Slipping exercise bike freewheel
 

3 year old Schwinn 113 exercise bike, ridden about 60 miles/week. Has a
belt driven flywheel with an eddy current resistance mechanism. Recently,
the peddles have begun to briefly lose resistance. I had thought the belt
was slipping, which is what it feels like when you're riding, but after
taking the cover off, I see this is not the case; the belt & its tensioner
are fine. The freewheel mechanism is slipping. Rather than having a
ratcheting pawl mechanism like a derailer street bike, the freewheel
mechanism consists of a smooth shaft on the end on the pulley, which rides
in the middle of the flywheel on what appears to be a roller bearing, but
one which will only rotate in one direction. For support, the axle and the
pulley shaft actually ride on regular sealed ball bearings at each end, this
middle roller section appears to only provide the freewheel action. Has
anyone seen this type of unit/failure, and is there a way to repair it w/o
replacing the flywheel, which would likely cost more than the bike's worth?
I have no idea what parts availability would be for this thing. Since it's
not a street bike, I can probably live w/o the freewheel action, and will
likely rig up a way of just locking the pulley to the flywheel if a repair
isn't reasonably doable.

TIA

Dan

Slipping exercise bike freewheel
 

On Fri, 4 Apr 2008 16:04:18 -0700, "Dan" may have
said:

3 year old Schwinn 113 exercise bike, ridden about 60 miles/week. Has a
belt driven flywheel with an eddy current resistance mechanism. Recently,
the peddles have begun to briefly lose resistance. I had thought the belt
was slipping, which is what it feels like when you're riding, but after
taking the cover off, I see this is not the case; the belt & its tensioner
are fine. The freewheel mechanism is slipping. Rather than having a
ratcheting pawl mechanism like a derailer street bike, the freewheel
mechanism consists of a smooth shaft on the end on the pulley, which rides
in the middle of the flywheel on what appears to be a roller bearing, but
one which will only rotate in one direction. For support, the axle and the
pulley shaft actually ride on regular sealed ball bearings at each end, this
middle roller section appears to only provide the freewheel action. Has
anyone seen this type of unit/failure, and is there a way to repair it w/o
replacing the flywheel, which would likely cost more than the bike's worth?
I have no idea what parts availability would be for this thing. Since it's
not a street bike, I can probably live w/o the freewheel action, and will
likely rig up a way of just locking the pulley to the flywheel if a repair
isn't reasonably doable.

It's probably a roller one-way clutch. Those can be vulnerable to
buildup of crud on the ramps; I'd try cleaning it and closely
inspecting it for flat spots in the rollers, weak springs (there could
be a folded flat spring behind each roller) and/or worn spots on the
ramps and center collar. If there's no lube on it now, leave it dry;
if there's a thin film of something oily, I would use old-style Ford
ATF. (It's much less slippery than Dexron.)

This type of clutch is common in automatic transmissions for cars and
trucks.

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Slipping exercise bike freewheel
 

"Werehatrack" wrote in message
...

It's probably a roller one-way clutch...

Thanks for the reply. I've worked on a lot of machinery, but this device is
a new one on me. Reading about them a bit, I think it may actually be
slipping where it's pressed into the flywheel. That's what it feels like &
if I "torque it" just the right way with, it makes a little dry screech
sound that seems more like the union between the bearing & the flywheel than
the lubricated surfaces where the pulley shaft meets the bearing. I may be
able to loctite it in there. In the mean time, I filed a flat on one spot
on the edge of the pulley where is sits next to the flywheel &
drilled/tapped a hole in the flywheel for a 1/4 20 cap screw, one side of
which sits next to the flat on the pulley & keeps it from turning. So no
freewheel action but at least I can use the bike!

Thanks for the tip!

Dan