What'd I do to my bike?
June 17, 2012 5:23 PM
I changed my bike tire for the first time. Now my shifter/derailer isn't working properly.
My rear derailer isn't shifting to the top three gears any more. The shifter is just tightening up and refuses to shift that far. Things were working fine before and I don't remember doing anything that could have affected the derailer. What's going on and how do I fix it?
My rear derailer isn't shifting to the top three gears any more. The shifter is just tightening up and refuses to shift that far. Things were working fine before and I don't remember doing anything that could have affected the derailer. What's going on and how do I fix it?
I would guess your rear wheel isn't fully seated. Loosen the bolt/quick release, hold the bike upright and make sure that the wheel is all the way in the dropout (the part of the bike frame that the rear axle fits into) and then retighten.
posted by rockindata at 5:29 PM on June 17, 2012
posted by rockindata at 5:29 PM on June 17, 2012
I'm not really qualified to work on my own bikes, but I have a lot of tools which is almost the same. I usually start with Sheldon Brown's website as a guide, http://sheldonbrown.com/, which has very clear sections on derailer adjustment (under Gears & Drivetrain). Also: what rockindata said.
posted by startled at 5:31 PM on June 17, 2012
posted by startled at 5:31 PM on June 17, 2012
@rockindata,
Thanks that seems to have fixed it. I also observe though that the two lowest gears are also causing the chain to rub against the front derailer, which I don't recall happening before either. Reseating the wheel didn't fix this. Any ideas?
posted by prunes at 5:37 PM on June 17, 2012
Thanks that seems to have fixed it. I also observe though that the two lowest gears are also causing the chain to rub against the front derailer, which I don't recall happening before either. Reseating the wheel didn't fix this. Any ideas?
posted by prunes at 5:37 PM on June 17, 2012
Derailleurs have a limited range of motion, to keep them from shifting the chain right off either end of the gears. There are two screws on the derailleur that adjust this range. However, since it was working fine before changing the tire, you probably don't need to adjust these. Instead, as rockindata suggests, in replacing the tire you probably didn't get it lined back up with the derailleur correctly. If you reseat the wheel in the dropout, they should line up again. If not for some reason, then your second line of defense will be adjusting the derailleur.
posted by dendrochronologizer at 5:38 PM on June 17, 2012
posted by dendrochronologizer at 5:38 PM on June 17, 2012
What rockindata said, plus; go along your shifter cable from the shifter to the rear and make sure it’s all correct, in the guides like it’s supposed to be.
posted by bongo_x at 5:39 PM on June 17, 2012
posted by bongo_x at 5:39 PM on June 17, 2012
Well, derailleurs usually have a pair of screws that let you adjust the range they move through— maybe you need to tweak those a little.
posted by hattifattener at 5:39 PM on June 17, 2012
posted by hattifattener at 5:39 PM on June 17, 2012
I guess that's what the preview button is for
posted by dendrochronologizer at 5:40 PM on June 17, 2012
posted by dendrochronologizer at 5:40 PM on June 17, 2012
Do you have horizontal dropouts or vertical dropouts? If you have vertical dropouts, try pushing down with a bit of pressure on your saddle, open your quick release, and then close it again. This will let the axle seat better in the dropouts.
If you have horizontal dropouts, then it's probably that your wheel is not aligned properly. Loosen your axle nuts, align the wheel, and tighten again.
I work in a bike shop, and the last bike I worked on today was brought in for this exact same issue. The problem was that they weren't putting enough downward pressure on the bike while closing the quick release.
If you can post a pic of your bike, that would help a little.
posted by spikeleemajortomdickandharryconnickjrmints at 5:58 PM on June 17, 2012
If you have horizontal dropouts, then it's probably that your wheel is not aligned properly. Loosen your axle nuts, align the wheel, and tighten again.
I work in a bike shop, and the last bike I worked on today was brought in for this exact same issue. The problem was that they weren't putting enough downward pressure on the bike while closing the quick release.
If you can post a pic of your bike, that would help a little.
posted by spikeleemajortomdickandharryconnickjrmints at 5:58 PM on June 17, 2012
Don't tweak any other adjustments until you are sure everything else is back the way it is supposed to be. Rule of thumb: if it was in adjustment before you started, then it probably hasn't magically come out of adjustment. Much more likely that there is something that hasn't gone back together correctly. Or, the bike was setup with the wheel not properly bottomed out and slightly cockeyed, in which case a readjustment will be necessary.
posted by gjc at 6:50 PM on June 17, 2012
posted by gjc at 6:50 PM on June 17, 2012
I also observe though that the two lowest gears are also causing the chain to rub against the front derailer, which I don't recall happening before either. Reseating the wheel didn't fix this. Any idea
Don't adjust the screws on your derailer, they're a pain in the ass to get right. Do you know what type of gear shifters you have? Tension/friction (where you adjust by pulling them as much as you need) or index (where they make a click for each gear you shift)? If you have tension shifters, then you may just need to jiggle that a little bit.
It sounds to me like your rear tire is not in quite straight, putting everything out of alignment. If you lift up your bike from your seat, spin the rear wheel and eyeball the tire between the two rear fork pieces, does it look even to you?
posted by Think_Long at 6:56 PM on June 17, 2012
Don't adjust the screws on your derailer, they're a pain in the ass to get right. Do you know what type of gear shifters you have? Tension/friction (where you adjust by pulling them as much as you need) or index (where they make a click for each gear you shift)? If you have tension shifters, then you may just need to jiggle that a little bit.
It sounds to me like your rear tire is not in quite straight, putting everything out of alignment. If you lift up your bike from your seat, spin the rear wheel and eyeball the tire between the two rear fork pieces, does it look even to you?
posted by Think_Long at 6:56 PM on June 17, 2012
I have index shifters with horizontal drops. I'll try adjusting the alignment of the wheel.
posted by prunes at 7:14 PM on June 17, 2012
posted by prunes at 7:14 PM on June 17, 2012
Sorry for thread squatting here. I'm having trouble getting the alignment right... any tips for how to do this?
posted by prunes at 7:26 PM on June 17, 2012
posted by prunes at 7:26 PM on June 17, 2012
If you're having this much trouble, perhaps you have old-style horizontal dropouts? All you need to do is eyeball it. I use my fingers and the chainstays as a guide, one finger of space on the right, one finger of space on the left, then tighten down the bolts.
As for adjusting the derailer limit screws, don't. You run the risk of trashing your wheel and frame unless you know exactly *why* you're adjusting those screws. They did not move when you took your wheel off; your wheel is simply not seated the way it was before.
posted by jrockway at 7:48 PM on June 17, 2012
As for adjusting the derailer limit screws, don't. You run the risk of trashing your wheel and frame unless you know exactly *why* you're adjusting those screws. They did not move when you took your wheel off; your wheel is simply not seated the way it was before.
posted by jrockway at 7:48 PM on June 17, 2012
Turn the bike upside down and look down at the wheel to see how it is sitting between the stays. It should be equidistant between the two.
It you have a quick release loosen it off grab both sides, pull back as far as it will go then close it off. Check the alignment. If it's off it can be easier to grab the tire hard near the seat tube, loosen the quick release and adjust with the hand that has grabbed the tire.
If you have wheel nuts attaching it loosen them off, push back then tighten one side down. You can then adjust the alignment by grabbing the wheel near the seat tube and tighten the other nut down when it's done. Then go back and make sure the first nut is properly tight.
Two things to bear in mind: You wheel is dished i.e. one side is flatter than the other(though this should be obvious. Tires are not always exactly straight, this matters more if you are trying to judge if a wheels true, but if you can you should look at the rim to guide you.
posted by tallus at 7:50 PM on June 17, 2012
It you have a quick release loosen it off grab both sides, pull back as far as it will go then close it off. Check the alignment. If it's off it can be easier to grab the tire hard near the seat tube, loosen the quick release and adjust with the hand that has grabbed the tire.
If you have wheel nuts attaching it loosen them off, push back then tighten one side down. You can then adjust the alignment by grabbing the wheel near the seat tube and tighten the other nut down when it's done. Then go back and make sure the first nut is properly tight.
Two things to bear in mind: You wheel is dished i.e. one side is flatter than the other(though this should be obvious. Tires are not always exactly straight, this matters more if you are trying to judge if a wheels true, but if you can you should look at the rim to guide you.
posted by tallus at 7:50 PM on June 17, 2012
If the wheel is seated and aligned properly then you most likely whacked the derailleur. There's several things that can go wrong. You might have pulled the cable, causing it to slip (most likely), or you might have bent it. It's highly unlikely you adjusted the limit screws.
Adjusting derailleurs is not super hard but it is very hard to describe via text. It's also pretty hard if you don't have a bike stand, though it is doable. If you bent the derailleur, well... bending it back is actually doable but requires a skilled hand.
I'm not sure why everyone's so panicky about adjusting the limit screws. You cannot trash your wheel or frame. At worst your gears won't have full range of motion or the chain will pop off the gears. Neither of these is cause for panic.
Since I cannot show you how to fix it, I'd suggest taking it to a shop and signing up for a few bike repair classes somewhere. It's great fun.
posted by chairface at 7:59 PM on June 17, 2012
Adjusting derailleurs is not super hard but it is very hard to describe via text. It's also pretty hard if you don't have a bike stand, though it is doable. If you bent the derailleur, well... bending it back is actually doable but requires a skilled hand.
I'm not sure why everyone's so panicky about adjusting the limit screws. You cannot trash your wheel or frame. At worst your gears won't have full range of motion or the chain will pop off the gears. Neither of these is cause for panic.
Since I cannot show you how to fix it, I'd suggest taking it to a shop and signing up for a few bike repair classes somewhere. It's great fun.
posted by chairface at 7:59 PM on June 17, 2012
The bike is a mid 80s Japanese model, so yes I'm guessing it has the old-style horizontal dropouts. I don't think I whacked the derailleur but it's possible. I guess I'll just bring the bike to the shop and see what they say. I've played around with the wheel for a while now and still can't figure out how to align it properly.
posted by prunes at 8:04 PM on June 17, 2012
posted by prunes at 8:04 PM on June 17, 2012
FYI, the reason people are freaking out about the limit screws is if the low screw is too far out then you can destroy your rear wheel. Basically, if the screws are too far in, a few of your gears become inaccessible. If the high screw is too far out, then you can drop your chain. And if the low screw is too far out, you can shift your derailleur across the spokes of your wheel and rip out multiple spokes.
Some older bicycles come with a "pie plate" between the cogs and the spokes so that if you make this mistake, instead of crossing the spokes and ripping them out, the derailleur will just scrape on the plate. Fancier bikes omit the pie plate because these bikes are targeted toward people who know how to keep their limit screws set, or can afford the services of someone who does.
posted by d. z. wang at 8:48 PM on June 17, 2012
Some older bicycles come with a "pie plate" between the cogs and the spokes so that if you make this mistake, instead of crossing the spokes and ripping them out, the derailleur will just scrape on the plate. Fancier bikes omit the pie plate because these bikes are targeted toward people who know how to keep their limit screws set, or can afford the services of someone who does.
posted by d. z. wang at 8:48 PM on June 17, 2012
Oh, if you have horizontal (or semi-horizontal) dropouts then yes, there is going to be fiddling required to get things just right. Tighten, test, loosen, test, etc. I had an old miyata that had little screw-things that let you set the depth in the semi-horizontal dropout- but those are not super-common.
You can also look carefully at the paint and dust- it is sometimes quite obvious where the wheel commonly is normally bolted on from the lack of dirt/indentations in the paint.
posted by rockindata at 9:09 PM on June 17, 2012
You can also look carefully at the paint and dust- it is sometimes quite obvious where the wheel commonly is normally bolted on from the lack of dirt/indentations in the paint.
posted by rockindata at 9:09 PM on June 17, 2012
I also ride an 80's Japanese road bike, and whenever my shifters start missing gears it's always because one end of the relevant cable has come unseated from the little hole where it is supposed to live and has gotten wedged against the derailer/shifter itself (depending on which end) causing it to be slightly more tensioned than it should be. Check the cable and make sure that the little caps on the ends are properly seated in the little holes where they are supposed to go. If it's popped out, you should be able to simply pop it back in with a finger and hey presto! all will be well again.
posted by Scientist at 10:18 PM on June 17, 2012
posted by Scientist at 10:18 PM on June 17, 2012
This thread is closed to new comments.
posted by prunes at 5:25 PM on June 17, 2012