The above is the result of a Dicta 22T BMX Freewheel adapted to a chainring carrier used in a serial-driven freewheel crank setup.
Freewheel was in service for only ~600klm (370miles) before seizing. It seized without warning, feet lost contact with the pedals, one pedal spinning over smacked my leg in the calf muscle, the pedals grip-providing grub screws gouging tears in it, the whole situation nearly threw me off the bike at ~40kph.
170mm freewheel cranks were used. Rider weight ~70kg (154lbs). Max possible static torque applied when standing on a single horizontal crank arm is therefore ~117Nm (86ft-lbs)of torque. Was mostly moderate assist pedaling only. Max shock loading can only be guessed at. however shock loading due to jumping on a crank arm was minimised though care.
I don't know what sort of steel is used in the freewheel's outer tooth/ratchet ring, but it is definitely case hardened and pretty resistant to a Dremel cutoff wheel which i later used to cut into it as a test of hardness. There are parting fractures in the valleys of every ratchet tooth (stress riser points), and eventually several have obviously sheared right off. Part of one ratchet tooth even compression welded itself to the inner driver ring which is what eventually caused final seizure. I'm still surprised at the lack of warning noises/intermittent lockup before complete failure.
Why didn't/don't i use a sickbikeparts/ENO freewheel instead of a cheap-ass Dicta freewheel i hear you ask?......Because i need a freewheel with dual row support bearings to take the angular loading applied by offset mounted chainrings. This is a necessity during non-pedal assist power transfer when power is being passed though the chainring set in a freewheeling state (when unlocked ratchets/pawls offer no structural rigidity). The Better quality freewheels like the sickbikeparts/ENO use a single row cartridge bearing and therefore are unusable in my setup as a single bearing offers negligable angular force support.
So take warning ye all. Especially owners of standard cyclone freewheels (they are also made by Dicta
). Generally though, i think freewheels just aren't designed for the levels of torque applied at the crank which are usually 2>5 times greater than at the rear wheel where they are supposed to be mounted. Sure Trials bikes use 18T freewheels, but they are geared so low for fast acceleration that i doubt the rider can develop the same loading as when these same freewheels are adapted to large chainrings that allow much taller gearing (higher loading).Who else has this happened too????? There must be others out there?
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. Originally the lockring did unscrew almost immediately (even when torqued significantly). I quickly fixed that with locktite and never had the same problem again (I actually had to cut the lock ring out with a Dremel just to open it up after it failed)
). The drag is the worst of any freewheel I have hand spun. It's also noisy as hell compared to other freewheels, even when packed with grease to try and quiet it down.
