How strong are light weight cranks?

[Kayrehn]

Was contemplating getting lightweight boutique cranks like THM clavicula stuff when I read the Storck powerarms user manual that says it is recommended that the cranks are sent back after 3 years to the dealer for a checkup in case the thing breaks down etc. So are such cranks (with weight limits to them) necessarily disposable after a number of years? I do feel that more mainstream carbon cranks like Sram and Campagnolo ones should be more lasting though, given that they don't come with weight limit or similar precautionary note, from what I know at least...

[HillRPete]

Well there's strength as in stiffness which is fairly well documented in the FWB Crank Tests, and strength as in durability, which is hard to measure, because every rider uses and treats the gear differently.

[NiFTY]

Any material can fatigue, be it carbon or otherwise. I am sure the 3 year service is a very conservative estimate.

[sugarkane]

Not all lightweight cranks are equal...

THM recommend for their m3 cranks that you send em back for a refurb every 10 years or 100000kms

[ras11]

Aren't Storck cranks not also made by THM?!

[Juanmoretime]

This is season number 6 for my VumaQuads. I have changed rings and bottom brackets every other year. They did not wear out it was more of predictive maintenance. I don't like mechanicals on the road so I project out when to replace something. This will be my last season on these cranks since I think 6 years is enough for a lightweight part that takes the stress that cranks take.

[jmartpr]

THM is the manufacturer of Storck PowerArms...they are basically the M3 model.

[latman]

Carbon (w/epoxy resin) has no fatigue life and does not deteriorate with time , its weakness is the bonding to the threaded metal parts which can be affected a lot by temperatures especially due to expansion/contraction of Aluminuim inserts

[HillRPete]

THM is the manufacturer of Storck PowerArms...they are basically the M3 model.

Huh? M3 has a replaceable spider, whereas Power Arms don't.

Edit: good to know, thanks jmart.

[jmartpr]

Yes...that's basically the difference but the 30 mm alloy axle, arms and design is the same. They even use THM BBs which are sent on THM packaging. Storck contracts THM for various components like forks and cranksets.

[Geoff]

SiSL are pretty light. They are also beefy as heck.