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24

The first rule is make sure the rear derailleur is adjusted correctly before adjusting the front derailleur. There are three adjustments that you can do on the front derailleur: Clamp Position Low limit stop High limit stop Clamp Position Here you can adjust the height of the derailleur, normally this is recommended as a 2mm clearance between the ...


10

Yes, there is a difference between front chainrings for derailleur equipped bikes compared to bikes without a derailleur. Basically a derailleur suitable chainring "wants" to fall off. It's designed so that the chain is happy to climb onto the gear and also fall off the gear. There are various ramps for the chain to engage into. Non-derailleur chainrings ...


9

There are a number of reasons that the shifting on your rear derailleur is not working well: The derailleur hanger (the bit of the frame that the derailleur bolts onto) could be bent. To check this look at the angle that the derailleur cage is at. When viewed from behind, it should be vertical, when viewed from above, it should be parallel to the ...


7

It is absolutely possible to skid the back wheel, but you really need to be deliberate about it to do it. In this case, however, it sounds like you were applying back pressure to slow down and noticed something surprising, so it was not likely to be the tire skidding. It was probably the cog slightly loosening. If you're going to apply any back-pressure at ...


6

The difference probably arises because there is more tension being exerted on the chain when you are cycling as compared to the bike being up on a stand. The screws on the dérailleur (as you probably know) are for setting it to stop at the right place (ie not to come off either towards the wheel or off the small gear). Do you have shifters which move the ...


6

That sounds like the rear cogs are worn, the likely fix is a new chain and set of cogs for the rear (you have to replace them both at the same time otherwise the problem will persist, perversely even worse). I suspect the bike shop fixed/replaced the stuff that was obviously visibly knackered and hoped for the best. In truth I suspect they needed to do ...


5

I'd go with the following hypotheses, beyond that already proposed: Your derailer is a bit misadjusted, so the gear is already almost shifting down. When you pedal hard, your frame flexes, thus releasing some cable, and the gear shifts "automatically". This is specially true if you have a brazeon on front part of downtube, then the cable runs outside of ...


5

In order of least expensive to most expensive, you either have a misadjusted derailleur, a very worn out cassette, or a crack in your frame. If you're not noticing any problems shifting under normal circumstances, I'd odds are good that your cassette is worn out and your chain no longer meshes with the cogs correctly.


5

I would have started by noting which gear (front or rear) is slipping and adjusting the tension on the corresponding shifter/derailer to bring it closer to correct adjustment. A rule of thumb is, make the adjustment and if it gets worse then you are going the wrong way :-) If the shop changed your chain did they also change the cassette (rear gears). The ...


5

Learning some better shifting technique may solve this. It also could be that, despite your best efforts, the derailers are out of alignment. Two questions: Is the chain falling off on the front chainring or on the rear cogs? If so, is it happening on the inside or outside? (If it's happening in the rear and the chain is hitting the spokes, this can be ...


4

I'm surprised they do it on a stand. The flex of the frame while in use makes a significant difference in how it needs to be setup! I put my bikes on a trainer when doing the shifting calibration. That way I can jump on the bike and do test runs under load. Sometimes ends up being a bit clunky if you spin it by hand while not riding, but always works ...


4

I would bet for the chain having rusted, leaving some links "locked" and not turning free between each other. Also, if rust built over the sprocket's teeth surface, it can cause the chain to skip under pedal load, bacause the chain doesn't engage properly. I am telling you this because my damn lovely(#@%) cat pissed the cog cluster of one of my bikes, and ...


4

Assuming it's not been used it probably needs a touch of lube and some adjustment. If your friend only rode it for a month he probably didn't even get the bedding in service done on it. New cables on a bike normally bed in after a little while (time depends on use) and so things go out of line fairly quickly initially which is why bike shops normally do ...


4

There are some pitfalls beyond the correctly pointed worn teeth, mentioned by Colin Newell: Derailer hanger might be misaligned, which causes some gears to not properly engage; The "bent" derailer, which was straightened by the shop, might not be totally straight yet, even if it looks so (there is a parellellogram that needs to be perfectly aligned to work ...


3

There could be several possible reasons for this behaviour - Derailleur could be out of adjustment - can be fixed by barrel adjuster/adjusting the tautness of the shifter cable. You can shift into a cog in the middle of range and visually inspect if derailleur is in line vertically under the cog that chain rests on. When derailleur is properly adjusted, ...


3

Since it only happens when you stand I would say it is definitely a combination of a worn chain and worn chainring, and nothing to do with shifters or derailleurs. As a chain wears, it 'stretches', meaning the distance between the pins in the chain grows. This is a result of the side plates wearing into the pin. Once the chain starts to 'stretch', it starts ...


3

Yeah, first clean the rear derailer well. Simplest way to do this is to lean the bike against a wall (outside, where you can make a mess), slide some newspapers up behind the derailer and drape them down the the wheel (to keep from dripping all over the tire), then spray the derailer well with WD-40, using an old toothbrush to clean it up a bit. ...


2

A friend of mine had a similar problem lately, and it turned out that her cable was damaged in the housing and was slowly lengthening as it degraded. It took her several shops to find the problem, but eventually they did. Pulling the cable out of the sheathing is easy and should eliminate the cable as a possible culprit.


2

My guess is that your bike simply needs a tune-up. A worn chain can indeed cause the problems you describe, and replacing a chain is fairly inexpensive, compared to other repairs to address this. If a worn chain is left on a bike for too long, these problems can become permanent, requiring the replacement of drivetrain gears. How long was this going on ...


2

Besides what is discussed here it could also be that the back derailleur dropout or the derailleur itself has been bent. If that's the case you won't be able to set up gears properly until it has been aligned. Even it's a new bike it only takes once hitting the wrong place to bend it :(. You can find a number of videos on the net on how to align the ...


2

Need better pictures to get a clear idea as to what is going on here, but assuming that the chain tension is good and the derailleur spring is okay, I'd check to make sure your derailleur hanger is straight. Especially on older derailleurs, this can allow the chain to be received by the cogs at an angle whereby the cog above and/or cog below can 'trap' the ...


2

The fixed gear mechanism is very simple - the cog is wound onto its thread so that when you pedal forward you are tightening the screw (as well as moving the bike forward). The opposite is also true, when you apply backward pressure, you're not just stopping, you're trying to loosen the screw. Most often you won't budge the cog, but it is possible that a ...


2

sounds like your chainrings are worn. Look at the rings and see if they are "shark fin" shaped rather than symmetrical - a google image search for "worn out chainring" will show examples including some really, really worn out rings. The old worn out chain likely wore out the rings as well. I've had exactly what you're describing on a couple bikes and it ...


1

My first thought that with a new drive train this would be either: A bent derailleur hanger The rear shifter cable has an issue As you have had the hanger replaced recently I would tend to think that it was likely that it is a cable issue. The first thing I would do is inspect the cable and make sure it is moving freely in the housing and there is no ...


1

Although this has been answered I thought I'd chuck another suggestion in there. As Mac said there is a difference between chainrings meant for deraileurs and those meant for single-speeds. That's not to say you can't use the former without a deraileur, but as it is easier to derail the chain you should check your chainline is well set up. If your front ring ...


1

The smallest cog appears to be rather badly worn (hard to say for sure without a shot from the side) and the second smallest is sorta worn, but otherwise the cluster doesn't appear to be very worn at all. I do note that in your shots you have the front on the granny and the rear on the small cog, meaning that your chain tension is very low. One generally ...


1

I had this trouble, and after checking the usual suspects (Replaced chain, cassette, cables, housing, and derailleur), it turned out my frame was failing near the bottom bracket. Although it's the most expensive to fix: before you start replacing components, do a quick visual inspection of the frame. Look for cracks/separations around the rear triangle. ...


1

I had a similar problem on my mountain bike. My bike is a 2008 Giant trance x2. It would "ghost shift" under load usually going uphill. It would even miss shift locking the back wheel. Very frustrating. I took it to my local bike shop and they did some adjustments and replace the chain. Resulting in a little improvement but still basically unrideable. I ...


1

I think it could be a few things. Loose / damaged bottom bracket. The play in the crank would cause some ghost shifting. Frame flex or damage. As you stand steel bikes flex, and can cause alignment issues (but should be within reason, unless there is damage loose rear derailleur Check for flex or looseness in the cranks and bottom bracket. Does it ...


1

You can have either of two situations: The chain is actually shifting from one sprocket to another. The chain is slipping on the sprocket, without shifting to another sprocket. The first case may simply indicate that the derailers are not properly adjusted (or may be due to worn components). The second case indicates that either the rear derailer does ...



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