Problem with FSA gossamer mega exo left crank arm

Quoted message said:

I'm posting my experience crankset because I haven't seen much
discussion about the reliability of this design.

For those not familiar, this crankset employs a hollow bottom bracket
spindle which is fixed to the right crank arm. The left side of the
spindle is splined, and not tapered. The left crank arm slides over
the splines and is held in place by two pinch bolts. BB bearings are
installed external to the BB shell. Bearing preload is achieved
with a bolt that threads into the hollow axle, shouldering against the
left crank, and pulls the whole assembly together. This design
appears to be very much like Shimano's modern cranks, although I have
not looked closely at the Shimano version.

I've had this crank on my cyclocross bike for about 3 months.
I've put maybe 1000 km on road, and perhaps 12 hrs of off road,
including a fair amount of steep uphill climbs. I weigh about 200 lb.

I found that in use, the preload bolt would gradually loosen, and the
left arm would walk off of the splines, even though the pinch bolts
were tight. As a result I began to ensure that the crank was
properly seated before each ride. With continued use, the splined
crank/spindle interface began to creak when pedaling out of the saddle.
As of now, the crank is still useable, but I can forcefully rock the
crank arm back and forth on the splines, with the pinch bolts tight.
I can't imagine this will last more than a few hundred km more before
failure.

I wonder if anyone has had similar experiences with this or other
cranks of this basic design?

I have the same issue. I use it on my rain bike and do sprint workouts
on it. I've noticed it coming loose a couple times. I made sure I had
proper torque as well on the pinch bolts...

Andrew F Martin said:

Quoted message said:

I'm posting my experience crankset because I haven't seen much
discussion about the reliability of this design.

For those not familiar, this crankset employs a hollow bottom bracket
spindle which is fixed to the right crank arm. The left side of the
spindle is splined, and not tapered. The left crank arm slides over
the splines and is held in place by two pinch bolts. BB bearings are
installed external to the BB shell. Bearing preload is achieved
with a bolt that threads into the hollow axle, shouldering against the
left crank, and pulls the whole assembly together. This design
appears to be very much like Shimano's modern cranks, although I have
not looked closely at the Shimano version.

I've had this crank on my cyclocross bike for about 3 months.
I've put maybe 1000 km on road, and perhaps 12 hrs of off road,
including a fair amount of steep uphill climbs. I weigh about 200 lb.

I found that in use, the preload bolt would gradually loosen, and the
left arm would walk off of the splines, even though the pinch bolts
were tight. As a result I began to ensure that the crank was
properly seated before each ride. With continued use, the splined
crank/spindle interface began to creak when pedaling out of the saddle.
As of now, the crank is still useable, but I can forcefully rock the
crank arm back and forth on the splines, with the pinch bolts tight.
I can't imagine this will last more than a few hundred km more before
failure.

I wonder if anyone has had similar experiences with this or other
cranks of this basic design?

I have the same issue. I use it on my rain bike and do sprint workouts
on it. I've noticed it coming loose a couple times. I made sure I had
proper torque as well on the pinch bolts...

IMO, it's a design defect. Last fall, I saw two of these FSAs with the
same problem on a charity ride. One bike (a Giant, IIRC) was <1000mi
new , but the other, an Orbea, had been back to the LBS several times,
according to the owner. The problem kept recurring.

[email hidden] says...

Quoted message said:

I wonder if anyone has had similar experiences with this or other
cranks of this basic design?

You could try Loctite on the preload bolt.

Barnard Frederick said:

[email hidden] says...

Quoted message said:

I wonder if anyone has had similar experiences with this or other
cranks of this basic design?

You could try Loctite on the preload bolt.

Should I really be relying on my preload bolt to keep my cranks in
place? I doubt locktite would be able to counteract the forces of
sprinting on those cranks...

Quoted message said:

IMO, it's a design defect. Last fall, I saw two of these FSAs with the
same problem on a charity ride. One bike (a Giant, IIRC) was <1000mi
new , but the other, an Orbea, had been back to the LBS several times,
according to the owner. The problem kept recurring.

Is the FSA design significantly different from the Shimano version? I
haven't seen any complaints about the shimano cranks yet, and I assume
there are more people using them.

Anyway, I'm going back to square taper-just ordered a campy centaur
compact & BB.

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I'm posting my experience crankset because I haven't seen much
discussion about the reliability of this design.

For those not familiar, this crankset employs a hollow bottom bracket
spindle which is fixed to the right crank arm. The left side of the
spindle is splined, and not tapered. The left crank arm slides over
the splines and is held in place by two pinch bolts. BB bearings are
installed external to the BB shell. Bearing preload is achieved
with a bolt that threads into the hollow axle, shouldering against the
left crank, and pulls the whole assembly together. This design
appears to be very much like Shimano's modern cranks, although I have
not looked closely at the Shimano version.

I've had this crank on my cyclocross bike for about 3 months.
I've put maybe 1000 km on road, and perhaps 12 hrs of off road,
including a fair amount of steep uphill climbs. I weigh about 200 lb.

I found that in use, the preload bolt would gradually loosen, and the
left arm would walk off of the splines, even though the pinch bolts
were tight. As a result I began to ensure that the crank was
properly seated before each ride. With continued use, the splined
crank/spindle interface began to creak when pedaling out of the saddle.
As of now, the crank is still useable, but I can forcefully rock the
crank arm back and forth on the splines, with the pinch bolts tight.
I can't imagine this will last more than a few hundred km more before
failure.

I wonder if anyone has had similar experiences with this or other
cranks of this basic design?

I've had problems with mine. I've wondered whether or not I'm an
incompetent mechanic, but maybe it's the cranks. 8) When I first installed
them they came loose on a ride after a couple hundred miles were on them. I
managed to secure the left crank on the road and get home, but the event had
jammed the preload bolt (aluminum) and I had to destroy the threads to get
it out. In order to get the crank back on I used a quick release and a
piece of wood in place of the bolt to preload the bearings. I torqued down
the pinch bolts and removed the quick release. This fix worked for about
700 more miles until the other day when the crank came off again. I've
switched back to my Shimano Ultegra, but I miss the 34 tooth inner chain
ring.

BTW - I ordered a new preload bolt, but I'm unable to get it to thread into
the axle. The axle threads must have been damaged too. Not a good design.

Chuck Davis

I'm very aware of what you've been experiencing. My Gary Fisher Lane has gone through 2 sets of cranks and a bottom bracket because of this gross defect from FSA. I had my crank set literally blow apart one evening while riding home from work. FSA should be forced to make a recall of this crank set and offer anyone who had it come standard on a bike purchase a better system free of charge.