I have a new bike and after a bikefit (it was causing me kneepain) I had to raise the saddle and noticed a crack. I only use a torque wrench and tighten it to 4Nm usually so I can't overtighten (4.5 - 5.5). Can someone tell me if I should be worried?
34150
Intended as a canonical answer to the many questions we have about damage to carbon parts. It is well known that carbon fiber parts can be damaged and fail, and carbon parts can be fragile when stressed in certain ways, but we get a large number of questions on this site asking if a carbon part (Frame, rim, stem) with damage is a concern or not.  Many of these parts are obviously suffering no more than a minor cosmetic blemish, and very few are suffering from clearly significant damage. Most fall into the gap between where physical inspection is required to make an assessment.
58811
Specifically when changing gears from middle chain ring to smallest, the chain will sometimes get 'sucked' up between the inner chainring and chain stay. It seems to happen more often in muddy conditions. I keep my drive train clean and lube my chain often.  I bought the bike new and maybe 1200-1500 miles on the original chain/derailers. I have swapped out the original (aluminum) inner chainring with a new steel chainring and still get chain suck.
28989
I have a kryptonite U lock and lately it's been sticking a lot while trying to turn the key. Usually I can eventually get the key turned. It was getting worse though and a few days ago I (unable to find any lube/wd-40 etc) cleaned it out with soap and water which seemed to help a great deal. I also started being very careful to make sure the little key-hole guard engaged. Last night when I was totally unable to get my bicycle unlocked and had to leave it there and walk home. The key would fit into the lock and turn half way and then stop. I'm going to go try and pick it up now, but I don't know the best way to try and make sure this doesn't keep happening. It's winter here and I wonder if that might have something to do with it.  Edit: I ended up at the hardware store and the guy there (who had built his own bike in his garage, conveniently) recommended jig-a-loo. This made the lock move really well but I still couldn't get it open. This is when I noticed that my key was twisted (From trying to force the lock probably). I flattened the key back in a clamp and was able eventually to unlock it, but I can't seem to lock it again, so I ordered new keys. I'll have to wait till they come to see if that solves anything or it's actually a problem with the lock...  Edit again: Some graphite and new keys seemed to do the trick!
111443
I have a question about my front derailleur sticking occasionally.  I've had this bike for a 1.7 years and have ridden it through 2 winters.  It has only been after this last winter that my front derailleur has been sticking on occasion where it's like grit has jammed in somewhere (which I'm sure it is the case).  When I'm on the fly I just knock it with my heel and it will downshift and I can push the shifter hard enough to go back up when I need to.  The first time I decided to overhaul both the front and back ones.  Took them apart, cleaned/degreased, regreased the two back cogs, and used WD-40 professional silicone on the rest of the parts as to not attract more dirt.  Then after about a month it got stuck again, and I couldn't see anything that could be jamming it (while it was still stiff as heck).  Didn't take it apart this time just used a tooth brush and silicone again and it's fine at the moment.  I'm assuming it may be that since that the roads have been grittier/dirtier from the winter with some recent rain and slush that it may just be normal.  I haven't been on the trails yet this year so I know it's not that.  Is this normal, has some kind of bur that I can't see come up and is catching grit?  EDIT:  I should also note that this is a hardtail mtb that I use for trails and winter commuting (a lot of salt and grit on the roads).
22992
my bike is:  and everything I have came with the bike, only now the axle of the rear wheel bent and the skewer has lost its grooves.  and I would like to replace the rear wheel with the 12 x 142mm version of:   I want to reuse the old casettes and disc break. I was told to buy new rotor bolts, will these do?   Will I be able to migrate all my previous parts onto this new wheel and will the wheel fit onto my bike?  update: A replacement axle would be prefered. What axle would work for my bike?
37518
A bike shop employee used a tool he said would check the wear on the chain, and said that it should be changed.   He said it took a measurement that meant the chain had expanded, but it is still hard for me understand why I should change the chain.   He said that the reason was that the expanded chain links will cause the chain rings to wear down.   That is one argument and I have no experience with it, to know if it is true.   But are there more reasons? How do I know when the chain should be changed?   My first thought is to use it until it breaks, but it probably is not the wisest option.
51061
I am currently modelling a bike based on a Norton 961:    I struggle with modelling a proper mechanical spring. It should look like this, I think:    I really don't know how to make it look flowing and natural and having enough "layers".
92221
Yesterday, I was having .  Taking the advice, I messed with the barrel adjusters.  Now, every gear is working great except the highest gear and lowest gear.  I put my bike in the highest gear and I can still click the shifter once more, but nothing happens.  When it comes time to shift down gears, I have to click the shifter once before shifting has any effect.  In the lowest gear, the chain jumps.  I have to hold down the shifter to stay in gear there.
20451
I got a flat/puncture on my bike tube, how can I fix it myself without going to the nearest bike shop? What kind of equipment would I need?
29909
My used bike came with different front and rear tires. It appears to have some kind of Kenda commuter tire in the front, and Continental Country Ride in the rear. They are both the same size (700x28).  Is this perfectly acceptable or should a bike always have matching models (and/or size)?  My main concerns from mismatching tires:   Grip thresholds may be inconsistent Ride comfort?  Wear rates (but rears seem to wear faster anyway)
29162
I just broke a spoke and this is the fourth spoke I've broken in the last 12 months.  This one was very puzzling because it came at the very end of an easy 30 mile (48 km) ride.  I was pedaling very slowly into my driveway when it snapped.   All four have been on the drive side of the rear wheel.  This is a Specialized Allez, one year old, with factory wheels.  I weigh 175 lbs (79 kg) and ride about 2000 miles (3218 km) per year.  Just recreational riding on good road surfaces.  Is this an abnormal rate of breakage?    And if it is an abnormal rate of breakage, what should I do about it?  EDIT:  I took the wheel into the LBS today. They didn't seem surprised by 4 broken spokes in a year, but everyone else is, so I'm going with everyone else. The mechanic checked the tension and they were all correct with one slight exception, so that's not the issue. The wheels are factory wheels and not exactly top flight. The spokes are 1.2 mm rather than 2 mm, so pretty thin. And they're 28 spokes per wheel, so that's cutting it even thinner from what I can gather.   Rebuilding the wheels is $125 each, so that's just not worth it. I can find much better wheels for not much more, so I'm on Amazon looking at wheels while trying not to deplete my life savings. (What some people will pay for wheels boggles the mind.)  I'll have them fix the spoke and check the tensioning so I can sell them and ride until I get replacements.   Gotta buy the tools and learn to replace spokes and true wheels....
88591
I know I should lubricate my chain regularly. I got some lube at my LBS; how should I apply it? Do I just drip some on one spot, and turn the pedals around a few times to spread it out? Drip it all over the chain? Do I clean the chain first? How can I tell if it needs lube, or if I've put enough on?
38623
Been running a set of quite nice slicks at 120-140 PSI for a couple of months. Might have done 400-600 km on the bike in that time. Tonight the rear tire exploded while the bike was sitting in my entryway. It's split right along the seam, with a roughly 2 inch long gap. Very loud bang etc.  Before I go out and buy another $70 tire, I want to get an idea of what caused this. Some possibilities that I've thought of include:   Running the tire at 140 PSI. The tire is rated to that pressure, but maybe this is still too much? Some brief stretches of gravel road (1-2km) I did on it last weekend. The bike seemed fine then however. There is a central heating/cooling vent directly adjacent to where the bike is stored. Perhaps the changes in temperature were enough to damage the tire? The roads in this area are not always very good. Maybe this is just the result of accumulated damage from dozens of minor nicks and bumps? The tire could be defective.    Edit: added a picture. Looks like the tube has a ~1cm hole in it.
54136
I'm currently trying to unlock my bike that has been sitting on my porch for a while, the key works and turns, and I can hear the lock engaging/disengaging, however I cannot get the shackle to come out. I think their might be dust/sand stuck in the mechanism however I'm not sure how to get it off now to check.
108516
I bought some road tires that were made for flat resistance, but within two months, the sidewalls on both got damaged to the point where I was getting repeated blowouts. I wrote to the manufacturer, and they were kind enough to send me a replacement pair.   In the meantime, I bought some new flat resistant tires to replace the busted ones.   Now I have two new pairs of flat resistant tires, but I only have a use for one at a time. How long can I store a new pair before I have to worry about the material degrading, dry rot, etc.?  (not mentioning the brands here because I don't want to bash the manufacturer that sent me the replacement.)
45911
Today I disassembled my current fixed-gear, and reassembled all the parts in another frame, which I am considering to purchase.  The current owner of the frame warned me that it might be too big for me, and I agree with him. Even though, I think it has good cost-benefit, so I decided to do a test-ride.  I noticed the final geometry and rideability was pretty good, and since the frame has a long headtube (which I desire) I guess the inseam problem might not be so important considering the main goal is randonneuring, where "riding" characteristics are much more important than "mounting and dismounting" characteristics. Most probably the bike will receive a drop handlebar, even though I like flat bars a lot.  Below is a photo of the current set. There are 6cm of seatpost visible, and I might want to lower an aditional 1cm. The main reason I want to somewhat stubbornly keep the frame is that I liked riding it, didn't see any major problem except for a slight touch of the upper seatstays between the thighs, but that tends to disappear since I felt the need to put the saddle a bit more forewards.  What I am asking is:     Even considering the frameset is ridiculously larger than I would   typically choose, if I like riding the bike, is there any problem that   I'm not considering, a reason NOT to keep the frameset?   I'm 1,88cm (6'3") tall, and have used 56cm bikes, this one is 64cm (seat tube, bbc to top).  Thanks for any insight!
102404
As a newbie rider, I was asked by many experienced riders and bike shop experts if I was using clipless pedals yet?  The implication was you are not really a serious rider until you are clipless, sort of a rite of passage. No one ever told me you can break bones, but told 'everyone' falls a few times, count on it, and move on.   Are there precautions or conditions where one could or should not use clipless pedal products?  The previous year, I had ridden 1700 street and paved bike trail miles on a comfort bike and a Mountain tandem with Pedal Cages and never had an issue.  I incorrectly assumed I was ready to advance.  I purchased a new touring bike with Shimano M540's.    Here is an  riding clipless.  It was an unexpected stop due to a flood closing a tame paved trail. Someone had painted a bright blue line from the trail up to where I fell ().  It was my error in trying to ride around the obstacle and ended in the railroad ballast (2"-3").  I had un-cliped going up but the M540's re-clipped  I stopped at the edge of the ballast but was clipped.  My ankle twisted > 150 degrees. It was my third ride and fall clipless. It all happened in 10-15 seconds.  I know through good friends of two very much younger but very experienced  riders who were hurt much more severely than I due to clipless.  Should I try again with the beginner clips and different pedals, or as my son and wife tell me, are you crazy?  Revisited  Having just rolled over 2,000 miles this year with flat pedals on the road I can report I have found a solid solution for me.  I now ride with "Pin" Pedals available from several manufacturers I use (Xpedo MX Force 3).  These pedals have a grid work of short pins sticking up on both sides of the flat pedals. These pins rather lock my foot on the pedal preventing foot creep or shifting out of position while allowing for quick mount and dismounting as necessary.