Single speed spoke snapping woes

[tinkerer]

I have been single speeding on my nice old steel commuter bike for a couple of month now. First I tried a fixed gear which was great but after about three weeks I snapped a spoke on the rear wheel. I then installed a rear wheel with singlespeed freewheel (not nearly as much fun) and lo and behold after a few weeks snapped a spoke on that.

As I am no Clydesdale (72kg) I can't imagine these spokes have been snapped by excessive weight or power so what could be the cause? For example, do single speed wheels need extra thick spokes?

Any thoughts appreciated,

Cheers,

Adam

 

[cchris2lou]

I use normal wheels , and never had that before . maybe spoke were overtensioned ?

 

[orange71]

ditto never had a problem. the bike doesn't know it's single speed - as far as it's concerned it could be just running middle ring, 4th gear. The only exception being that if you are griding up some hills there may be some torsional effect I suppose on the rear wheel?

 

[tinkerer]

I hade never broken a spoke before going single speed. The only thing I can think of is that I have to stand up whilst pedalling up a couple of hills on my route and that might I suppose increase torque levels beyond the spokes' capacity. But I only weigh about 72kg and from what I have read on Sheldon Brown's (RIP) site the torque generated by a geared MTB drivetrain on the granny ring far exceeds anything a normal single speed can produce.

 

[gump]

would think most likely just fatigue. Clearly the will then break when most load applied, like when you start to grind a hill.
Don't think ss will make it any worse - should actually help if using a dedicated hub as you can build a more even tensioned wheel.

 

[utahdog2003]

would think most likely just fatigue. Clearly the will then break when most load applied, like when you start to grind a hill.

Ditto that, I would think your breakage is from using an older wheel in a different way. If you 'seasoned' that wheel with cross country geared miles, and then started single-speed torqing up hills out of the saddle, rocking the bike with your upper body and really getting into it, then your whole bike from the frame to the bars to the wheels and cranks, is experiencing different load cycles than under geared circumstances. Not dangerous or more difficult for the components to tolerate necessarily, just different enough that the older used components are showing you their fatigue now. Relace the wheel and I bet you don't break another one, fixed gear or not.

Like driving a car for 100,000miles...if you keep it you can probably get another 50k out of your clutch. Sell it to a friend, who drives just a bit differently thatn you and bingo!...car needs a clutch! Most machines (bikes, cars, toasters, whatever) wear to the user's style, and when that style changes...

 

[tinkerer]

Yes I reckon you've hit the nail on the head as both wheels although not that old had done a season or two as geared wheels before being pressed into single speed service. I guess I'm just going to have to fork out for a specially made single speed rear wheel!

Many thanks for all the comments,

Adam