Miscellaneous Mechanical Ramblings
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Bottom Brackets I came across a good one the other day I was to change out a bottom bracket for a customer. It was a FSA ISIS bb. I took out the right had cup with a very large breaker bar with a 1/2" drive splined tool. Everything went along fine then I was starting to pull out the bb from the left side and it came out about 1/4" of a inch before I could feel it hit something. Since I felt this before I knew what to do. The little screw that holds the bottom bracket guide onto the bottom of the shell was too long and was hitting the bb cartridge as it was coming out. No big deal I just unscrewed that little bugger a few turns and boom out came the cartridge bb. If you feel some resistance always try and know why before you push past it.
Brake Squealing is one of those things you need to do some thinking before you mess up your brakes. Squealing is
sound. Not that hard yet, and sound is vibration. The vibration is carried through the air to your ears. Ok that is the hard
part. So where does that vibration come from? That is what you need to fix.
Most shops and people I know go right to the toe it in and if it does not get better just do it more because if a little
is good a lot must be great. Toeing in a brake is when you bend or on newer brakes just align the shoe so the front of the
brake shoe hits the rim a second before the back of the shoe makes contact with the rim. What this does is cause the two
brake arms to tighten up on the center bolt. Well that is great if that is were the squeal is coming from. But not great
if that is not were the sound is starting from.
Were I start is with the brand of the brake. Yes a cheap stamped out arm brake will almost always squeal so a small amount
of toe in is a good thing. If you are looking at a well made forged arm brake that is not were you want to go. Those arms
are so hard I have seen people crack the arm by trying that. So before you pull out the old trusty arm bender try
adjustment first.
The first thing I do for a real screamer is take it all apart and check all the parts are in there and that there is no
dirt is in between the arms. A small amount of dirt will allow the arms some movement and that will allow the screeching
sound. The proper adjustment point is were it will move freely but have no play with the spring not hooked up yet. After
I get to that spot I will say 90% of the squealing will be gone. I then put it back in the bike and see if both pads are
set parallel with the rim. Remember the pad may be worn at an angle or the center bolt may not be straight or the hole
in the fork may be off all of them will cause that noise to come back. Now check the brake pads are they like a rock.
Yes that will not be good either. Get some new rubber on there and now take it out for a spin. Is it all quiet yet. If
not try and see if it is the front or just the rear. Then What I do is try some different pads and I also try a different
wheel. All that an cause a squeal.. Good luck!
Carbon Cranks Creaking sounds like a bolt needs to be tighten up or maybe pedals need a dose of grease and re tightening. So I tighten up the chainring bolts then the crank bolts then the pedals. Guess what still creaking. The customer asked for a new bottom bracket to be installed. He bought it from me so I was going to get it warranted and warrant the labor. I put his bb in and a few days later he is back with the same creak. I ride it and recommended we try and different crank. I have a similar crank and put mine on his bike. Silence at last. It seems the aluminum inserts in the carbon FSA cranks moved ever so slightly. Well the good news FSA warranted the cranks I got my cranks back. All creaks that I can remember on bikes have always been movement. Cut out the movement and you can cut out the creaks.
Flats can be a problem or if you are like me and falling off the back a god send. But it seems so easy but I have had two this week that they were on a ride and forgot to find the reason for the flat and went through all the tubes they had. They called home got picked up and brought the wheels to me only to have me fined a thorn in one and a wire in other by rubbing my fingers in the inside of the tire. Take the time to search the tire with your finger tips and look at the out side of the tire. You can even match up the hole with the tire and see if it helps you too.
Flats 2 We recently got a problem I do not see to often. That is using the wrong size tube in a tire. It came this way from the factory and has been causing a lot of problems. The tube was too big. It was a 20x1.5 to 1.75 and needed a 20x1.3. So the tube folded over on it self and would develop these small blowouts but you could see these folds in the tube. We may never have figured it out until I got the customer to bring in the whole wheel and saw the tire was smaller then the tube. You can usually go to a thinner tube but should never go with a bigger tube.
Flats 3 One of the things that is nice, if anything is nice about flats, is the ability to "read" the flat. Almost all flats I have encountered leave very easy to "read" signs of what caused them. Which allows you to fix the cause very fast so the same thing does not happen again. But about 25% of the tubes I sell seem to be defective. I have had very few defective tubes out of the box in my many years of fixing flats and all of them were the valve. But the tubes I sell over the counter seem to have these unexplained big holes in them. If you think about the tube as a balloon how many times in your life have you blown up a balloon and found a hole in it. Never with me and my children. I will usually just warrant the tube as long as I get my say about what caused the hole. If the customer will listen they get a free lesson on tube installation and they get a new tube. But the best for everybody is they do not get that "defective" tube any more.
Frame alignment seems to be a dying art. An older woman came in the store the other day and was looking at bikes but kept complaining that they were not as good as her old bike. When I asked about her old bike she said that she hit it with her car and another shop said it could not be fixed. Being an arrogant old coot I said I could fix it just bring it in. Well I did fix it and it was a pain but not that bad and it was not that expensive to do. So if you love your bike and you should mess up the frame even if a few shops say "No way" keep looking they may be right but I feel everything can be fixed, it just has a cost. But most times it shows up as just does not feel right. Before you go out and start buying a new bike let some one that has the tools give it a look over and if you hear the word "no" look at another shop.
Front Derailleurs are one of the most misunderstood and hard to get right simple adjustments. Even on a new bike where you can be sure most of the parts are working. So much of the adjustments are things other then those two little set screws. A customer came in with a bike he had spent considerable time on the front derailleur and still could not get to work. After I spent about 1/2 hour of my time, more then it would take me to fix it, telling him what I will do to it. He left it for me to fix. Now remember this is on a new bike. I razed it up and twisted it so it would line up with the chain rings. Shortened the cable and housing and ran the cable over the pinch bolt and tab instead of under the pinch bolt tab. Then I readjusted the set screws to limit the travel. As repairs go not a big deal but how do I describe this with out doing it. I would love to show people but that would add to the time. My opinion is try it your self first but at some point find some one you trust and just let go.
Front Derailleur II When an older front derailleur stops working correctly and you know it is not the cable. I look at four things. The first one, is the outer part of the cage twisted in relationship to the chainrings. Look down from the seat to see this one. A problem that happens when your pants get caught in it. Second is the curve of the outer part of the cage bent up too high or curved down into the chain rings. It happens when something gets caught in there too. Third one is look inside the cage. Has the chain cut a grove into the cage? If you can not see try to feel it with your finger but be careful it may be sharp. The forth one has the front derailleur move straight down into the crank. Each has its own fix but it is a good place to start.
Greasing Threads Had a fun one last night we were trying to get a splined Shimano bottom bracket out of a trashed Serotta road bike. No matter how hard we twisted with 24 inch lever it would not move and yes we were doing it the right direction. So I pulled out a 1/2" air impact tool and that cup spun right out. After every body put their eyes back in their head we spent some time talking about the damage that one of these things can do. Some big powerful tools can be great but I would be very careful with them and this would have been mush easier if the original owner or shop tried greasing the threads first.
Handle Bars A customer came in with a problem the other day. His bars would drop down every time he put pressure on them. I looked at them and measured them up and even though he was told the clamp on the bar was the same as the handle bar they were not. Very close but not the same. I always try and match the bar and stem with the same brand. What ever brand you have stick with it. This problem seems to show up most in the old 26.0 size. A lot of the 26.0 are really 25.8 or 25.9 by my micrometer.
Installing Shimano splined crank arms I have seen a lot of damage Shimano splined crank arms out there and it looks like the problem is a simple one. When people start to install a crank arm that was pulled off using the one key release system that comes on a lot of upper end Shimano cranks. People try and put it back on with out removing the one key release system and it can be hard to feel for those splines. I always remove the one key release system with the little pin tool you get with the cranks or use the tips of a set of small needle nose pliers. It take a little longer but if you do not there is a good chance that you will slice a little of the aluminum spline in the crank and then you will get a nice creak that will never go away.
Pedal Threads. Even though I have never had a pedal come out from a crank that I installed new it happens a lot around here in Scotch Plains, I will not point any fingers. But, if the threads are greased and the pedals are tightened up correctly they just do not come out. If it does come out here is really only two things you can do one is buy another crank arm and the second is tap it out over size and in stall a treaded insert. I recently met some one that tried this method of melting at low temp a alloy of aluminum and some unknown metal with a propane torch and re cut the threads and it lasted only one day. So we are back to the insert but I will also say it is not very expensive and I have never had one of those fail yet. Where is that piece of wood to knock on.
Rapid Rise rear derailleurs by Shimano. For years now many component companies have tried to come up with a fix for the fact that the two shift levers on a bike work opposite of each other. It is not a problem to people that have enough miles on a bike but does seem to cause some concern to new riders. Years ago a company called Suntour came up with a fix to change the action of the front derailleur. It would pull the chain from the larger chainrings to the smaller ones. It did not do it well because a spring had to push the chain back up to the larger rings and under any kind of load it just did not work well. It was popular with low end bikes and if the rider wanted the derailleur could be changed to a standard one and because the shift lever was friction it was perfect again. Now enter the modern era "INDEX". Shimano did the same idea except they did it to the rear derailleur and named it "Rapid Rise". It works well the only problem I see is the same problem as before under load the spring will not push it back up as well. But with Shimano's pick up point on the gears it is much better then the older systems. The problem is with compatibility. There is none. I have put a non Rapid Rise rear derailleur on a Rapid Rise shifter and it worked the numbers just did not run true. So if you have to replace your rear derailleur or you shift lever make sure to get one that will work on the system you have because you can not switch or change the parts to the other way.
Seatpost 1 I do not care how good your eyes are you nor any one else can tell a 27.2mm seatpost from a 27.0mm post by looking at it with out help. So if you go into your local bike store and need a new seatpost please bring your old one in or your bike frame so they can measure the old one for you. Most seatposts come in 2 tenths of a mm difference that is like the thickness of two sheets of printer paper, yes I just measured it, so trust me when I say bring it in.
Seatpost 2 must be greased. I know it goes against most logic but a dry or not greased seatpost will slip more then a greased one. The dry post will develop small rust or aluminum oxide on the surface and that will allow the post to move around in the frame. Next if you do not grease the seatpost at some point in the future it will become one with the frame. I recommend putting some tape on the post to mark the height then pull it out, clean it then re grease it at least once a year. We include that on all the tune ups we do here at The Bike Stand.
Seatpost 3 The squeegee effect. This is were your seatpost is too long. Anything over 10 cm in your frame is too long. When you do as I say and grease your seatpost before you put it in but it is too long the grease will be dragged off the seatpost in the "squeegee effect" rendering the post with no grease at the bottom. When this happens you have a post that is frozen in your frame and is even harder to get out because there is so much contact between the frame and the post. So buy the correct size or cut it down so you have 10 cm or less in your bike. It will also make it lighter.
Seatpost 4 The carbon seatpost. I know carbon is so cool and so light but you have to understand that most frames are not designed for the proper clamping of a carbon seatpost. I have seen so many really expensive carbon post ruined by the frame and clamp. I would recommend some of the really light and oh so cool aluminum alloy post and just forget about using carbon there. If you want carbon you need to use special clamps like Campagnolo that helps spread the force around the whole post and not the back. You can also turn the clamp 180 degrees away from the slit in the seat tube and that helps too.
Shifting problems with Shimano STI. A few things could be making Shimano STI shift when you did not ask it to or not down shift at all. First and most simple is cable stretch. To check that shift it in to the smallest cog and make sure to push the smaller lever in a few extra times to make sure the derailleur is let all the way out. Hold the bike off the ground and shift the right lever one click. Now pedal it a few turns it should pop right up to the next gear. If it did not then you need to tighten the cable. If it does then you need to look at the friction in the cable by shifting down, still just holding the bike up in the air, and see how fast it moves down. It should drop right down in less then one turn of the cranks. If it does not then you need to oil or change the cable and housing or oil with a very light lube, not WD-40, the shifter pod in the lever. When the lube dries out it will not down shift well and you may down shift three clicks and it goes down two and you will feel the third later or called ghost shifting. Similar to that is a small kink in the cable or housing that really can only be fixed with new cable or housing. The last and does not happen very often is the pod needs replacing but about 90% just gets fixed.
Spokes Breaking I know no one wants to think it is their fault but there are people out there that just seem to break more spokes then others. I do not mean just bigger people either. I have a customer that seems to have problems with braking spokes on nice higher end wheels. I brought it up the other day it may be him. I can fix the wheel but he may just put more stress on his wheels then other people. I out weigh him by 30 lbs. and I can not even remember the last spoke I broke. If you are breaking spokes it may be the wheel was made poorly, it may have defects in materials, it may be the wheel is too light and it may be you ride hard.
Spoke Sizing remineds me a little of the seat post, they come in hundreds of different sizes and a few different gauges. I love the people that come in and want to buy a spoke and say it is for a 26 inch wheel. I am sorry but I still laugh a little at that point. After I apologize for laughing I explain why. By pulling out an older Sutherland's manual I look up 26 inch wheel size and point to the part where it says number of spokes, height of the hub flange, number of crosses, and brand and model of rim. Then I get that Oh I get it now look and they bring the wheel in. life is good again.
Stem Creaking most people know to grease the threads on the binder bolts on stems but not ever body knows to grease or oil the flats parts too. It goes against the grain to fix a creak in the stem with a lubricant but it works it also stops the bars from moving in the stem. Just really clean the bar stem connection real good then grease it up and tighten it down.
Stem to Handle Bar Sizing have become a nightmare to bike shops. It has always been bad you had a few different
French sizes a few different British sizes and a few American sizes too. My answer was to try and match brand to brand in
stems and bars. That helps some but not all. I will try and list all that I can about different sizes of stem and bars.
Remember you will need a set of very good measuring calipers to do this so if you need that go down to your favorite
bicycle shop and ask for help and if they help you maybe you should buy the parts from them too. And yes I think it is
getting better now.
Threaded Head sets it has come up again that the average person may not know all the fit problems associated with head sets. I will try and give some insight in to this. There is at least five different threads out there.
STI Shimano shifters not going back down again. First of all do not take it apart. That is a last ditch attempt because you probably will not get it together ever again. The first thing to do is get a clear picture in your head of how it works. There is a gear that has teeth in it that the paws fit into. The gear rotates one way by you pushing it up into a larger cog or chainring and a little spring pulls it back down the range. The spring can do its job when you push the lever in, it opens a paw up and the gear moves to the next paw. Sometimes you can get to the gear and see it happen. If you can, try spraying a penetrating oil in to it while you wiggle the paws with a pin. After a while the light oil will start to get into the smallest reaches of the pod and you will see it move up and down again. All the time you are doing this I also want you to be pulling on the cable when you are trying to shift it and also shift it hard really bang on it. By banging on it the paws start to loosen up faster. The spray lube I use is Tri-Flow, the best I can find, but any spray lube should work.
Tools 1 A fun one the other day a customer came in with and older style freewheel they bought on Ebay. And guess what he put it on himself with no grease and road it to see if the cogs where worn or not and then thought about if he could get it off or not. I was lucky enough to have the right tool for it but I would recommend have the source for the tool either at your local bike shop or your self before you need it.
Tools 2 A customer called my attention to the mess of tools on my bench. I quickly apologized for the mess and he quickly said "no I like that you do not just have the tools you use them." Well he made my day.
Tools 3 Just as a warning. If you buy a tool at my shop and use it. it is yours. I have had people buy tools tell me it did not work and want their money back. I would ask to see the bike to see if this was the case. When they said "no it does not work" I tell them there is no refunds for tools and please leave the store. Take some time and figure out if it works first before you buy it. I will show you how it fits, how it works and then sell you the tool. So if you think you can pull this one over on local shops think again.