peggysue Posted December 3, 2009 Report Share Posted December 3, 2009 evening all....... was wondering if many people have the problem of spokes snapping under heavy preloading moves.....had 4 snap a while back,but replaced them and now 3 more have snapped. its a pain in the arse, especially having to get the freewheel off the hub to replace them. im running a dmr revolver hub , try all rim and the spokes are black sapim race spokes. they break at the hub flange everytime. i bought the wheel of a mate about 5 months ago when i started back up , and it was his mates wheel before that, but ive worked in bike shops and built many a wheel, and spoke tension is fine all round. can spokes become brittle after a couple of years? never thought about it before......or is it because i weigh like 18 stone, and they just cant take my weight lol....any help cheers Quote Link to comment Share on other sites More sharing options...
ogre Posted December 3, 2009 Report Share Posted December 3, 2009 get a new wheel from santart?! Quote Link to comment Share on other sites More sharing options...
peggysue Posted December 3, 2009 Author Report Share Posted December 3, 2009 get a new wheel from santart?!was awaiting your response matt lol,.......... gonna stick with my hub and buy a new rim and new spokes soon, but just dont want my new wheel to do the same as this is doing. you riding this weekend? Quote Link to comment Share on other sites More sharing options...
peggysue Posted December 3, 2009 Author Report Share Posted December 3, 2009 uuuuuuuuuuummmmmmmmm........minding my own business playing cod on me ps3 and bang ....went to the kitchen to find another spoke just randomly snapped itself .make that 4 spokes now wtf??? Quote Link to comment Share on other sites More sharing options...
ogre Posted December 4, 2009 Report Share Posted December 4, 2009 ever thought it might be the hub? the flanges ar prety big it might be stressing the spokes or something? that wheel had 0 abuse before you had it cause toby can't break things if he tries. phone tarty see what they have to say? doubt i'm out in lincoln till after december now cause the trains get rammed Quote Link to comment Share on other sites More sharing options...
psycholist Posted December 4, 2009 Report Share Posted December 4, 2009 Chances are the wheel wasn't stress relieved after it was built so the spokes are prematurely at the end of their fatigue life. Rebuild with new spokes and stress relieve the rebuilt wheel and it'll last for years. Lace the hub the same way as the previous spokes were laced to it for maximum fatigue life in the new build. Quote Link to comment Share on other sites More sharing options...
Ben John-Hynes Posted December 4, 2009 Report Share Posted December 4, 2009 Chances are the wheel wasn't stress relieved after it was built so the spokes are prematurely at the end of their fatigue life. Rebuild with new spokes and stress relieve the rebuilt wheel and it'll last for years. Lace the hub the same way as the previous spokes were laced to it for maximum fatigue life in the new build.What's stress relief on a wheelbuild? Quote Link to comment Share on other sites More sharing options...
Mark W Posted December 4, 2009 Report Share Posted December 4, 2009 What's stress relief on a wheelbuild?Crack.But nah, when you build the wheels some of the spokes can bind with the nipples when you tighten them, so instead of tightening them you just twist them. If you put pressure on them (various methods) you can get the spokes to 'ping' and they settle down.I had a similar issue with my wheels (Which were de-stressed) when the spokes themselves were just old. If they're shitting the bed of their own accord, might be worth trying to stop that mutiny from occurring by getting some fresh spokes. Quote Link to comment Share on other sites More sharing options...
Ali C Posted December 4, 2009 Report Share Posted December 4, 2009 Have you missed any sidehops and landed on the spokes? I have and snapped a few spokes doing other moves just from the damage of missed sidehops Quote Link to comment Share on other sites More sharing options...
psycholist Posted December 4, 2009 Report Share Posted December 4, 2009 When a wheel is newly built the spokes aren't bedded into the holes in the hub flanges. This means there are points of very high stress on the spokes as they touch only a very small area within the hub flange. This means that while the stress level overall in the wheel is very low, there are points of very high stress. Peak stress is one of the drivers of fatigue failure and a 50% reduction in peak stress increases life before failure by a factor of 10. Stress relieving is where after building the wheel you squeeze pairs of parallel spokes together with your hands as hard as you can a few times (Even using leather gloves your hands should hurt by the time you get to the last spoke pair). This overloads the spoke where it contacts the flange, deforming the flange/spoke interface so a bigger contact area exists between them. When you let that pair of spokes go the spokes will be at a much lower peak stress than they were before, but still carry the same overall tension, so the wheel will last longer before fatigue failure as well as needing less truing (The spokes gradually deform the hub at the spoke holes over time anyway, but the spoke spends longer with a very high local stress - this is why rebuilding the wheel you should keep the spoke lacing from the hub the same). The cracking and pinging in the wheel as you twist spoke nipples is not stress relieving, it's just sudden release of wind-up in the spokes as a result of part of the twist you give each spoke nipple being lost to torsion in the spoke - if the nipple threads are seized slightly this is very obvious. I get around this by overshooting the point I want the spoke nipple tightened to by about 1/8 to 1/4 of a turn and then turning the nipple back to the point I want it to be at. No pinging at all when you build wheels that way. Quote Link to comment Share on other sites More sharing options...
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