Rear Spokes Breaking Rear 700c Giant Commuter
06-04-16, 12:26 AM
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Rear Spokes Breaking Rear 700c Giant Commuter
Hi all, this is a question about my brothers bike - a 5yo 8sp Giant Commuter with 36h 700c wheels laced over two and under one.
Recently he started breaking spokes on the rear wheel.
The LBS replaced the rear with DT DB.
Problem is he's having the same issue after the fix.
The bike is ridden 60-80km per week approx and he weighs 85kg.
He has been riding for over 40years and not particularly hard on his bikes watching out for potholes etc within reason.
The spokes are breaking at the hub (LF alloy).
Couldn't tell you if the alloy rims are box section or not or eyeleted.
The LBS's plan is to rebuild the wheel with shorter spokes laced over one and under one or with shorter spokes again in a radial pattern.
My thoughts would be:
• Lace the wheel over three and under one to allow more flex before shearing.
• Use straight / thicker gauge spokes as these would have slightly more strength.
But I'm no expert.
Any suggestions or advice welcome thanks.
Recently he started breaking spokes on the rear wheel.
The LBS replaced the rear with DT DB.
Problem is he's having the same issue after the fix.
The bike is ridden 60-80km per week approx and he weighs 85kg.
He has been riding for over 40years and not particularly hard on his bikes watching out for potholes etc within reason.
The spokes are breaking at the hub (LF alloy).
Couldn't tell you if the alloy rims are box section or not or eyeleted.
The LBS's plan is to rebuild the wheel with shorter spokes laced over one and under one or with shorter spokes again in a radial pattern.
My thoughts would be:
• Lace the wheel over three and under one to allow more flex before shearing.
• Use straight / thicker gauge spokes as these would have slightly more strength.
But I'm no expert.
Any suggestions or advice welcome thanks.
06-04-16, 01:37 AM
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Radial, 2 cross and straight gage spokes all make a stiffer and more brittle wheel. Butted spokes distribute loads more evenly. Radial lacing on the wrong hub can break the flange of the hub, especially if it is not forged. It is hard to beat standard 3 cross lacing with double butted spokes.
Three possibilities. One is the holes in the BMX style hub are a bit crude, or the flange too thin, and may be stressing the spoke heads. Another is if the spokes are not properly stress relieved. Third is if the spokes are not tight enough. I would be tempted to upgrade the hub.
Three possibilities. One is the holes in the BMX style hub are a bit crude, or the flange too thin, and may be stressing the spoke heads. Another is if the spokes are not properly stress relieved. Third is if the spokes are not tight enough. I would be tempted to upgrade the hub.
06-04-16, 05:54 AM
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Look at it this way:
36 spokes cross 3 should yield a relatively stout conventional wheel. There are lots and lots of those around that don't have a spoke breaking problem.
A bicycle wheel only has 4 components: hub, spokes, rim and build quality. My bet is the build quality isn't up to snuff. If that's the case, having the same guy do something goofy to the wheel isn't going to solve the problem.
36 spokes cross 3 should yield a relatively stout conventional wheel. There are lots and lots of those around that don't have a spoke breaking problem.
A bicycle wheel only has 4 components: hub, spokes, rim and build quality. My bet is the build quality isn't up to snuff. If that's the case, having the same guy do something goofy to the wheel isn't going to solve the problem.
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06-05-16, 04:25 AM
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Interesting thoughts about the hub flange and build quality. Will leave the LBS to their own devices as they are doing it under warranty but sounds like they possibly don't know what they're doing. I have an old 8 sp mavic rimmed wheel that should fit as a test mule.
06-05-16, 07:39 AM
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A wheel with all the spokes at matched tension acts like a Whole,
spokes that are let be loose are worked in compression/tension cycles, as individuals
and metal fatigue from that, is what typically breaks spokes..
spokes that are let be loose are worked in compression/tension cycles, as individuals
and metal fatigue from that, is what typically breaks spokes..
06-05-16, 09:35 AM
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If the shop is suggesting building the wheel entirely radially, that's not smart from a durability standpoint. It works okay for very small (16" or less) wheels.
If, however, they are suggesting half-radial (the left side radial, right side crossed), that often results in a stronger wheel, with more even bracing angles.
It is unclear from your post exactly what the shop is suggesting... But at any rate, traditionally built wheels are fine, for the most part, and unless they're building you a wheel for free, there's no way that it'll be cheaper than a machine built new one. Even(ish) spoke tension and close bracing angles are going to do way more than changing the spoking pattern.
Regardless of whether the wheel is being built by them, a distributor, or a distributor's machine, the wheel should be evaluated for even tension before leaving...
If, however, they are suggesting half-radial (the left side radial, right side crossed), that often results in a stronger wheel, with more even bracing angles.
It is unclear from your post exactly what the shop is suggesting... But at any rate, traditionally built wheels are fine, for the most part, and unless they're building you a wheel for free, there's no way that it'll be cheaper than a machine built new one. Even(ish) spoke tension and close bracing angles are going to do way more than changing the spoking pattern.
Regardless of whether the wheel is being built by them, a distributor, or a distributor's machine, the wheel should be evaluated for even tension before leaving...
06-06-16, 05:31 PM
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If the shop is suggesting building the wheel entirely radially, that's not smart from a durability standpoint. It works okay for very small (16" or less) wheels.
If, however, they are suggesting half-radial (the left side radial, right side crossed), that often results in a stronger wheel, with more even bracing angles.
It is unclear from your post exactly what the shop is suggesting... But at any rate, traditionally built wheels are fine, for the most part, and unless they're building you a wheel for free, there's no way that it'll be cheaper than a machine built new one. Even(ish) spoke tension and close bracing angles are going to do way more than changing the spoking pattern.
Regardless of whether the wheel is being built by them, a distributor, or a distributor's machine, the wheel should be evaluated for even tension before leaving...
If, however, they are suggesting half-radial (the left side radial, right side crossed), that often results in a stronger wheel, with more even bracing angles.
It is unclear from your post exactly what the shop is suggesting... But at any rate, traditionally built wheels are fine, for the most part, and unless they're building you a wheel for free, there's no way that it'll be cheaper than a machine built new one. Even(ish) spoke tension and close bracing angles are going to do way more than changing the spoking pattern.
Regardless of whether the wheel is being built by them, a distributor, or a distributor's machine, the wheel should be evaluated for even tension before leaving...
