Mysterious pedal insert failure

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wheelsONfire
Posts: 6280
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

I want to share with you a mysterious problem.
I bought a FSA K-Force Light BB 386 EVO crankset some time back.
The crankset was mounted as info sheet suggested to 100% proper.

One day something happened, which i can not really understand.
I was descending down a hill, i was going on roll so speed was just 55Km/h.
When i started to pedal, the drive side pedal just popped out and right foot smashed into ground and i was thrown forward onto handlebar.
Luckily i managed to brake down speed and steer bike away from cars, trees and not crashing!
I parked bike and walked to pick up pedal which was located a bit further away.
Looking at pedal spindle, i could detect torn thread pieces winded around the pedals threads.
Pedal is Time Xpresso 10, using stainless spindle, crank however uses some sort of aluminium (6061/7075 - who knows?)

I checked the cranks insert and it looked a bit damaged.
So i went home and cleaned the pedal spindle and damaged insert.

As far as i noted, i could see that pedal had actually unwind itself and when i started to pedal, it simply had unwinded to a point there was too little contact so it was torn out.
A friend told me i should have noted that this had happened, sure, i agree, but i did not.

I sent my crank back to FSA which had to inspect this. They suggested that i must have cross-threaded pedal into insert, but after inspection it was
obvious it was not the case.
To this date, i can't explain how this could happen and as far as i can see, neither can FSA.

Now as i got the crank returned tested and approved by FSA service team, i was and am pretty amazed that they did not warrant this.

Actually, when you thread a new pedal into the insert, it is rocking untill it is 100% bottomed out.
I could use it with Loctite 222 or 221, but to me this was and is not acceptable so i informed FSA of this.

The crank is not repairable at all. I needed to buy an all new crankset.
I got some discount, what is called crash replacement.
But this is not really what happened as you may understand (there was never any crash.

My question to you guys, what do you think made this strange thing happen?
You all know how a pedal and pedal insert is threaded, so it should be impossible.

In my opinion, i guess FSA should have replaced drive side without me being forced to buy and all new complete crankset.
Neither could i get a refund.

I still claim, the crankset shift very well and except this issue, i like the crankset.

What do you guys think?
Bikes:

Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)


Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.

by Weenie


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EcoRacer
Posts: 39
Joined: Thu Dec 09, 2010 8:13 pm
Location: Oslo, Norway

by EcoRacer

You are not going to want to read this, but:

As an ex-FSA Warranty rep I can tell you that problems with the pedal threads, have never been covered under warranty by FSA. (check the manual for reference) This is not specific to FSA, this is for almost all crankset manufacturers. This is due to the great possibility for user error while mounting pedals. I agree, in a case like this that is hard to understand, but that is the way the system works. Your only chance is that you meet a nice warranty rep who really wants to help. But if FSA says NO! than he is not going to get very far. Unless they want to pay out of their own pocket. I have done that before to help out a customer, but not everyone is willing to do this.

If there was no manufacturing issue with the crankarm there is no reason for FSA to give you a new one.

In the end it is up to the bike user to check all fasteners on his bike periodically as stated in all manuals. As part of regular service.

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wheelsONfire
Posts: 6280
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

^
Thanks EcoRacer!

This specific pedal was torqued and i had used the bike 2 times (fail was the second ride after pedal was torqued).
I know FSA do not warrant threads, i checked the policy for warranty issues.

It's great fun using a crankset 5 times and being forced to buy an all new.
Nah, not so much.

I hope i'll never see this again.
Bikes:

Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)


Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.

Hawkwood
Posts: 334
Joined: Tue Apr 07, 2009 4:27 pm

by Hawkwood

Can a pedal `unwind itself'? I thought the problem with pedals is that they can gradually tighten in the crank thread, this was certainly a problem years ago, and it could be a real pain trying to take a pedal off. I'm using Time Xpresso pedals on a Rotor crankset and the pedals screw in really smoothly and stay there.

Marin
Posts: 4035
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

Sorry, this sounds like an installation error.

What could possibly be wrong with the crank threads? It's not like the insert itself broke out of the arm.

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EcoRacer
Posts: 39
Joined: Thu Dec 09, 2010 8:13 pm
Location: Oslo, Norway

by EcoRacer

FSA are not always the easiest bunch to deal with.
To say it lightly we did not agree on a lot of points. :lol:

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wheelsONfire
Posts: 6280
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

How can you install a pedal wrong?
Let's see, you can cross thread it, what more?
Obviously it was not cross threaded, they had noticed that at service center.
So Marin, what other suggestions do you have to back up that suggestion?
I am eager to hear.
I work at times with tool changes, so i am more or less forced to work with bolts and nuts.
I think it is pretty easy to determine if you start to thread something wrong.

Yes, the question remains, how is it possible for a pedal to unwind, i have tried to figure this one out, but i really have no idea!
Bikes:

Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)


Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.

joec
Posts: 100
Joined: Wed Mar 05, 2014 9:20 pm

by joec

unfortunatly pedals do unwind occasionally, although they are threaded "the other way" so they should do up, the rocking of pedaling can still unwind them, its somthing i do a check of occasionally.

depending what side it is you could get the thred helicoiled ( it can be one both sides but the lh threaded helicoil kit would probqbly be pretty pricy)

5 8 5
Posts: 1315
Joined: Sat Jul 29, 2006 2:36 am
Location: UK

by 5 8 5

wheelsONfire, glad you're okay - scarey stuff!

I've seen it happen to a couple of riders where a pedal has come loose during a ride but hasn't come out completely.
One re-tightened the pedal and it was fine. The other re-tightened the pedal to get home but the threads were badly damaged and the crank had to be binned.
Fortunately it was an old alloy crank.

I'm not sure why they came loose but I suspect they weren't tightened enough because I've worked on a couple of friends bikes and the pedals were not tight enough.

wheelsONfire wrote:Actually, when you thread a new pedal into the insert, it is rocking untill it is 100% bottomed out.
I could use it with Loctite 222 or 221, but to me this was and is not acceptable so i informed FSA of this.

The rocking is normal (pedal threads have big pitch) but it does vary brand to brand. I'd recommend medium strength Loctite 243 due to the size of the threads.
It might not stop the pedal from coming a little bit loose but it would stop it from unwinding completely. You could try it on a turbo to see if it's okay.

But first take the crank and pedal to a bike shop. They can chase the threads and examine the damage. Also get them to measure the pedal axle to see if it's undersize (unlikely).

wheelsONfire wrote:My question to you guys, what do you think made this strange thing happen?
You all know how a pedal and pedal insert is threaded, so it should be impossible.

It's a myth that pedals tighten while riding. Did you fit the pedals yourself or was it a bike shop?

After the first ride all bolts should be checked, again after the second and then periodically after that.
The logical explanation is that it wasn't tight enough. Road vibration and out of the saddle riding could loosen it even more.
I'm surprised you didn't get any warning - clicking or creaking before it happened. The main thing is you're okay.

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pdlpsher1
Posts: 4013
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

I've had the same thing happen once. It was scary for sure as it happened on a downhill. I ended up riding home one legged as I wasn't able to thread the pedal back on the crank without a wrench. Once I fixed the problem at home everything is fine. I never figured out why it happend the way it did. You might want to try using a lock washer as opposed to Loctite. This will give you some peace of mind.

Valbrona
Posts: 1629
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

Did the FSA instruction manual say that you need to fit pedal washers, and did a pair come with the crankset? If so you chose the wrong pedal/crank combination as Time pedals have only short sections of thread which may not have given the minimum amount of insertion as per Time pedal instruction sheet.

lannes
Posts: 418
Joined: Sat Nov 10, 2007 9:51 pm

by lannes

Maybe there is excessive flex in the pedal axle , the wiggling of the axle may have worked the pedal loose where the threads on the pedal axle and the insert did not have a close enough tolerance.

It could be the minimum insertion issue , did you use washer on the axle ?

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wheelsONfire
Posts: 6280
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

FSA has it's own washers which i did use.

Pedals had torque at 12-14Nm and mounted as instruction demanded.
I have never had a pedal come loose before. Never heard of it even.
However, using grease on threads or Loctite, those two are really each others opposite!

I try to figure what to do on the new crankset. Should i use Loctite on the none drive side crank arm (38-41Nm) and possibly even pedals?
I used 222 on some small bolts on a Harley and it worked. On a R1 i had the bike in for service and also had some kit installed (shift, brake aso).
When i rode home, the shift lever dropped so i could not shift at all.
The dealer had to go same route by car and pick the things up.
When we met, i told him, you did not use Loctite as i told you?
Nope, you should not do that he told me. He torqued the parts again and went home.

I took all parts off myself and used 222 and after that, no problems.
He was a professional speedway mechanic.
I mailed the company who constructed these parts and they told me i need no Loctite.
To me, in this case it was pretty obvious i actually did.

But a bike... i am not sure. Perhaps it is enough if i just skip using grease?
Grease alone help the pedal and crank arm unwind more easy.

What do you guys think?
Bikes:

Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)


Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.

hasbeen
Posts: 531
Joined: Tue Feb 07, 2012 7:17 pm

by hasbeen

pedal washer may not have been flush when mounted. the fact that this was the left pedal means it just wasnt tight enough. unfortunately an installation accident most likely. if it happens it is almost always left side no matter who make the cranks. also, old pedal threads?
Casati Vola SLi and Dolan Preffisio
viewtopic.php?f=10&t=108931" onclick="window.open(this.href);return false;"
btompkins0112 wrote:
It has the H2 geo......one step racier than a hybrid bike

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wheelsONfire
Posts: 6280
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

Nope, right pedal and pedal threads are still excellent.
It is stainless steel threads so there is no damage.
Yes, ofcourse washer was flush!!
You could not torque a pedal at 12-14Nm without checking if a washers is flush first ;-)
Pedal threads are cleaned and inspected so nope, not a correct assessment.
The crank was also new.
Bikes:

Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)


Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



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