A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

carbon crank scratched - concern?



 
 
Thread Tools Display Modes
  #1  
Old April 24th 20, 09:41 PM posted to rec.bicycles.tech
Ted Heise
external usenet poster
 
Posts: 136
Default carbon crank scratched - concern?


Hi all,

A couple of days ago I noticed a scratch on a carbon crank. Pics
are he

http://www.panix.com/~theise/IMG_7765.jpg

http://www.panix.com/~theise/IMG_7766.jpg

It's on my tandem, so I'm especially senstive to safety. The
scratch does not feel as if it has much depth to it. I think it
may have happened when I lost my balance getting off, and could
potentially have banged it with the Speedplay cleat on the bottom
of my shoe.

Should I be concerned about failure?

As an aside, I wasn't paying enough attention when I ordered this
bike. I specifically wanted titanlum for resistance to cosmetic
damage, but would have preferred *not* to have carbon components
(also for resistance to handling damage).

Thanks for any advice!

--
Ted Heise West Lafayette, IN, USA
Ads
  #2  
Old April 24th 20, 09:58 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 824
Default carbon crank scratched - concern?

On Friday, April 24, 2020 at 10:41:10 PM UTC+2, Ted Heise wrote:
Hi all,

A couple of days ago I noticed a scratch on a carbon crank. Pics
are he

http://www.panix.com/~theise/IMG_7765.jpg

http://www.panix.com/~theise/IMG_7766.jpg

It's on my tandem, so I'm especially senstive to safety. The
scratch does not feel as if it has much depth to it. I think it
may have happened when I lost my balance getting off, and could
potentially have banged it with the Speedplay cleat on the bottom
of my shoe.

Should I be concerned about failure?

As an aside, I wasn't paying enough attention when I ordered this
bike. I specifically wanted titanlum for resistance to cosmetic
damage, but would have preferred *not* to have carbon components
(also for resistance to handling damage).

Thanks for any advice!

--
Ted Heise West Lafayette, IN, USA


That just looks like a scratch on the clear coat. I wouldn't worry.

Lou
  #3  
Old April 24th 20, 10:00 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 824
Default carbon crank scratched - concern?

On Friday, April 24, 2020 at 10:58:14 PM UTC+2, wrote:
On Friday, April 24, 2020 at 10:41:10 PM UTC+2, Ted Heise wrote:
Hi all,

A couple of days ago I noticed a scratch on a carbon crank. Pics
are he

http://www.panix.com/~theise/IMG_7765.jpg

http://www.panix.com/~theise/IMG_7766.jpg

It's on my tandem, so I'm especially senstive to safety. The
scratch does not feel as if it has much depth to it. I think it
may have happened when I lost my balance getting off, and could
potentially have banged it with the Speedplay cleat on the bottom
of my shoe.

Should I be concerned about failure?

As an aside, I wasn't paying enough attention when I ordered this
bike. I specifically wanted titanlum for resistance to cosmetic
damage, but would have preferred *not* to have carbon components
(also for resistance to handling damage).

Thanks for any advice!

--
Ted Heise West Lafayette, IN, USA


That just looks like a scratch on the clear coat. I wouldn't worry.

Lou



Get some car polish and it will look better.

Lou
  #4  
Old April 24th 20, 10:01 PM posted to rec.bicycles.tech
Joerg[_2_]
external usenet poster
 
Posts: 6,016
Default carbon crank scratched - concern?

On 2020-04-24 13:41, Ted Heise wrote:
Hi all,

A couple of days ago I noticed a scratch on a carbon crank. Pics
are he

http://www.panix.com/~theise/IMG_7765.jpg

http://www.panix.com/~theise/IMG_7766.jpg

It's on my tandem, so I'm especially senstive to safety. The
scratch does not feel as if it has much depth to it. I think it
may have happened when I lost my balance getting off, and could
potentially have banged it with the Speedplay cleat on the bottom
of my shoe.

Should I be concerned about failure?

As an aside, I wasn't paying enough attention when I ordered this
bike. I specifically wanted titanlum for resistance to cosmetic
damage, but would have preferred *not* to have carbon components
(also for resistance to handling damage).

Thanks for any advice!


I'd be more concerned about that apple-shaped outline above the scratch,
very visible in the 2nd photo link.

Personally I do not like carbon components where structural failure
could cause a lot of grief. I'd get new metal cranks, even if it's just
for peace of mind.

I guess this guy was lucky:

http://www.bustedcarbon.com/2009/02/...falls-off.html

--
Regards, Joerg

http://www.analogconsultants.com/
  #5  
Old April 24th 20, 11:25 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 13,447
Default carbon crank scratched - concern?

On 4/24/2020 3:41 PM, Ted Heise wrote:
Hi all,

A couple of days ago I noticed a scratch on a carbon crank. Pics
are he

http://www.panix.com/~theise/IMG_7765.jpg

http://www.panix.com/~theise/IMG_7766.jpg

It's on my tandem, so I'm especially senstive to safety. The
scratch does not feel as if it has much depth to it. I think it
may have happened when I lost my balance getting off, and could
potentially have banged it with the Speedplay cleat on the bottom
of my shoe.

Should I be concerned about failure?

As an aside, I wasn't paying enough attention when I ordered this
bike. I specifically wanted titanlum for resistance to cosmetic
damage, but would have preferred *not* to have carbon components
(also for resistance to handling damage).

Thanks for any advice!


Ask your dealer to examine the crank to see if it's merely a
cleat scratch or if it is indeed cracked. If it's cracked,
ask about warranty. Examine the other three as well (direct
sunlight and a magnifier).

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #6  
Old April 25th 20, 12:42 AM posted to rec.bicycles.tech
Sir Ridesalot
external usenet poster
 
Posts: 5,270
Default carbon crank scratched - concern?

On Friday, 24 April 2020 17:01:03 UTC-4, Joerg wrote:
On 2020-04-24 13:41, Ted Heise wrote:
Hi all,

A couple of days ago I noticed a scratch on a carbon crank. Pics
are he

http://www.panix.com/~theise/IMG_7765.jpg

http://www.panix.com/~theise/IMG_7766.jpg

It's on my tandem, so I'm especially senstive to safety. The
scratch does not feel as if it has much depth to it. I think it
may have happened when I lost my balance getting off, and could
potentially have banged it with the Speedplay cleat on the bottom
of my shoe.

Should I be concerned about failure?

As an aside, I wasn't paying enough attention when I ordered this
bike. I specifically wanted titanlum for resistance to cosmetic
damage, but would have preferred *not* to have carbon components
(also for resistance to handling damage).

Thanks for any advice!


I'd be more concerned about that apple-shaped outline above the scratch,
very visible in the 2nd photo link.

Personally I do not like carbon components where structural failure
could cause a lot of grief. I'd get new metal cranks, even if it's just
for peace of mind.

I guess this guy was lucky:

http://www.bustedcarbon.com/2009/02/...falls-off.html

--
Regards, Joerg

http://www.analogconsultants.com/


There were a lot of busted metal alloy crankarms too.

Cheers
  #7  
Old April 25th 20, 01:21 AM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 5,870
Default carbon crank scratched - concern?

On Friday, April 24, 2020 at 1:41:10 PM UTC-7, Ted Heise wrote:
Hi all,

A couple of days ago I noticed a scratch on a carbon crank. Pics
are he

http://www.panix.com/~theise/IMG_7765.jpg

http://www.panix.com/~theise/IMG_7766.jpg

It's on my tandem, so I'm especially senstive to safety. The
scratch does not feel as if it has much depth to it. I think it
may have happened when I lost my balance getting off, and could
potentially have banged it with the Speedplay cleat on the bottom
of my shoe.

Should I be concerned about failure?

As an aside, I wasn't paying enough attention when I ordered this
bike. I specifically wanted titanlum for resistance to cosmetic
damage, but would have preferred *not* to have carbon components
(also for resistance to handling damage).

Thanks for any advice!


If that arm fails, you have three others. I wouldn't worry. Seriously though, it looks like a scuff to the clearcoat. But do like Andrew says and take a close look.

I've failed two CF cranks at the pedal eyes. The threaded inserts tend to separate from the surrounding carbon lay-up or crack or the carbon cracks. One crank was OE SRAM Red on a Cannondale and the other was an ISIS POS FSA that I got on sale (and regretted). I wouldn't bother with CF cranks. With your Ti bike, you need these: https://www.youtube.com/watch?v=hx2rAWz_u3k And the $150 30mm threaded BSA bottom bracket and spacer kit (times two).

-- Jay Beattie.



  #8  
Old April 25th 20, 09:30 AM posted to rec.bicycles.tech
James[_8_]
external usenet poster
 
Posts: 6,153
Default carbon crank scratched - concern?

On 25/4/20 6:41 am, Ted Heise wrote:
Hi all,

A couple of days ago I noticed a scratch on a carbon crank. Pics
are he

http://www.panix.com/~theise/IMG_7765.jpg

http://www.panix.com/~theise/IMG_7766.jpg

It's on my tandem, so I'm especially senstive to safety. The
scratch does not feel as if it has much depth to it. I think it
may have happened when I lost my balance getting off, and could
potentially have banged it with the Speedplay cleat on the bottom
of my shoe.

Should I be concerned about failure?

As an aside, I wasn't paying enough attention when I ordered this
bike. I specifically wanted titanlum for resistance to cosmetic
damage, but would have preferred *not* to have carbon components
(also for resistance to handling damage).

Thanks for any advice!



It doesn't look worth worrying about, but if you're still concerned, why
not take it to a CF frame repairer and ask their opinion? They can
probably repair the scratch relatively cheaply too, if you want.

Titanium and aluminium are not immune to breakage. Both are notch
sensitive. That means if you scratch either metal, the scratch will
likely be the source of a crack, if the metal is stressed highly enough
and often enough. Steel doesn't suffer the same sort of problem. It
will rust though.

--
JS
  #9  
Old April 25th 20, 09:39 AM posted to rec.bicycles.tech
James[_8_]
external usenet poster
 
Posts: 6,153
Default carbon crank scratched - concern?

On 25/4/20 10:21 am, jbeattie wrote:


I've failed two CF cranks at the pedal eyes. The threaded inserts
tend to separate from the surrounding carbon lay-up or crack or the
carbon cracks. One crank was OE SRAM Red on a Cannondale and the
other was an ISIS POS FSA that I got on sale (and regretted). I
wouldn't bother with CF cranks.



Wow you have a bad time. I pounded out another 120km today over rough
roads and climbs up to 15% with my Campagnolo UT cranks. Never been a
problem.

Do the threaded inserts come adrift when you remove or tighten pedals,
or just happens while you're riding?

I use my chain lube wax & oil mix to lubricate my pedal threads, and
only tighten them on to the crank with maybe 10 Nm of torque? They are
never difficult to remove, and don't unwind of their own free will.

I have seen pedals loosen, but only because the pedal bearings were near
seized. Not on my bike.

--
JS
  #10  
Old April 25th 20, 04:12 PM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 5,870
Default carbon crank scratched - concern?

On Saturday, April 25, 2020 at 1:39:51 AM UTC-7, James wrote:
On 25/4/20 10:21 am, jbeattie wrote:


I've failed two CF cranks at the pedal eyes. The threaded inserts
tend to separate from the surrounding carbon lay-up or crack or the
carbon cracks. One crank was OE SRAM Red on a Cannondale and the
other was an ISIS POS FSA that I got on sale (and regretted). I
wouldn't bother with CF cranks.



Wow you have a bad time. I pounded out another 120km today over rough
roads and climbs up to 15% with my Campagnolo UT cranks. Never been a
problem.

Do the threaded inserts come adrift when you remove or tighten pedals,
or just happens while you're riding?


The threaded insert either cracked or separated from the surrounding lay-up or both. SRAM acknowledged the problem -- which is not uncommon bonding dissimilar materials. It happened during riding an not disassembly.

I use my chain lube wax & oil mix to lubricate my pedal threads, and
only tighten them on to the crank with maybe 10 Nm of torque? They are
never difficult to remove, and don't unwind of their own free will.

I have seen pedals loosen, but only because the pedal bearings were near
seized. Not on my bike.


The problem is not with the pedal seizing. I use ordinary anti-seize on my pedals -- with washers to avoid CF damage. BTW typical torque spec for pedals is 30-40 Nm -- or even higher for some mfg.

-- Jay Beattie.



 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Arrogant BMW driver gets his car scratched [email protected] UK 15 March 24th 18 10:17 AM
scratched rim after wipeout [email protected] Techniques 4 October 20th 08 04:59 PM
Repairing a scratched rim? Colin Campbell Techniques 4 January 2nd 07 05:24 PM
Repairing a scratched rim? Colin Campbell Techniques 0 January 2nd 07 01:05 AM
how scratched is your trials uni dubmuni2004 Unicycling 11 June 24th 04 03:18 AM


All times are GMT +1. The time now is 11:33 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.