Functional bicycle question (Need answer fast!)

Factual Questions
1

Hi, I guess this is a bit of a long shot, but I have a major problem.

My good friend built a bike for me a few years ago. I don’t drive, and it’s how I get around. I use it every day, all the time.

So recently he noticed my tire was dangerously frayed, and he brought me another one. I could certainly have put it on myself, but he offered to do it for me. Then somehow he ran into problems with the chain or something, and wound up having to take the derailleur apart. The next day while I was riding, far from home, the derailleur fell apart.

So I got another one somewhere, and he put it on for me. But now, the back wheel won’t “freewheel.” (pedal backwards.) I just can’t ride like that. See, when I come to a stop, I have my right foot up so i can prop on the curb; but then to push off again I need my left foot up because the streets are all banked … … well, if you know what I’m talking about, you understand.

Yes, I suppose I could re-learn my entire style of riding, but I don’t want to. I want my pedal to go backwards. It did it before. The only part that was changed was the derailleur. I asked him if I needed to get a different one to make it work, and he said that wouldn’t help.

He said, well, you could always pick up the back of the bike and lift the pedal with your hand.

I said, while I’m riding it?

He said, no, whenever you stop.
Grrrrrrr! Can someone kindly explain to me what is likely to be the trouble here (besides him) and what I need to do to fix it?

Thank you so, so much. It’s my ride, man.

2

First, I can’t see how changing a tire would ever involve taking the derailleur off, much less apart. But if that is all that was worked on (besides the tire itself) then I’d guess that maybe the chain wasn’t put back on the right way through the jockey pulleys and that it simply jams when you backpedal or try to freewheel.

When you are riding, does the bike shift normally?

When you say the friend built the bike for you, did he build it up from a bare frame or did he simple finish assembling a bike that was shipped in a box mostly assembled? Because I can’t see someone able to build a bike from a bare frame allowing this to happen.

3

Can you still coast without pedaling? I’m having a hard time picturing a situation that would let you coast, but wouldn’t let you pedal backwards.

4

Oh, and if it is the chain installed wrong, taking the chain apart and re-threading it the right way through the derailleur would be the way to fix it. You would need a chain tool for this, unless you have a quick link on your chain (which makes it easier to fix).

But I think you really need a better mechanic, or learn to work on the bike yourself. Well worth it if the bike is your ride. And it’s not too difficult to learn.

Edit: ObligatorilySheldon Brown link.

5

Sounds like the idler wheel on the derailleur is too close to the teeth on the freewheel. Probably the donor bike had a different sized freewheel. Flip the bike upside down and pedal gently while shifting. If you can’t sort this out with a screwdriver in 10 minutes, you’d better pop into the bike shop and give them their $15 before you break some spokes by backpedaling and jamming the chain.

6

Well okay, that’s what happens sorta when i go to backpedal (even though I know I can’t now, it’s a long-standing reflex) – the chain goes slack, and then gets jammed between the sprocket and the hub. Every Time. It is unbelievably frustrating; I had to stop, loosen the quick release, yank the chain back out and put it on the sprocket, then tighten the quick release back up – six times on my way to work the other day.

Yes, he built it from random parts. He’s an excellent mechanic ordinarily; I really don’t understand what the deal is.

The derailleur was taken apart, I believe, because the chain had gotten hopelessly kinked in that kind of way that makes you believe in evil gnomes. I have no idea how that happened. I know better than to even speculate. :eek:

I’m wondering, it’s definitely not that the chain is too long now somehow, right? it’s just supposed to advance going either direction, but only engage the bicycle wheel when going forward?

7

(Chronos, when I say “pedal backwards,” I’m not being accurate, my fault. What I mean is, when I’m stopped at a light and leaning against the curb, and I want my left pedal up to push off, but it’s down, I use my free foot to snag the pedal and bring it up, against the normal direction of rotation.)

8

Bike shop.

9

Sounds like the gears aren’t indexed quite right with the new derailleur. So you can pedal OK, and coast, but when you try and pedal backwards the mis-alignment of the gearing causes the chain to stall / skip / get jammed etc.

Sorting the gearing out is a quick and simple job for a bike shop, or your mate (might require new cables if old cables are contributing to the problem). The fact he hasn’t done it suggests that maybe the derailleur is incompatible with the rest of the drive train (# of gears, type of gears etc.). Again the bike shop should be able to advise here, and even sell you a new one :slight_smile:

10

I agree that this is almost certainly the cause - swapping the derailleur won’t have any effect on the freewheel, and the fact that you can coast but not pedal backwards confirms that that’s not the problem.

The same thing happens if, you are partway through changing gears when you stop at the lights - you can’t pedal backwards because the chain jams, but if you lift the back wheel slightly and pedal forwards, all is well.

11

The chain was getting kinked because the travel stop going into the small gear was not set properly. It allowed too much travel of the derailleur. The current problem may well be caused by the wheels on the derailleur not turning freely. They move when under the force of your pedal forward, but not when there is no load when you pedal backwards. It could also be that the alignment of the derailleur is off enough to bind the chain slightly. These are all basic adjustments than can be observed and corrected with the bike upside down and the pedal operated in both directions. Of course it must be free or you don’t turn the bike back upright until fixed.

12

One other thing that should be checked is the chain.
Chains stretch and wear out. At somewhere between 1,000-1,500 miles your chain will be at the point of needing replacement.
A stretched chain will act really strange, funny shifts, jams kinks etc.
Since you said that you ride everyday and the chain jammed, and now it won’t pedal backward I’m thinking that you have a bad chain possibly coupled with a bad adjustment.
Your local bike shop has a tool that measures chain wear and new chains are fairly cheap. A new chain makes a huge difference in how a bike shifts and rides.

13

Unfortunately, while new chains are cheap, whole new chainsets (chainrings/sprockets) are less so. And if you’ve been riding for a while with a worn chain, the teeth of the chainrings etc may well have worn down to fit the stretched chain, which means when you put a shiny new chain on it will skip. :frowning:

I ride about 100 miles a week and am fairly lazy about replacing my chain. I still have a brand new one sitting in the garage because when I put it on it skipped. So I am currently using the old, worn chain on the old, worn chainrings until the whole lot craps out…

14

You are exactly right. You can’t mix a new chain with worn gears without having a system that skips come gears. Use the old stuff until changing at least the chain and rear sprocket gears and any worn derailleur gears.

The OP’s case may have some mismatched parts in the derailleur itself causing binding or the derailleur may be the wrong size for the bike. But mostly it’s not functioning in both directions as it should and the cause is readily evident upon inspection with the bike upside down.

15

I certainly would not let him touch your bike again.

16

agree with responses given here.

he might be a better mechanic than you but he isn’t an excellent mechanic IMHO.

often you need 3 or 4 hands when changing a rear wheel and attempt to remount it. if he removed or dismantled the derailleur to make it easier then he might have created another problem.

it sounds to be the derailleur stops weren’t adjusted correctly on the replacement derailleur. also adjustments done on an inverted bike may not give the desired result on an upright bike or an upright bike with a load on the chain.

17

Oho! Derailleurs come in different sizes! That hadn’t occurred to me.

You know, I can change a tube and tire, I can install new brakes and adjust them, but derailleurs remain arcane and mysterious, probably only because I’ve never taken one apart. :slight_smile:

The chain has been skipping a lot, and I know my sprocket teeth are hella worn down. When I go by the bike shop to buy something and ask a question or two, they laugh at my bike because it’s so sad, LOL.

It’s the kind of bike you take down to that undeveloped tract of land and jump through the mud puddles when you’re a kid. It weighs a ton, but I don’t care because now I’m really strong from lifting it up the stairs with all my groceries on the handlebars.

It sounds like the general consensus is that adjusting the gearing is the thing most likely to result in success. The local bike shop is booked about two weeks ahead, so I guess I’m’a go turn my trusty steed upsidedown and see what I can do.

Many thanks, everyone. I’ll let you know what happens.

18

If it has indexed shifting, the shifter and the derailleur(s) have to match. Shimano, SRAM and Campy have different standards. I think they have each changed their standards over the years, and the 7,8,9, and 10 speed standards are different. Older derailleurs are not going to work right with an indexed shifter, especially not suntour or heurret (sp?) You need to use shifter cable housing on the shifter cables…it stays the same total length when it flexes.

If it is an old bike with 8 or fewer rear cogs, I would just set it up with friction (not indexed) shifters to avoid all these issues…course then you have to know what to listen for so you can shift by ear.

Oh, and if the sprockets are worn well down, the only real cure is new sprockets and chain.

19

He has got the changer alignment wrong .

There should not have been a need to involve the rear derailler at all - well there is a type of derailler on really cheap machines that is mounted on a plate that is then mounted inot the rear wheel drop out, abnd its possible for the unskilled to get that wrong.

For most machines these days, the rear derailler is mounted into its own fitting just below the derailler, and there still should be no need to involve it when removing the rear wheel.

For your own safety, you must get it around to someone who does know what they are doing, the risk is that the chain could jam into the wheel and lock it up, and also tear some spokes out.

If we had some pictures to go on, a close up side shot of the derailler showing the chain passing around the jockey wheels, and also a picture of the hub area close up, from the back, then there is a chance of seeing what is wrong. but any half handy person would see the issue straight away.