Spoke breakage warning NuVinci

[SirJakesus]

Mods, sorry for double posting this in two places but I feel it needs to be seen. You can move this to the rack mount forums after its had some exposure if you wish.

For any members who have purchased a NuVinci chain drive kit from Staton inc. check out your rear wheel. Mine came with incorrect nipples that made kinks in the spokes where they were screwed to the rim. I believe this eventually led to stress and breakage at the threaded spoke ends and I would advise you to keep a careful eye on the supplied rear wheel. I noticed 3 broken spokes after 450miles on the bike. The rim luckily was high enough quality that it never lost its true and I only discovered the snapped spokes by chance.
If you are thinking of ordering one of these kits be warned. I emailed David to let him know of the fault in his product but I doubt I'll get a response or any compensation. Hopefully he rectifies this issue before he ships any more of these kits. If you're going to order one ask him directly before you order if the spokes are attached to the rims straight with no kink. I would personally refuse the purchase if this is the case unless you don't mind paying again for the components or service to rebuild the wheel correctly.
Please check out this page of my build thread in the picture gallery to see what I'm talking about and for more information on this subject.

http://www.motoredbikes.com/showthread.php?t=9041&page=7

 

[Tylden]

Thank you !

Thanks for the heads up. I ordered my kit and new wheel with the NuVinci hub last week. I'll be sure to call and ask about this if my wheel hasn't been shipped yet. If it has, I'll make sure mine doesn't have this feature before I build up the bike. I'm glad you discovered it after you made it home safely. Things could have been much worse.

 

[Warner]

Am I safe in assuming this issue only affects the kits with the NuVinci hubs? I'm also assuming it's related to not being able to source the correct length of spokes for a proper fit?

Thanks in advance,

Warner




PS - My Staton kit is on the way...hopefully will arrive tomorrow so I can spend some time working on it this weekend! I did NOT order the NuVinci hub with mine...just the regular outside-drive chain kit with a 17 tooth sprocket for higher cruise speeds.

 

[SirJakesus]

Warner, their other kits use a normal sized double freewheel that you either lace to your current rim or you order their complete wheel. In either case the spokes should attach to the rim at a normal straight shot but since the nuvinci hub is so large you have to use nipples that allow the whole spoke to stay straight which staton did not. The nipples staton used are installed perpendicular to the rim and the spoke has to kink at the very end to then be attached to the oversize hub. This creates a stress point. Using DT swiss spokes and nipples I found they didn't rest in the rim perpendicular but rather were in line with the spoke effectively transferring the stress to the rim rather than one spot on the spoke. If you check out my pictures in my picture gallery thread or even the pics on statons site look closely where the spokes meet the rims. You can see they come off the hub at an extreme angle and then bend into the nipples which are completely straight to the rim. I'd be very surprised if I was the only person having problems with one of these pre-built wheels.
Just keep checking yours if you have one. Losing stability in the rear wheel at speed can be very dangerous to you and those you're riding around.

 

[Warner]

Warner, their other kits use a normal sized double freewheel that you either lace to your current rim or you order their complete wheel. In either case the spokes should attach to the rim at a normal straight shot but since the nuvinci hub is so large you have to use nipples that allow the whole spoke to stay straight which staton did not. The nipples staton used are installed perpendicular to the rim and the spoke has to kink at the very end to then be attached to the oversize hub. This creates a stress point. Using DT swiss spokes and nipples I found they didn't rest in the rim perpendicular but rather were in line with the spoke effectively transferring the stress to the rim rather than one spot on the spoke. If you check out my pictures in my picture gallery thread or even the pics on statons site look closely where the spokes meet the rims. You can see they come off the hub at an extreme angle and then bend into the nipples which are completely straight to the rim. I'd be very surprised if I was the only person having problems with one of these pre-built wheels.
Just keep checking yours if you have one. Losing stability in the rear wheel at speed can be very dangerous to you and those you're riding around.

Thanks. I figured it had to do with the large size of the NuVinci hub. I DID order a wheel from them since I'll be running such a narrow tire (1.25") - I ordered the 48 spoke wheel. I'd also wonder if the issue is accelerated (so to speak!) because of the tremendous amount of torque the engine is able to put on the hub with the lower gearing of the NuVinci setup. I remember reading that if someone stood in front of the bike and held the handlebars, the bike would move them out of the way. To put that much torque on a bicycle rim from a stop seems like it would put a LOT of stress on all the drive components, no?

Warner


PS - The way mine is coming geared, I'll have to pedal up to 10mph or so before I even use any "assist". Hopefully this will put less stress on everything, except my legs, which I WANT to put some stress on. Part of how I rationalized this kit was that I would get some exercise out of it! Haha!


PPS - I just went and looked at your build pictures and I see EXACTLY what you are talking about! Yeah, that definitely looks prone to failure the way those spokes come out of the rim!

 

[Tylden]

SirJakesus, private message sent.

 

[duivendyk]

The stress on the spokes only occurs if you do a jack rabbit start in low gear,or go up a steep hill at WOT.But the stress concentration at the kink in the spoke will accellerate fatigue fracture of the spoke due to torsional vibration in the drive train.What surprises me is that Staton Inc did not catch the problem.You should be able to fix it by reaming out the rim so that the nipple can come out at an angle,(slow work 36 spokes to work on) or lace the wheel differently.