Slipping chain and other questions
10-27-18, 10:12 PM
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Slipping chain and other questions
I have a Schwinn Discover men's 700c comfort bike I bought new a year ago. It's pure crap in quality (not your grandfather's 1960's-1970's Schwinn Varsity ten-speed made in Chicago, not by a damn sight) but that's another story.
1. slipping chain: only in 7th gear does the chain seem to randomly skip over the teeth of the rear cog while pedalling hard: the HIGH limit screw on the derailleur is perfectly adjusted and the bicycle shifts into all other gears and stays firmly meshed without ever skipping a beat: I noticed that at least one of the chain links binds when bent over by hand during close inspection: some of the teeth on the seventh cog look twisted while others look straight
Should I replace my freewheel and chain with a high-quality aftermarket parts? I've already replaced my solid rear axle with a chrome moly one by Wheels. Is there a way to fix a chain link so it doesn't bind? The Schwinn brand aluminum frame from Pacific Cycles is nice but it seems like they use junk components. Typical Walmart crap.
2. replacing the stock handlebar to a high-rise one to give my rheumatoid arthritis (lower back) some relief while riding I also get pain in my arms, neck, wrists and hands from leaning forward into the grips. Tingling in my arms and hands from loss of circulation due to supporting my upper body weight on the grips. It would be nice if the grips came more rearward with a handlebar conversion as well.
Is it true that the rule of thumb is for each and every inch of handlebar rise increase, movement of the grips forward or rearward and width increase the brake/shift cables should be one inch longer than stock? If I were to increase the handlebar rise by five inches, for instance, the cables/housings should be five inches longer than original? I want control cables that are just the right length. Not too much slack or too tight around turns.
1. slipping chain: only in 7th gear does the chain seem to randomly skip over the teeth of the rear cog while pedalling hard: the HIGH limit screw on the derailleur is perfectly adjusted and the bicycle shifts into all other gears and stays firmly meshed without ever skipping a beat: I noticed that at least one of the chain links binds when bent over by hand during close inspection: some of the teeth on the seventh cog look twisted while others look straight
Should I replace my freewheel and chain with a high-quality aftermarket parts? I've already replaced my solid rear axle with a chrome moly one by Wheels. Is there a way to fix a chain link so it doesn't bind? The Schwinn brand aluminum frame from Pacific Cycles is nice but it seems like they use junk components. Typical Walmart crap.
2. replacing the stock handlebar to a high-rise one to give my rheumatoid arthritis (lower back) some relief while riding I also get pain in my arms, neck, wrists and hands from leaning forward into the grips. Tingling in my arms and hands from loss of circulation due to supporting my upper body weight on the grips. It would be nice if the grips came more rearward with a handlebar conversion as well.
Is it true that the rule of thumb is for each and every inch of handlebar rise increase, movement of the grips forward or rearward and width increase the brake/shift cables should be one inch longer than stock? If I were to increase the handlebar rise by five inches, for instance, the cables/housings should be five inches longer than original? I want control cables that are just the right length. Not too much slack or too tight around turns.
Last edited by JonBailey; 10-28-18 at 12:49 AM.
10-28-18, 01:11 AM
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The slipping chain is probably because the smallest cog (I'm assuming the 7th speed cog is the smallest) is worn. The smallest cog wears faster than the others with equal use, because wear is spread over a smaller number of teeth. A new freewheel / cassette (don't know which type your bike has) is cheap, and a 7-speed chain is even cheaper. They're wear items, I would replace both.
Cable length: the rule of thumb you're quoting sounds reasonable, but I think you're better off following this advice: https://www.sheldonbrown.com/cables.html. Anyway, I would not try to calculate cable lenth before putting on the new handlebars. Cables are sold by the metre anyway, I'd just get a couple of meters of new brake cable housing, put on the new handlebars, and then cut the housing to size. It's much easier to get the cable length right when the new bars are on the bike and you can try the cable on for size.
Cable length: the rule of thumb you're quoting sounds reasonable, but I think you're better off following this advice: https://www.sheldonbrown.com/cables.html. Anyway, I would not try to calculate cable lenth before putting on the new handlebars. Cables are sold by the metre anyway, I'd just get a couple of meters of new brake cable housing, put on the new handlebars, and then cut the housing to size. It's much easier to get the cable length right when the new bars are on the bike and you can try the cable on for size.
10-28-18, 01:41 AM
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The thing is Pacific Cycles (they also sell the Mongoose brand) just sent me a "brand new" chain and freewheel last month while still under warranty. A while back, my bike was clunking while pedaling in just 4th and 5th gears. My local bike mechanic said I needed a new freewheel and chain which did solve the noise issues. My bike mechanic told me I have a freewheel, not cassette: I know this for fact. Cheaper dept. store bikes likely have freewheels. I think the Pacific Cycle components are just crappy by design. My derailleurs are genuine Shimano, however.
As far as the cables go, I will only need to replace the front cable housings since all the cables routed to the rear brakes and both derailleurs are exposed in the midsection of the frame.
My local bicycle project organization which I am a member should have bulk cable housing in stock and perhaps extra-long cables which can be cut to correct sizes. I'll have to ask them. Their mechanics might also be able to help me size the new cables for correct fit.
One more thing that just struck me....
I just readjusted the rear derailleur position on the hanger bolt too. The other day, the top of the cage plate was hitting the mounting bracket near the dropout thus causing the derailleur to not move into 7th gear, smallest cog. I had loosened this 5 mm hex screw and pivoted the derailleur all the way down so the jockey (upper) pulley was farthest away from the cogs. This is when I noticed the chain skipping trouble but only in 7th. I readjusted the derailleur mounting so the top of the cage plate (pulley guard) is close to the bracket but will still sufficiently clear it to shift into 7th. This readjustment moves the upper pulley close to the cogs so as to better align the chain with the cog teeth. My theory is that if there is too much slack chain between the upper pulley and the cogs, the excess chain may flop around causing the link rollers to miss the cog teeth occasionally to result in a slip (temporary chain derailment) during hard fast pedalling. The jockey is what precisely guides the chain links to mesh with cog teeth. I am going to see how seventh gear works now later on.
Sometime later....
No, the chain still skips over the teeth of 7th gear at random. Must be bad teeth on that particular Chinese-made cog. I can get by without 7th gear if push comes to shove anyway. This is a 21-speed model. 99% of the time the bicycle is no higher than 5th gear and in 4th gear more often than any other gear. I do need 1st occasionally to climb a river bridge with a steep-arched deck. Most of Boise Idaho's river Greenback bikeway relatively flat with a slight grade going up river east.
I sure miss those 3-speed bikes of old.
As far as the cables go, I will only need to replace the front cable housings since all the cables routed to the rear brakes and both derailleurs are exposed in the midsection of the frame.
My local bicycle project organization which I am a member should have bulk cable housing in stock and perhaps extra-long cables which can be cut to correct sizes. I'll have to ask them. Their mechanics might also be able to help me size the new cables for correct fit.
One more thing that just struck me....
I just readjusted the rear derailleur position on the hanger bolt too. The other day, the top of the cage plate was hitting the mounting bracket near the dropout thus causing the derailleur to not move into 7th gear, smallest cog. I had loosened this 5 mm hex screw and pivoted the derailleur all the way down so the jockey (upper) pulley was farthest away from the cogs. This is when I noticed the chain skipping trouble but only in 7th. I readjusted the derailleur mounting so the top of the cage plate (pulley guard) is close to the bracket but will still sufficiently clear it to shift into 7th. This readjustment moves the upper pulley close to the cogs so as to better align the chain with the cog teeth. My theory is that if there is too much slack chain between the upper pulley and the cogs, the excess chain may flop around causing the link rollers to miss the cog teeth occasionally to result in a slip (temporary chain derailment) during hard fast pedalling. The jockey is what precisely guides the chain links to mesh with cog teeth. I am going to see how seventh gear works now later on.
Sometime later....
No, the chain still skips over the teeth of 7th gear at random. Must be bad teeth on that particular Chinese-made cog. I can get by without 7th gear if push comes to shove anyway. This is a 21-speed model. 99% of the time the bicycle is no higher than 5th gear and in 4th gear more often than any other gear. I do need 1st occasionally to climb a river bridge with a steep-arched deck. Most of Boise Idaho's river Greenback bikeway relatively flat with a slight grade going up river east.
I sure miss those 3-speed bikes of old.
Last edited by JonBailey; 10-28-18 at 04:04 AM.
10-28-18, 02:58 AM
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The slipping chain is probably because the smallest cog (I'm assuming the 7th speed cog is the smallest) is worn. The smallest cog wears faster than the others with equal use, because wear is spread over a smaller number of teeth. A new freewheel / cassette (don't know which type your bike has) is cheap, and a 7-speed chain is even cheaper. They're wear items, I would replace both.
Cable length: the rule of thumb you're quoting sounds reasonable, but I think you're better off following this advice: https://www.sheldonbrown.com/cables.html. Anyway, I would not try to calculate cable lenth before putting on the new handlebars. Cables are sold by the metre anyway, I'd just get a couple of meters of new brake cable housing, put on the new handlebars, and then cut the housing to size. It's much easier to get the cable length right when the new bars are on the bike and you can try the cable on for size.
Cable length: the rule of thumb you're quoting sounds reasonable, but I think you're better off following this advice: https://www.sheldonbrown.com/cables.html. Anyway, I would not try to calculate cable lenth before putting on the new handlebars. Cables are sold by the metre anyway, I'd just get a couple of meters of new brake cable housing, put on the new handlebars, and then cut the housing to size. It's much easier to get the cable length right when the new bars are on the bike and you can try the cable on for size.
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10-28-18, 07:28 AM
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1. You say that your chain has one link that feels wonky. Try this:
Lean your bike up against something so you can turn the pedals backward with your hand. As you turn the pedals, watch where the chain exits the derailleur. If you see the derailleur arm move, that's it! You have a tight link. That's a common problem and is most likely to show up when on your smallest rear cog. Work that link back and forth sideways with your hands until it loosens up and you'll be good-to-go. It's common, by the way, for a freewheel cog to have some individual teeth that are different from the others. That's a design feature to make it shift better.
2. I'm thinking that you're 1:1 ratio of handlebar rise to cable housings length might not be right. You also have to account for the front-to-back handlebar placement. Also, since you are changing handlebars, the rule of thumb is the wider the bar, the greater sweep angle you'll want on the grips. Make sure the hand grip area of your bars is wide enough for your brake levers, shifters and hand grips.
Cables and housings typically are sold with extra length so they can be custom fit while being installed on your bike. The right length is the shortest that still allows you to rotate your handlebars all the way from side to side. You need to be very picky about cutting the housings square and burr free and you need to get a good, clean cut on your control wires.
Lean your bike up against something so you can turn the pedals backward with your hand. As you turn the pedals, watch where the chain exits the derailleur. If you see the derailleur arm move, that's it! You have a tight link. That's a common problem and is most likely to show up when on your smallest rear cog. Work that link back and forth sideways with your hands until it loosens up and you'll be good-to-go. It's common, by the way, for a freewheel cog to have some individual teeth that are different from the others. That's a design feature to make it shift better.
2. I'm thinking that you're 1:1 ratio of handlebar rise to cable housings length might not be right. You also have to account for the front-to-back handlebar placement. Also, since you are changing handlebars, the rule of thumb is the wider the bar, the greater sweep angle you'll want on the grips. Make sure the hand grip area of your bars is wide enough for your brake levers, shifters and hand grips.
Cables and housings typically are sold with extra length so they can be custom fit while being installed on your bike. The right length is the shortest that still allows you to rotate your handlebars all the way from side to side. You need to be very picky about cutting the housings square and burr free and you need to get a good, clean cut on your control wires.
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10-28-18, 08:45 AM
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1. You say that your chain has one link that feels wonky. Try this:
Lean your bike up against something so you can turn the pedals backward with your hand. As you turn the pedals, watch where the chain exits the derailleur. If you see the derailleur arm move, that's it! You have a tight link. That's a common problem and is most likely to show up when on your smallest rear cog. Work that link back and forth sideways with your hands until it loosens up and you'll be good-to-go. It's common, by the way, for a freewheel cog to have some individual teeth that are different from the others. That's a design feature to make it shift better.
2. I'm thinking that you're 1:1 ratio of handlebar rise to cable housings length might not be right. You also have to account for the front-to-back handlebar placement. Also, since you are changing handlebars, the rule of thumb is the wider the bar, the greater sweep angle you'll want on the grips. Make sure the hand grip area of your bars is wide enough for your brake levers, shifters and hand grips.
Cables and housings typically are sold with extra length so they can be custom fit while being installed on your bike. The right length is the shortest that still allows you to rotate your handlebars all the way from side to side. You need to be very picky about cutting the housings square and burr free and you need to get a good, clean cut on your control wires.
Lean your bike up against something so you can turn the pedals backward with your hand. As you turn the pedals, watch where the chain exits the derailleur. If you see the derailleur arm move, that's it! You have a tight link. That's a common problem and is most likely to show up when on your smallest rear cog. Work that link back and forth sideways with your hands until it loosens up and you'll be good-to-go. It's common, by the way, for a freewheel cog to have some individual teeth that are different from the others. That's a design feature to make it shift better.
2. I'm thinking that you're 1:1 ratio of handlebar rise to cable housings length might not be right. You also have to account for the front-to-back handlebar placement. Also, since you are changing handlebars, the rule of thumb is the wider the bar, the greater sweep angle you'll want on the grips. Make sure the hand grip area of your bars is wide enough for your brake levers, shifters and hand grips.
Cables and housings typically are sold with extra length so they can be custom fit while being installed on your bike. The right length is the shortest that still allows you to rotate your handlebars all the way from side to side. You need to be very picky about cutting the housings square and burr free and you need to get a good, clean cut on your control wires.
10-28-18, 01:30 PM
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1- Any wear or tight link issues will be seen more easily in the smallest cog. The twisted teeth you likely noticed are where the cog is designed to shift, called a shift gate sometimes. As chains and cogs have gotten narrower and closer together the amount of off adjustment tolerance is reduced. I would trial slightly different high gear limit screw positions before spending money. I suspect the place you bought the bike from isn't of any help? A tight link can happen from a few different causes. Knowing which helps to decide if the link is repairable or better replaced. The first effort is to try flexing the chain sideways to loosen up the chain's side plates on their pin ends a tad. Many chain tools have a set of holding fingers to do this loosening with but using the controlled tool. The big concern with the chain's link is if the side plate is working it's self off one end of the pin. While the chain is still, sort of, in a continuous piece this separating apart link can cause a skip. But the concern is when the chain give out and pulls apart, usually at a moment of very high pedal pressure. (As in OUCH!)
2- What a lot of shop wrenches do for casing length when swapping out bars/stem or just replacing the casing is to hold the old casing up against the configuration. We will rotate the bars around to insure the casing length we judge to cut the new at allows complete movement. Often we see OEM lengths are too long and can accommodate some difference in lever/control locations with no added length. But it all depends. Like many situations one measurement is worth a thousand assumptions. Andy
2- What a lot of shop wrenches do for casing length when swapping out bars/stem or just replacing the casing is to hold the old casing up against the configuration. We will rotate the bars around to insure the casing length we judge to cut the new at allows complete movement. Often we see OEM lengths are too long and can accommodate some difference in lever/control locations with no added length. But it all depends. Like many situations one measurement is worth a thousand assumptions. Andy
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