Ask the Bicycle Mechanic

Miscellaneous and Personal Stuff I Must Share
81

[QUOTE=scr4]
He/she asked about the front derailleur; your answer only applies to the rear.

SRAM front derailleurs and shifters are compatible with Shimano MTB front derailleurs and shifters. It’s the Shimano road derailleurs that have different cable pull. I’d guess the bike shop replaced the derailleur with a Shimano road derailleur. Replacing it with a MTB derailleur (from either manufacturer) should solve this particular problem.

[/QUOTE]

Oops, you are right. My bad. You seem to be pretty knowledgeable about bikes.

82

[QUOTE=Triskadecamus]
What’s the cheapest reliable way to get a bike from DC, to San Francisco?

I am starting with my son’s bike (10 speed, not much in extras) in the living room, and I do not ride.

I get “estimates” of hundreds of dollars, and I have to pack it. Help, help!

Tris
[/QUOTE]

I don’t know if it is the cheapest, but I think Grey Hound is a good deal. I used their online quoting system, putting in Washington, DC to San Francisco, 40 pounds total, length of the box is 60 inches, and I got a quote under USD$60.

You can often get free cardboard bike boxes that the bike shops get their bikes in. They will also likely give you free packing material from when they unpack their bikes. At least that is what we did at my shop. If you want the shop to pack it for you, I suspect they will charge at least USD$20.

83

[QUOTE=Chasing Dreams]
You should get a high pressure hand pump
[/QUOTE]
Where would I find such a creature?

(And thanks, I never ever knew about the adjusting knob)

84

[QUOTE=NurseCarmen]
Where would I find [a high pressure hand pump]?
[/QUOTE]

Any bike shop, or any bike mail-order company (e.g. Nashbar). You probably want a “floor pump,”, i.e. a full-size pump for home and shop use.

85

[QUOTE=NurseCarmen]
Where would I find such a creature?

(And thanks, I never ever knew about the adjusting knob)
[/QUOTE]

I don’t know where you live exactly so I’m just going to throw a few suggestions out. The pump I use personally is Beto Floor Pump from Mountain Equipment Coop in Canada. In the states, you can try Performance Bike or Nashbar . For really good prices on all kinds of bike parts, visit Probikekit.com . Of course, you could always visit your local bike shop. Just make sure that the pump is rated for at least 120psi. You probably won’t find these kind of hand pumps in department stores.

86

[QUOTE=antechinus]
86Kg
Shimano Tourney back derailer
Front chainring has 48-38
Back freehub cluster has 7-speed combination 11,13,15,18,21,24,26 - not sure of brand probably Shimano.
Bike should be making clean shifts.
Problem has always occured. When I replaced cluster, derailer and chain the problem continued.
I havent crashed my bike, although the frame has broken through fatigue. It was under warranty and replaced.
Back wheel is tight as a fishes arseh*le.
I asked this question here a while ago and someone suggested it was autoshift, but it seems to be more the gears slipping over the cluster.

This happens when I am on the smaller gears 11-15. I spend most of the time in 48 on the front.

As I write this I have just bumped into this article. Maybe it is chain wear. Maybe I need to clean my chain more often.

If I ride 10 km a day, how often should I clean my chain?
[/QUOTE]

You have quite the mystery here. If this problem has always occurred and still occurs after you swapped out all those components with new ones, and even using a new frame doesn’t solve the problem, then I would go see a shaman to see if you are cursed! :smiley:

With a 7-speed rear derailleur, autoshifting shouldn’t be an issue because it can handle a less accurate set-up than modern 9 and 10 speeds.

Either chain or cassette wear could be a factor and is often the cause of a skipping chain, but you said the problem still occurs after you replaced them so that has me stumped. How many kilometres ago did you replace them? Check out the Sheldon Brown page on chain and sproket wear, you see an image of a worn out cassette. Also, check to make sure that your front chainrings are still in usable condition and don’t look like shark teeth in profile.

I think the best route to go here, given what you have already done, is to put your rear wheel with the sprockets on another 7-speed bike that you know has a relatively new chain and no major shifting problems. Ride on that bike and see if there is any skipping. That way, you can isolate the problem to either your rear wheel/sprockets or to the frame of the bike.

If you ride about 10km a day on roads with the occasional wet ride, then I say you can get away with degreasing your chain every 3-4 weeks.

scr4, what is your opinion on this problem?

87

[QUOTE=Chasing Dreams]
You have quite the mystery here. If this problem has always occurred and still occurs after you swapped out all those components with new ones, and even using a new frame doesn’t solve the problem, then I would go see a shaman to see if you are cursed! :smiley:

With a 7-speed rear derailleur, autoshifting shouldn’t be an issue because it can handle a less accurate set-up than modern 9 and 10 speeds.

Either chain or cassette wear could be a factor and is often the cause of a skipping chain, but you said the problem still occurs after you replaced them so that has me stumped. How many kilometres ago did you replace them? Check out the Sheldon Brown page on chain and sproket wear, you see an image of a worn out cassette. Also, check to make sure that your front chainrings are still in usable condition and don’t look like shark teeth in profile.

I think the best route to go here, given what you have already done, is to put your rear wheel with the sprockets on another 7-speed bike that you know has a relatively new chain and no major shifting problems. Ride on that bike and see if there is any skipping. That way, you can isolate the problem to either your rear wheel/sprockets or to the frame of the bike.

If you ride about 10km a day on roads with the occasional wet ride, then I say you can get away with degreasing your chain every 3-4 weeks.

scr4, what is your opinion on this problem?
[/QUOTE]

I don’t actually degrease my chain at all, just spray with teflon lubricant every few weeks. Maybe I should invest in a coke bottle and degreaser, as per sheldonbrown.com’s suggestion.

88

[QUOTE=antechinus]
I don’t actually degrease my chain at all, just spray with teflon lubricant every few weeks. Maybe I should invest in a coke bottle and degreaser, as per sheldonbrown.com’s suggestion.
[/QUOTE]

That would be a good idea.

Perhaps your chain is really, really, really, really dirty and that is causing it to skip. But for this to happen, you would have to work really hard at not washing it or like to ride through mud a lot.

89

[QUOTE=Chasing Dreams]
http://www.parktool.com/repair/. It’s a very good and detailed website.
[/QUOTE]

Bookmarked. Definitely useful so that I don’t have to go to a mechanic for the simpler stuff.

90

My bike (a beat up old Magna mountain bike I got from a friend when he upgraded) tends to skip in fourth gear (you’re peddling along and suddenly, for just a moment, the pedals are giving no resistance.) I never experience this problem in other gears. What could cause this?

91

We bought two Trek hybrids several years ago for cruising around town. We rode them twice, and they’ve been standing upright in the shed ever since. The tires, of course, are flat. What should we tell our local bike doc about getting the bikes roadworthy again? Thanks for your help!

92

[QUOTE=Lord Il Palazzo]
My bike (a beat up old Magna mountain bike I got from a friend when he upgraded) tends to skip in fourth gear (you’re peddling along and suddenly, for just a moment, the pedals are giving no resistance.) I never experience this problem in other gears. What could cause this?
[/QUOTE]

You most likely have a worn out fourth gear. To confirm this, look at the profile of the teeth on the fourth gear compared to the teeth on the other gears. A worn out gear will tend to have shark-like looking teeth. A new gear will have a flat top to the teeth. Take a look at http://sheldonbrown.com/chains.html#wear for a picture.

The reason that only the fourth gear is skipping is likely because your friend preferred the gear ratio that it provides. Thus, he used that fourth gear more often than the other ones and wore it out more. This happens to me too because there are 2 or 3 gears in the back of my road bike I prefer to use over the other one.

The only solution to this problem is to replace the worn out gear. You will most likely have to replace all the gears in the back because you either have a freewheel type gear that can only be replaced all at once, you are not going to find a bike shop that will only sell you one gear for an old bike, or you have a modern cassette type gear and the fourth cog is fixed to the other big cogs.

You may also have to replace the chain because it will have stretched from all the use over the years. Using your old chain with new gears will likely cause skipping.

If your bike is 7 or 8 speed, you can likely find cheap parts. You could go as cheap as CDN$10 for the chain and CDN$20 for the gears itself. Installation is extra but shouldn’t cost very much if you buy your stuff at a bike shop and get them to install it.

93

[QUOTE=DurbBook]
We bought two Trek hybrids several years ago for cruising around town. We rode them twice, and they’ve been standing upright in the shed ever since. The tires, of course, are flat. What should we tell our local bike doc about getting the bikes roadworthy again? Thanks for your help!
[/QUOTE]

I would recommend that you pump up the tires on your bikes and give them a quick inspection before heading out to the bike shop. Since you only rode them twice, there is a good chance they only need minor fixes. The grease and bearings on your bike should still be alright since they haven’t seen many miles. Take a look at the side wall of your tires. If they look wrinkly and have lots of cracks in the rubber, it is time to replace them. Look at your chain and gears, if there is lots of rust, then it is a good idea to replace them. However, they will most likely look new and just need some bike lube sprayed on them. Try taking out your seat post, just to make sure that it hasn’t seized up in the seat tube. Take your bikes out for a short spin and shift gears and pull on the brakes to loosen up the cables. Spray some lube on the metal of the cables if needed. If you really want to be safe, you could go around your bike with some allen keys and make sure all the bolts are tight.

If you don’t know what needs to be done to fix up your bikes so that they are good for cruising again, I would recommend you just pump the tires up and ask the mechanic at the bike shop to see what needs to be done. I think they would most likely recommend a minor tuneup since you kept the bikes in a shed. Tell them that you haven’t ridden the bikes much and they have been kept in storage. They will tell you if you need to replace anything.

94

Any suggestions for bikes for fat folk? Do they make reinforced frames, wheels, etc?

(Before anyone gets mad, yes I AM a fat man, who would lke to get back into biking.)

95

I have recently started cycling to and from work. It works out at about 50 miles a week, on flat terrain, and I have brought my old mountain bike out of semi-retirement. It dates from about 1990-91 and it was a decent bike in its day (a GT Karakoram, cost about 550 GBP new).

I lubed it up and it works fine, however, a couple of questions:

  1. How much have gears etc changed since 1990? Will I still be able to get spares that work with the Shimano Deore XT shifters (they are the more modern, for the time, type with two levers, one pushed with the thumb anmd one flicked back with the forefinger) and LX rear derailleur? (The original rear derailleur got mashed only a year or two after I got the bike, so the replacement is almost as old.)

  2. I get a really annoying creaking sound from the handlebars and/or stem when I put a lot of weight on the handlebars, e.g. standing on the pedals and riding hard, or pulling the front wheel up kerbs etc. I can’t figure out where exactly it is coming from - I don’t think it is the headset and it seems to be more from where the stem grips the handlebars. I have tighhtened up all the bolts firmly - I don’t want to overdo the stem bolts in case I crush the handlebars - but the clicking still drives me nuts. Any ideas?

lawoot, I wouldn’t worry too much about breaking a bike. Mountain bikes can withstand fairly well-built mountain-bikers doing crazy jumps and drop-offs etc., which surely put more stress on the bike than a fat man riding relatively sedately.

96

[QUOTE=lawoot]
Any suggestions for bikes for fat folk? Do they make reinforced frames, wheels, etc?
[/QUOTE]

MTB frames should be strong enough. You can get tandem-rated wheels if necessary, but a good set of standard MTB wheels should be fine.

Whether your body can handle the small bike seat is another matter - it’ll take a while to get used to. You’d probably be more comfortable on a recumbent bike (example).

97

[QUOTE=Colophon]

  1. How much have gears etc changed since 1990? Will I still be able to get spares that work with the Shimano Deore XT shifters (they are the more modern, for the time, type with two levers, one pushed with the thumb anmd one flicked back with the forefinger) and LX rear derailleur? (The original rear derailleur got mashed only a year or two after I got the bike, so the replacement is almost as old.)

  2. I get a really annoying creaking sound from the handlebars and/or stem when I put a lot of weight on the handlebars, e.g. standing on the pedals and riding hard, or pulling the front wheel up kerbs etc. I can’t figure out where exactly it is coming from - I don’t think it is the headset and it seems to be more from where the stem grips the handlebars. I have tighhtened up all the bolts firmly - I don’t want to overdo the stem bolts in case I crush the handlebars - but the clicking still drives me nuts. Any ideas?
    [/QUOTE]

(1) I’m assuming that you have a 8 or 9 speed cassette drivetrain on your bike. If so, you don’t have to worry about getting spare parts that will work on your bike because they are still commonly sold, ie: Performance Bike and Bike Parts . The stuff you buy today probably won’t match the finish of the components on your bike, but that is a minor issue. Even if you have a 7 speed bike, you don’t have to worry much because bike shops will often have some stock in the back and you can buy 7 speed stuff over the internet without much trouble.

The basic design of the gear train on a mountain has remain fairly constant from 1990 with some refinements. I’m not sure of the exact year when some of the bigger stuff became common but mtb gears went from 8 to 9 speed, indexed shifting became common, Shimano introduced profiling of the gears and chain that helps you to shift under load, and there has been a wide variety of “shifter pods”. Of notable importance, Shimano has a mountain bike shifter pod integrated with the brake levers where the brake levers are used to shift the gears and brake at the same time. They also have derailleurs that are reverse-rise, where lower cable tension causes the rear derailleur to shift to a lower gear instead of a higher one.

Another thing you should know is that SRAM is now a major player in the mountain bike gear train market, so you have more choice. Some of SRAM’s rear derailleurs use different cable pull ratios than Shimano so you have to check for compatibility before you buy. Other than that, high-end drive train parts generally weigh less now than they did in 1990 due to the usage of titanium/carbon fibre.

(2) Creaks are really annoying on a bike. The hollow tubing carries noise easily from one part to another so a squeak at your handle bar could be coming from your front hub! :eek:

However, we will assume it is coming from the handlebar area for now. I assume that you are getting the squeak when your hands are on the flats of your handlebar and not on some bar ends.

Either the squeak is coming from a cracked part on your bike or something needs to be greased. If there is a crack, it is likely to be at either the stem/handlebar interface, stem/steerer tube interface, where the down tube meets the head tube, or where the steerer tube meets the fork legs.

Checking for cracks will mean that you will have to take your stem off and pop out your fork a little bit to take a good look at the contact surfaces.

However for starters, I would just take the bolts off of the face of your stem and lube them with grease. While the handle bar is off, use a pencil and rub the graphite on the handlebar / stem interface. You could also do this at the stem / steerer tube interface. The graphite acts as a solid lubricant but it won’t cause your bars to slip when you yank on them. You don’t need a thick layer, just rub until you see some darkness on the interfaces.

98

[QUOTE=lawoot]
Any suggestions for bikes for fat folk? Do they make reinforced frames, wheels, etc?
[/QUOTE]

Either a recreational mountain bike or a comfort / city bike would be best for you. These two categories tend to have the handle bars placed higher up with respect to the seat. This would be important for you because it might cause you discomfort if you try riding a racing oriented cross country mountain / road bike where the handlebars are often meant to be placed lower than the seat. Once you lose some weight from the abdominal area, then it would become comfortable for you to lower your bars and become more aerodynamic.

With comfort / city bikes, they generally come with wide seats and some have suspension in the seat post so they may be more comfortable for you.

Try a Trek 4300, Trek 7100 , or Giant Sedona DX for starters.

You could always upgrade the components on your bike for sturdier ones if you find them too flimsy. Your local bike shop will likely have wheels meant for tandem bikes that have 40+ spokes each that you could buy if you desire. Virtually everything on the bike is upgradeable to something more substantial. The mechanic at your local bike shop would be the best person to ask for advice.

If you are really worried about strength but just want a recreational bike, then take a look at the 2007 Specialized Hardrock Sport . I have one as my commuter bike and it is beefy. However, it is somewhat heavy and slow.

99

[QUOTE=Colophon]

  1. I get a really annoying creaking sound from the handlebars and/or stem when I put a lot of weight on the handlebars, e.g. standing on the pedals and riding hard, or pulling the front wheel up kerbs etc. I can’t figure out where exactly it is coming from - I don’t think it is the headset and it seems to be more from where the stem grips the handlebars. I have tighhtened up all the bolts firmly - I don’t want to overdo the stem bolts in case I crush the handlebars - but the clicking still drives me nuts. Any ideas?
    [/QUOTE]

BTW, I forgot to mention that I wrote my previous response assuming you have a threadless stem. If you have a threaded stem, you should still grease your bolts and rub the graphite from a pencil at the stem / handlebar interface. However, for the portion of the stem that goes inside the steerer tube, you should put some grease on that big long bolt and inside the steerer tube to prevent any creaking.