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Old 2017-09-10, 04:11 PM   #1
Canoeheadted
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Replacing spokes

So I have three spokes to replace on my KH29.

I'm guessing I have to take my crank and disc rotor off and undo several spokes to have room to slide the new ones in. Sound right?

Am I correct in thinking I could loosen the mounting screws for the disc brake, take the crank bolt out, and then use an ISIS crank remover to pull the crank/disc rotor?
I tried to remove the crank/disc and it was too tight to loosen so I chickened out.
Do I just need more torque to undo it?

I brought it to my local bike shop but I think it may be intimidating because it's been more than 2 weeks now. I'm wondering if I should get it back and try again.

I have no problem truing the wheel, I just can't get it apart/together.

Any advice?
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Old 2017-09-10, 08:13 PM   #2
RHankey
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The short/easy answer is that the disc probably has to come off to replace spokes. The longer answer, depending on the specifics of your hub/disc and the direction the replacement spokes need to be threaded, you might be able to do so without removing the disc.

Make sure the foot on the crank remover is not too large a diameter. If the foot is too big a diameter, it can push on the crank arm, at which point you risk causing damage if you force things. If the puller foot is small enough to only push on the spindle, and the puller is fully threaded onto the crank threads, then crank away.
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Old 2017-09-10, 09:29 PM   #3
davejh
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Quote:
Originally Posted by Canoeheadted View Post
So I have three spokes to replace on my KH29.

I'm guessing I have to take my crank and disc rotor off and undo several spokes to have room to slide the new ones in. Sound right?

Am I correct in thinking I could loosen the mounting screws for the disc brake, take the crank bolt out, and then use an ISIS crank remover to pull the crank/disc rotor?
I tried to remove the crank/disc and it was too tight to loosen so I chickened out.
Do I just need more torque to undo it?

I brought it to my local bike shop but I think it may be intimidating because it's been more than 2 weeks now. I'm wondering if I should get it back and try again.

I have no problem truing the wheel, I just can't get it apart/together.

Any advice?
If you need to replace 3 spokes, you may need to replace the whole lot. When you ride with broken spokes, the extra forces applied to spokes near the broken ones can start to damage them. This can cause more spokes to fail. I would replace the 3 but if any other spokes fail, the wheel needs a full set of new spokes.

When replacing the broken spokes, you will not need to take any other spokes out. You can flex spokes quite a bit to work them into the pattern.

In terms of removing the crank and rotor, you will have to do it. Unscrew the calliper from the standoff first to free up the rotor (do not pull the brake lever while the disc is not present - bad things can happen!) and use a long handled 8mm key to get the bolt out. This bolt will be done up very tight. Then use an extractor to take the crank off. When you put the crank bolt back on, don't be afraid to use a lot of force. The bolt will likely need a quick tightness check after a couple of rides and then after a week or two to make sure it was tight enough and has not loosened.
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Old 2017-09-11, 11:52 PM   #4
jtrops
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It is true that when I see multiple spokes breaking it sends up a red flag about the rest of them.

I would just add that the reason spokes break in multiples is either because of uneven tension that causes the metal to fatigue due to flexing back and forth at the elbow, or because of some kind of trauma. If they are broken due to poor tension it may be worth it to try to replace the broken ones, but it is more likely that you have the first problem, and a new set of spokes would fix it.

If it is because of trauma to the spokes the broken spokes should show some evidence like abrasion, bending, or similar. In that case you probably haven't ridden much after the spokes broke, and haven't put the other spokes through much of a fatigue cycle. It is also possible that the spokes broke somewhere along the length of the spoke in this case (possible, but not necessary). So, in this case replacing the spokes could be a lasting repair.
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Old 2017-09-12, 04:40 AM   #5
Canoeheadted
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So I picked up the uni from the shop and took another crack at it. (it still wasn't done )

Sure enough, with a little more torque, the crank slowly started pulling off.
Everything went perfect from then on.

An hour later the spokes are replaced and the wheel is damn near perfectly trued. The spokes all seem to have even tension.
So I'll take 'er for a ride tomorrow and see if anything settles or moves.
I'll keep a close eye out for more spokes breaking during the ride.

I'm guessing I saved two hours in the shop so I'm gonna pay myself with a new pair of 125 Nimbus cranks for my backup 29'er!
Gotta go... wife's coming!
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Old 2017-09-13, 07:36 AM   #6
unibokk
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Make sure to pre stress the new spokes.
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Old 2017-09-13, 02:51 PM   #7
Canoeheadted
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How would you go about doing that?

I've ridden twice since and will go through the wheel tonight and touch up anything that needs it.

Thanks in advance.
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Old 2017-09-13, 04:44 PM   #8
unibokk
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Just grip the spokes with your hand and squeeze them together.

Or you could overtighten them a half turn and then bring them back to true, according to BungeeJoe

Last edited by unibokk; 2017-09-13 at 04:45 PM.
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Old 2017-09-13, 08:33 PM   #9
lightbulbjim
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Good howto on spoke stressing (and general wheel building): https://sheldonbrown.com/wheelbuild.html#seating
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