Originally Posted by
simplyserving .
As I went to the shop to hear exactly what needed to be replaced / corrected I was a bit overwhelmed. I had spent the week trying to educate myself so that I was prepared but I guess I concentrated on the wrong areas. I was so taken back by the scratches I had found later, that I was assuming it would be something structural with the frame. As many if you had commented, the frame is fine despite the scratches. I cannot remember the exact terminology or exactly everything mentioned, but the major parts needing to be replaced (at least cost wise) were the Truvitav (i think he said) double crankset, the chain, and the brake pads. The wheels had some minor denying but he said they would be good for a while. I did not realize it, but there were 2 different tires on the bike. I take it the front tire must have worn out because that was the newer of the two. He said as part of the tune-up, he would swap the two tires and put the better of the two in the back. He too felt it was a nice bike, but it needed some work to be good.
My questions are this. One, how do you know when you need a new chain? I could see where it was hitting against the front derailler and it appeared to be a bit rusty (or extremely dirty). Two, in regards to the crankset, what do I look for there? It too appeared rusty or dirty (the sprocket parts) and some of the teeth appeared slightly bent or worn. Could this and not the chain be causing the rub? Lastly, brakepads. How do I know which ones to order? Are they specific or sized?
My last question is should I take the bike for a "second opinion" or are these relatively normal components to go on a bike? I have the bike and took some pictures if that helps. If you can tell by looking at a photo (or can give an opinion) email me at
[email protected] and I will send you the photos. One last one, will the tires be an issue?
The easiest and most reliable way to measure chain wear is to use a ruler to measure the length of 12 links, and if that length is greater than 12 1/8", the chain is shot. Also note that a "link" is actually two pieces: a piece whose side plate is the most external and is the plate against which the link pin is pressed; a piece that follows the previously link and whose side plate sits just inside the previous link's side plate. Also, it's best to a machinist's rule, but you can get buy on a regular ruler.
What is wrong with the crank? It would be a surprise if the crank arms themselves were bad. It's not of the question, but there other things used with the crank that go bad first (excepting in the case of an accident, I guess)
- Chainrings: these will wear more quickly if the chain has worn too much. Also, some of the big chainring's teeth can look different. Special tooth shapes are used on some chainrings to speed pick-up of the chain when shifting to the large chainring. Of course, chainring teeth can get bent.
- Bottom bracket: this is the bearing assembly, and depending on the type of crank set, the bottom bracket axle (upon which the cranks rotate). Some crank--newer cranks--have an integral axle, so in that case, the bottom bracket assembly is just made up of bearings and bearing cups. No matter the case, bottom bracket bearings do need to be replaced from time to time, as is the case with all bearings.
Tires: there's no functional reason that the front tire has to match the back tire. I have at times had on the rear a different brand and/or color tire than on the front. There are a very small number of tires which are different and are "supposed" to be paired together. The only ones I can think of are the Continental Attack & Force tires. The Attack is supposed to be used on the front in combination with the Force on the back, but the reality is that you can use 'em however you like, including separately.
Brake pads: it's a good idea when buying a used bike to replace the brake pads anyway. Over time, brake pads can grow hard, especially if they're not used for an extended period of time. Brake pads also wear quickly, a bit less fast than tires (unless you do a lot of fast descents of mountains, through tight corners). There are generally two types of replaceable brake pads for road bikes with cantilever brakes: Shimano compatible and Campagnolo compatible. A bike shop can tell you which you need, or you can just tell us what brand brake calipers you have so that we can let you know what type you need. Generally, when the grooves are gone on the brake pads, it's time to replace them. Some brake pads have wear indicators on the sides.
Derailleurs: if the chain is rubbing the front derailleur cage, almost every time that can be fixed just by proper adjustment of that derailleur.
The wheels: it's not uncommon for wheels to get dents from rocks on the road. It's difficult to say much more without seeing your wheels.
The frame: you saw, and you likely saw some of the scratches. That's not too much of a concern. It's mostly an aesthetic issue. A dented (depending on the location and size of any dents) or cracked frame would be a concern.
Things that wear and have to be replaced are the following:
- Chain
- Tires
- Inner tubes
- Handlebar tape
- Cables and cable housing
- Brake pads
- Bearings (the least frequent of all of these)
Of course eventually everything breaks down, but the six things I listed are the ones that go most quickly. How quickly they go depends on how well you care for your bike and clean it, how you ride and how heavy you are, the area in which you ride (road conditions, road detritus that can puncture tires and inner tubes), and the weather where you ride (rain, heat, ...). Obviously, the person riding their bike 10,000 miles per year is going to have things wear out more quickly than someone who rides their bike 500 miles per year.
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