Pad coming short of rim
#1
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Pad coming short of rim

I'm working on a donated bmx bike that is to be (re)donated to an organization when I get it fixed. When I got it, the brakes were in bad shape with some bent calipers, and bad cables. I got the cables sorted and bent the calipers back to where I thought they should be. I have an issue that I can't lower the pads enough on the front calipers to hit the rim. I am assuming that these were original to the bike so I feel that I must be missing something. As a reference, the rears have plenty of room to move both up and down to hit the rim. Any suggestions?

#2
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That's the story of big-box bikes. Sometimes the components are spec'ed without checking to see if they'll actually fit or work on the frame they're attached to. I've struggled with them. First, buy some new pads. These look rock hard and probably wouldn't stop a roller skate. Second, see if the caliper is centered. By that I mean, when you squeeze the lever, the pads should hit the rim at the same time. Sometimes a pad falls short because the one on the other side drops long, and centering can even them out. Third, square the pads. This one isn't parallel to the arc of the rim. Fix that. It will put more pad in contact with the rim and less in contact with the sidewall of the tire. Last, if both pads still fall short, remove them and enlarge with a rat-tail file the bottom of the loops that they bolt in to. But not too thin, you don't want them to break.
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The fork looks like it was installed backwards. Turn it around so the dropouts are facing forward, then re-install the brake.
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Here is a video that may help you
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JoeTBM (The Bike Man) - I'm a black & white type of guy, the only gray in my life is the hair on my head
www.TheBikeMenOfFlaglerCounty.com
JoeTBM (The Bike Man) - I'm a black & white type of guy, the only gray in my life is the hair on my head
Last edited by JoeTBM; 10-10-22 at 04:24 PM.
#6
Really Old Senior Member
I suggest you give the bike a good braking test before you pass it on to someone.
Those calipers can be extremely flexy when "undamaged".
Now that they've been bent once?, they may be "compromised" to the point where they may want to bend again on a panic stop.
Those calipers can be extremely flexy when "undamaged".
Now that they've been bent once?, they may be "compromised" to the point where they may want to bend again on a panic stop.
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These steel calipers are no Universal or Barilla ones what with their crack prone aluminum arms. Really these steel arms are rather strong in the sense of rarely ever having a failure due to stress cracks and such. Do they flex in the direction or the rim's rotation, yes. Are they sometimes hard to keep centered (due to a poor spring/center bolt fitting), Yes. But do we see broken arms after the front wheel/fork/bars swing way around and the cable adjuster arm gets badly bent from the down tube, no. Andy (who has straightened and toed in hundreds of these and other steel side pull calipers with no memory of a failure)
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Maybe some more pics would be helpful. A view from the side a little further back so we can see how the fork is aligned with the headtube. And also a better pick of the wheel showing the rim and it's brake surface.
When I first looked at the pic, I thought your shoes were well below the brake surface. But on closer inspection, I guess that's the sidewall of the tire. The weird little pattern by the tread I thought were witness lines which typically just hit above the rim so you can see that your tire is in the bead seat properly. However I guess they aren't. But I am still sort of puzzled as to what I am seeing. Where is the rim?
Also, is it possible this isn't the wheel size that is suppose to be on the bike and some previous owner replaced the original wheels with the wrong size and just made do? Knowing the model and brand of bike, maybe someone can find what size wheel it was spec'd with.
When I first looked at the pic, I thought your shoes were well below the brake surface. But on closer inspection, I guess that's the sidewall of the tire. The weird little pattern by the tread I thought were witness lines which typically just hit above the rim so you can see that your tire is in the bead seat properly. However I guess they aren't. But I am still sort of puzzled as to what I am seeing. Where is the rim?
Also, is it possible this isn't the wheel size that is suppose to be on the bike and some previous owner replaced the original wheels with the wrong size and just made do? Knowing the model and brand of bike, maybe someone can find what size wheel it was spec'd with.
Last edited by Iride01; 10-11-22 at 08:35 AM.
#9
Really Old Senior Member
These steel calipers are no Universal or Barilla ones what with their crack prone aluminum arms. Really these steel arms are rather strong in the sense of rarely ever having a failure due to stress cracks and such. Do they flex in the direction or the rim's rotation, yes. Are they sometimes hard to keep centered (due to a poor spring/center bolt fitting), Yes. But do we see broken arms after the front wheel/fork/bars swing way around and the cable adjuster arm gets badly bent from the down tube, no. Andy (who has straightened and toed in hundreds of these and other steel side pull calipers with no memory of a failure)
I've dealt with this type on Huffy's where you would end up bottoming the lever against the bar because of flex.
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I guess sometimes I write a little cryptically. I knew where the rim was. I just couldn't see it as well as I would have liked. Perhaps I should have just said make a better picture that shows more of the rim!
I entirely missed the fork ends pointed the wrong way! So thanks for going to the trouble. Now I don't even feel we need new pics from the OP.
I entirely missed the fork ends pointed the wrong way! So thanks for going to the trouble. Now I don't even feel we need new pics from the OP.
#12
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I turned the forks around and it cured the brake issue, put new pads on, adjusted, and centered. Someone had previously spun the handlebar stem 180 degrees, which threw me off. I put it back and everything is
. Thanks to all!

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