it to the derailler. It is not in a housing. It seems like it broke in about the same place the last time. Both times it broke when i was trying to tighten the cable via the thumbscrew on the shifter. It seems to me that it just runs out of cable and if i tighten it, it breaks. I will include a pic later (dead camera batteries) but basically it will just show that the cable broke right at the clamp on the front derailler. The cable was maybe 2 months sold.

The front derailler was shifting fine but the chain was rubbing on the outside of the cage so i was trying to get the front cage to move outward, providing more clearance. This was happeining using the outermost chainring and some of the outermost cogs. It is a somewhat seperate issue but my LBS put a new bottom bracket on this bike awhile back and they stated that the only one they had was a little bit wider than the original but it seemed to work ok.

So it seems that i am having issues getting the derailler to push the chain outward enough to land on the outermost cog.

s

Dusk

Okay....I'm not getting soft warm feelings about your shop. Sounds like they put a BB for a triple crank in your bike and it should have been a double Do you have a double or triple? If have a double and you have a double front D and now have a triple BB you have two choices buy lost of cables or get the right BB back in the bike. The only reason to put a wider BB in a bike is if you are touring and can't wait for the right part. Even then you are going to replace the BB with the correct one ASAP.

I would only cut the shop some slack if you were yelling at them to just fix the F*@!#$*^ the first time. If so you bad!... other wise....Bad Shop...no repeat customers.

Ask yourself after breaking two cables….does it seem to work. If it wasn’t the shop manager or the owner that worked on your bike. Talk to them they will see the problem and want to get you the right BB. If it was…..the Shop manager the Owner should help. Other wise tell everyone that name of the shop and what happened. Vote with your feet! Don’t walk into the store again.

Portis

I know i have shop issues, not the least of which is that it is the only one in my city. I have a triple front chain ring on my mountain bike. I didn't like the fact that they put a wider BB in but i haven't made any noise yet. I guess my question is: Can you break a derailler cable by tightening the thumbscrew? While riding?

Dusk

Well from what you have told me Yes you can. it must take one heck of a turn to do it. Do you thumb wrestle professionally?

The same logic applie if the BB is a triple but still too wide for the Front D and you have. And they told you that it was too wide.

I would talk to them to see what you can get resolved. It would be very sad to not be able to trust your local shop and not fair to them to not give them a chance to take it right. But if they don't...what is worse going on an hour drive to a better shop a two hour walk back every few rides.

Talk to them and let us know what happens.

cheers

sydney

It's a good bet your hi limit screw is set too tight.Then you add more cable tension,throw in some force to try and make it shift and the cable brakes. The cable clamp bolt could also be too tight and partially cutting the cable. www.parktool.com has derailer adjustment n the repair section. A BB spindle a few mm longer shuld not create or add to the problem, if the derailer is adjusted correctly.

DocF

I agree with this diagnosis. I do all the adjustments/minor repairs on our bikes and on most the the neighborhood kids' bikes. A great investment is a good repair guide, a modest priced set of bike tools and an inexpensive repair stand. I've saved the cost of these items many times over.

Of course, I must admit that I enjoy fixing bicycles as much as I enjoy riding them.

Good luck,
Doc

seely

I see the problem as this--

-The limit screws are adjusted improperly which is why you are having shifting issues, its not cable tension (just my guess)

The reason I say this is because if you are having to make the cable so incredibly tight to make it shift properly, then the issue isn't cable tension. It shouldn't need to be set very high at all for a front der. anyways. Usually just "taught" is a good tension, not "tight".

-The cable clamp is too tight!

Now both of these hinge on the issue that a) you have the cable routed properly in the clamp, and b) you are using the correct bottom bracket/crank combination.

Feltup

Seely is exactly right. Some one is doing a poor job replacing your cable. I think you should do it yourself. It is very easy and cheap.

Michel Gagnon

Seems strange. I don't have STI nor never played with it, but I have never been able to tighten so much a derailleur cable via the adjusting screws, barrel adjusters, limit screws, etc. I could strip threads if I use enough force, but that's it.

So I won't go against what others have said, but I would look at other issues too. Namely:

- Is the shifter cable rubbing against a derailleur screw, a rough metal guide, etc. near the place where it breaks?

- Is there something rough in the part of the derailleur where the cable enters and is attached?

It looks to me that something rough is "filiing off" or wearing the cable prematurely. One trick you might do is use a fishing line or dental floss as a derailleur "cable" to see where the wear occurs. These types of wire would break apart fairly quickly if there is any kind of abrasion.


P.S. I had issues in the "good old times" (1970s) about breaking derailleur cables yearly, but it was always the rear derailleur and always near the lever, because of the bend.

roadfix

Your outer limit screw is not set out far enough and by turning out the barrel adjuster and forcing your shifter to push the deralleur out further against the limit screw is snapping/freying/breaking loose your cable. That's what I see in my cyrstal ball.

Portis

This sounds the most likely to me as well. I hadn't messed with the limit screws because everything seemed to be shifting fine. I just recently noticed the chain rubbing on the outer edge of the cage when in outer/outer combos.

I took the broken portion of the cable out of the clamp. It snapped cleanly, flush with the upper edge of the clamp. The clamp is just two pieces of metal and a screw. (wire sandwiches between them) I don't see anything that could be cutting it.

Astra

I agree with everyone who says it's the hi limit screw. It sound like you are over tensioning the cable in an effort to get the front derailleur to move out a fraction to stop the rubbing.

Because of the limit screw, the derailleur can't move out enough to stop rubbing no matter how hard you tension the cable. It's breaking where it is because that is where the cable is most fragile duee to being pinched down onto the derailleur by the retaining bolt. Again, if your LBS didn't spot this, shame on them...

Portis

Well, i took it to LBS yesterday and they were to busy to fix it. I will take it back today and let them put a new cable on it. Then when i get it home i will check derialler setup myself and adjust if necessary. Next i am going to buy some cables. Do i also need cable cutters? What else do i need for DIY cable replacement??

Raiyn

Cable cutters are helpful for cutting housing and getting a non "crushed flat fishtail" end on the cable. Cables, housing, proper allen wrench, and the cable cutter are about what you would need.

Portis

OK. The cable was replaced by LBS. They gave me a song and dance about the derailler being at a wierd angle, blah, blah, blah.

I have included a pic of the way the front derailler looks now. THey have the Low screw screwed all of the way in, as you can see. The picture details the chain on the outer chain ring and the outer cog. I guess they basically told me that it will probably break again because the cable is tight and the derailler is in a wierd position.

I know i am getting the run around and need to do some of my own homework and repairs. I am suspicious of the wider bottom bracket that they replaced. Does the pic tell anyone anything?

BTW, the white in the pic on the derailler is "lube." That they put on. Granted it was a younger kid but geeeeeeeeeeeesh.... (see pic below)

Portis

This is a closer picture but the chain was inward a bit on the rear cogs. Since they screwed the L screw all of the way in, they have set it so the the derailler will travel inward the least amount possible. Why did they do this?

Does this effect the amount it will travel outward?

gorn

I'd say shift (gently) to the two biggest gears (As in size, not hardness). Look at how the chain and the front derailer are. Is the chain hitting? If so try tightening the "high" screw until it lets you shift so it doesn't get in the way. Then check to see that biggest front and smallest rear still has clearance.

sydney

I'd say to go to the repair section at www.parktool.com and learn how to adjust a derailer by starting at the begnning. If the BB spindle is too long,you will likely be wasting your time as the derailer may not have enough reach. It may make it to the big ring,but could not be adjusted so as to not rub in normal operation.

roadfix

In the 30+ years of serious cycling, I've never had any cable snap on me.
Your LBS guy obviously has no idea what he's talking about. If they think it's going to snap again, why can't they correct it or offer you some sort of suggestion so you can correct it yourself?

Trek Rider

I'm gonna take a W.A.G. and say that if they put a BB in that is too long, It may have caused the front der to reach the outer limit of movement before it reaches the position where there is no rubbing in the big/little combo. By tightening the adjuster screw a little more and then shifting, you place even more force trying to get the der to move when it's already at the limit, which it can't and something has to give. In this case the cable.

You mentioned that they (the LBS) claim the der is at a wierd angle. That reinforces my suspicions that the BB is the wrong size. From the pics it looks to me that the der is at the limit of its travel.

How did it shift before they replaced the BB?

halfspeed

I think the reason your high adjustment has been out of whack is that the new, wider, bottom bracket moves the crank farther out from the frame. Since the derailleur is mounted to the frame, if the high limit isn't moved to compensate, the chain will rub. If you get the hi limit all the way out and the chain still rubs, your BB is too wide. The fact that the low limit is all the way in would also indicate that this is likely. Increasing the tension on the barrel adjusters will not help. The LBS either doesn't know or doesn't want to admit that they screwed up and installed an incorrect BB and is trying to tweak around it and hope you go away. I don't get the FD is at a weird angle excuse. Are they saying it is bent? If not, then why can't they adjust it?

To answer your questions about replacing cables:

1. Yes.
2. Yes, as long as you do not confuse brake and derailleur cable
3. Yes.

And I'd add that if your housing is getting old, it wouldn't be a bad idea to replace it at the same time.

roadfix

Ranger......do a quick visual check and see if the middle chainring falls right in line with the middle of your cassette. If you have an 8-sp cassette your middle chainring should be approx. in line between your 4th and 5th cog.

Portis

Fixer,

See attached pic of chainline with chain on middle chainring and 5th cog. It appears to be in line to me. As far as the front derailler adjustment goes, it is fine according to the instructions provided at parktool. It has minimal clearance on the inner combo as well as the outer combo. (inner chain ring and inner cog as well as outer chain ring and outer cog. ) The deal is that they had to set the inner travel of the L screw at it's minimum. IOW, they set it so when the chain is shifted to the innermost chainring, the derailler moves inward the least amount possible.

I have to assume that they did this because there must be a relationship between the L and the H screws. IOW, where you have L set must effect how far outward the derailler can travel. Is this correct? (maybe the relationship is only that if the L screw has to be set outward to hit the inner chain ring correctly than the H screw has to also be set outward) It looks like to me they had to have the L screw all of the way in to get the chain to line up with the inner ring because they put the wider spindle on it. It looks like there is still some adjustment that should allow it to go outward a bit more.

As far as the shop goes, they are good guys but there are problems. I don't get professional service from them and realize that i never likely will. I still like them and will have to give them some business on things i can't accomplish myself but i am now ready to start tackling my own minor repairs, like cable replacement, chain and cassette replacement etc.

They were honest with me and told me they put a wider BB in when i had the BB replaced. They told me that was the only one they had. Obviously they should have called me and let me make that decision but they just replaced it. I didn't make noise because they are the only shop in town and they have treated me well most of the time. They often put my bike ahead of others because they know i ride a lot. THey also have made repairs for free. In a perfect world, there would be multiple shops in my city. I think we are lucky to have one based on what they tell me. We live in a very conservative market where people think spending $300 on a bike is excessive. So I can sympathize with them to a degree.

I guess i feel like preserving my relationship with them is more important than getting everything done exactly right. If this were just another business transaction, like a car repair for example, i would make a lot of noise and complain. I have done it before and made a lot of people wish they had never met me.
However, this is different to me. I think it would somewhat ruin my cycling experience if i lose my friendship with my LBS guys.