Bicycle Mechanics - Casual biker, need help.
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05-26-11, 08:25 AM
I'm from singapore and I'm a new biker, I don't know about those bicycle terms so please speak simply.. Thank you!
Firstly, it's a problem about my bicycle brakes, when i always go out for outings and rent bicycle from rental shops, their bicycle's brake is always epic, when you squeeze it, the bike stops INSTANTLY, very powerful.
However, with my new bike, when i squeeze the brakes, it always takes about 1-3 seconds to completely stop, it prefer stopping instantly. and yeah, it's a new bike so i don't think it's because of the brake being weared out. I tried approaching a local bike shop and they reluctantly replied me that there's no problem and it's already very good.. so my question is, how can i get the brakes to stop the bike instantly? do i need to adjust something or what?
Secondly, it's some brakes squeaking problems, since i got that bike, it randomly squeak when i apply the brakes, it doesn't happen all the time, only randomly (on both wet and dry days). What can I do to stop the squeaking?
Please help me with this 2 problems, thank you very much!
New bike? Step 1: Take it back to the shop you bought it from. One advantage of a new bike is you have the dealer to stand behind it (actually, to me, that is the only advantage, last new bike I bought was 1975). You pay a hefty premium for this advantage.
Squeaking brakes have a variety of causes. I think Sheldon Brown goes through several of them. Most of the time I find it is a toe in adjustment.
If you want more assistance, you really need to give more information: what bike, what type and brand brakes, what levers, etc. Too many variables.
05-26-11, 08:56 AM
i did, but the shop owner says that the brakes are perfectly fine, maybe it's made to perform like that, it's safer.. or is it a fault when the brakes takes long to stop the bike, 1-2 secs. so is there any way I can make the brake stop the bike instantly?
secondly, i've read up google about brakes squeaking, sounds too foreign for me.. toe adjustments, brake adjustments, how exactly do i do those?
anyway, thanks for your prompt reply!
05-26-11, 08:57 AM
+1 for taking the bike back to the shop.
If you want additional advice from here, you need to post what type of bike / brakes you have, if you have rim brakes or discs, the reasons for your issues will be totally different dependant on the type of brake.
05-26-11, 09:12 AM
InnovativeDan, there are many different types of brakes that can be installed on a bicycle. If you don't know what type your bike has, could you post a picture the brakes? Unfortunately each type of brake works very differently, so without knowing what you have it is almost impossible to give you advice.
05-26-11, 09:15 AM
^ read above..
as for bike type, I don't know my bike type, since i'm new to bicycles.
for brakes, I think i'm using rim brakes since the brakes are applied onto the rims of the tyres.
05-26-11, 09:24 AM
I've just taken a picture of my brakes, please take a look.
Those brakes should be able to stop really hard, if they're of half-decent quality and set up properly.
Oh, and pad compound can have a large effect too.
05-26-11, 10:33 AM
so is it a brake problem or adjustment problem?
05-26-11, 11:00 AM
I've just taken a picture of my brakes, please take a look.
Those are linear pull brakes. Shimano markets them under the brand "V-Brake."
They are likely mis-adjusted if you can't stop, but pad compound is a consideration as Kimmo said. Check your brake adjustment.
The pads should, at rest, be equidistant from the rim. If one is 1/2mm away and one is 2cm away, something is broken (could be a misaligned wheel or misadjusted brakes; but it's wrong either way). It's also possible (through some weirdness) to get them to swing oddly, having one arm move and one not; but I don't think that's normal... mine both clamp at once.
They should be close to the rim, but not touching it. Linear pull brakes require a special brake lever with more pull distance. The mechanical advantage is much higher: more pull distance, less movement on the brakes themselves, much more force applied. This means when you swing the lever an inch, the brakes do not move in an inch; however, making them travel 2mm and then applying enough travel to move them 2cm further will get you a HUGE amount of braking force without squeezing very hard at all.
In other words, the lever moves a lot, the brakes don't move a lot, and all that force over that huge distance goes into squeezing hard over that tiny distance. In any case, you don't want them to hang out extremely far from the rim. I like to keep mine very close, as close as I can get without causing mechanical problems; I also install Friction Master high-performance ceramic brakes on my car, because I find normal brakes too soft even in top maintenance condition. Adjust the barrel out about half way before you adjust your brakes, then nudge it in or out to adjust the feel of your brakes to your preference.
Kimmo is right about pad compound. Shimano makes some great pads, also Kool Stops I've been recommended but have yet to try. I've actually considered upgrading my brake pads, even though my brakes are fully functional; I like very sensitive brakes. I think I'll not get what I'm looking for in brakes until I get completely unnecessary disc brakes with copper-impregnated-ceramic pads, though.
05-26-11, 11:16 AM
I just looked closely in the bike, i found out that, when i apply the brakes (constant force), the left brake pads moves MORE than the right brake pads, the right pad is a little too close to the rim and the left is a little too far..
I tried to push the whole brake system a little to the right and press the brake again, the whole brake thing moved back into it's original position and it's doing the same again.
Can anyone help me? what do i need to adjust? any images to show?
05-26-11, 11:37 AM
Push the brake and it'll align, then squeeze and it'll return to its stable physical state.
Those brakes aren't simple. They are a complex system of springs and levers, creating a carefully balanced mesh of counter-forces that hold them into proper shape and operation. You can't just push them one way or another to make them go together right; on the up side, you can't expect them to totally foul up because you tapped on them or they drifted a bit from the wind or vibrations.
There's two screws on the sides of the brakes that seem to have no visible function. Probably very tiny, likely a slotted head with a cross cut for a small philips. Use a flat head screw driver and go very slowly; philips is more likely to grind the screw head when it slips, while flat head is more likely to slip out sideways, so I prefer flat heads.
Basically I learned by messing with them. You tighten it and it pulls the arm away, you loosen and it brings it closer. Park Tool says you tighten the one on the arm that's too close to the rim and it'll pull away, loosen the one that's farther from the rim and it'll come closer, so do that. In my case, my brakes are somehow strange, and if I tighten the left arm it pulls the right one closer or something ... honestly, I just diddle the screws a bit and watch what happens, then decide what I want to move where and make the adjustments as necessary.
http://www.parktool.com/blog/repair-help/linear-pull-brake-service-v-brake-type again. Read this.
What's happening here is when you squeeze your brake, the right pad moves in and hits your rim. It drags, but applies no braking force, just wearing the pad and the rim somewhat. Probably more the pad. The left continues to travel in until it contacts, at which point you've wasted a lot of energy bringing your left brake pad to the rim when you could have been using that to compact the pads against the wheel and force it to dissipate its momentum as heat. Now whatever travel you have left in your brake lever can be used for braking.
What you want to do is move that left brake pad in until it's exactly as far away as the right brake pad (don't get too hung up on this; it works even if they're nowhere near correct, as long as they eventually end up squeezing the rim hard enough). The barrel on the brake lever will only come out so far, so be aware! Also, those two screws only move so much!
So once you've balanced them, by some combination of moving the left one in and moving the right one out, go ahead and roll that barrel in half way or maybe 2/3 of the way in, then unbolt the bolt holding the cable to the brakes and slide it through until it's roughly okay, then tension the bolt back down so your cable stays put (important). Recheck the balance, it should be good. Roll the barrel one way or another to adjust brake tenison--out makes it tighter and pulls the pads toward the rim, in makes it looser and spaces them away.
Lots of words.
Go play with it, it will become readily apparent. It took me 20 minutes to figure it out on my own without reading anything; I looked at my brakes and started messing with things until I figured out what did what. If you totally mess it up, well. There's a bolt the cable goes to, start there. Tension it just so you can work with it, and go back to messing with the balance. You will figure it out eventually, there are only 3 things for you to mess with on the brake itself and the last (on the brake lever) is effectively another brake lever to squeeze (the barrel, all it does is pull on the brake cable).
Also Youtube will have videos of this.
05-26-11, 12:23 PM
Once you have the arms moving evenly just keep riding for a while. It takes the pads a few dozen hard stops to wear in and make full contact with the rim. If you're only a casual rider you may not have ridden the bike enough to wear in the pads yet.
After a few days of riding if they still don't stop well then you will likely be able to improve them by switching the pads over to a better quality pad. For many of us a good pad is the Koolstop salmon coloured pad. They look sort of a rusty orange colour. These pads produce more friction on the rim for the same amount of lever pull so they would likely give you the sort of performance you want.
..when i apply the brakes (constant force), the left brake pads moves MORE than the right brake pads, the right pad is a little too close to the rim and the left is a little too far..
While annoying and not very elegant, that hasn't got any effect on braking. As soon as you get enough power in the system to pinch the rim hard enough to brovide any braking the power will equalize between the sides anyhow.
But it can be adjusted, and others have already provided links/pointers on how to do that.
05-27-11, 10:32 AM
2 things, easy to do : .. weak side spring, un hook it from the top,
bend it downward ,then hook it back up, again.
many brakes have a little setscrew to adjust the individual spring tension a bit,
just bending the spring (they're kind of a soft tempered steel), Has more effect.
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