HOT: Active* forum members generally gain 5% discount at starbike.com store!
Weight Weenies
* FAQ    * Search    * Trending Topics
* Login   * Register
HOME Listings Articles FAQ Contact About




Post new topic Reply to topic  [ 24 posts ] 
Go to page 1, 2  Next
Author Message
PostPosted: Tue Jul 25, 2006 1:37 am 
Offline

Joined: Wed Mar 09, 2005 11:21 pm
Posts: 254
Location: Eureka, Ca.
Someone please explain to me how this happens?

1. Yes it was tight.
2. The crank bolt does not appear to be damaged, AND it extends further into the axel than where the break occured.

I got back from a ride and changed training wheels to my new Nimble Crosswinds to take them out for a spin. 1 block from my house I stand up to accelerate down the road and BLAM, my right crankarm is now no longer 180 degrees from my left. Very weird sensation. The crankarm stayed attached through all of this. Rode back home carefully and disassembled to find it in this configuration.

I have emailed KCNC to see if they want to warranty the item. It has always been tightened to spec, so I would assume this is a defect in the axel material itself. I only weigh 135lbs.

Chris


Attachments:
PICT0027.JPG
PICT0027.JPG [ 23.9 KiB | Viewed 1541 times ]
PICT0029.JPG
PICT0029.JPG [ 24.55 KiB | Viewed 1288 times ]
PICT0030.JPG
PICT0030.JPG [ 23.36 KiB | Viewed 6070 times ]
Top
 Profile  
 
Posted: Tue Jul 25, 2006 1:37 am 


Top
  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 1:41 am 
Offline
User avatar

Joined: Tue Apr 18, 2006 3:03 am
Posts: 1851
Location: Islip, NY
From what I've read, that is the weak point of ISIS. The BB design leads to a stress riser right where it looks like it broke. Maybe someone elso can verify this.

-Eric


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 1:44 am 
Offline
Shop Owner
User avatar

Joined: Sun Feb 06, 2005 4:22 pm
Posts: 3523
Location: Tucson, Az.
Not too uncommon with the scandium axels. I think the Ti is a much better way to go.

Did you have the stock bolts in the BB?

_________________
Fair Wheel Bikes

Fair Wheel Blog

Friend me on Facebook for behind the scenes updates


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 2:29 am 
Offline
User avatar

Joined: Fri May 21, 2004 7:31 pm
Posts: 531
Location: Stumptown USA
I wouldnt ride any scandium axled BB. Save weight someplace else.

_________________
PlusOneLap.com: Everything Cyclocross


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 2:55 am 
Offline

Joined: Mon Jul 10, 2006 1:38 am
Posts: 649
Location: Vancouver, BC
I agree with everyone else. The axle is cantilevered at the point it broke, and it undergoes a huge number of stress cycles (90 per minute on average... :) ). Without clearer photos, I'd say this was a case of fatigue failure. There may be ways to reduce the stress in the part through better design (i.e., not having an isis shaped spline), but aluminum - scandium doped or not - is not the greatest material for this application.

John Swanson

_________________
www.bikephysics.com
www.lanternart.com


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 8:23 am 
Offline
User avatar

Joined: Wed Feb 09, 2005 7:55 am
Posts: 942
Location: "On the other side of the pine lands", NY
I just bought the Token Scandium unit and installed it today, but didn't have time to ride. Hope I'm not posting the same story as chicane tomorrow. :frightened:

_________________
Aero beats weight - unless you're slow!


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 10:45 am 
Offline
User avatar

Joined: Sun Jan 08, 2006 5:53 pm
Posts: 1465
Location: Leiden, NETHERLANDS
Scandium is like Aluminium a metal that breaks immediately (if it breaks). Titanium is different and has the advantage that - before it will break - the metal will bend so you know when to replace it in time. Titanium is rarely to break at once.

For riders over 75-80kg I would not recommend Titanium BB and Scandium or Aluminium BB I would never recommend. The weight saving is not worth the risk .......

_________________
My bike is Italian so it is Nervosa and of course has Anorexia I like them thin!
GIOS "New" Carbon Ultra 2006 Campa Record+Special parts.
GIOS "New" A90 2008 Campa Record+Special parts. My winter and vacation bike.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 1:32 pm 
Offline
User avatar

Joined: Fri Mar 19, 2004 1:36 pm
Posts: 4123
The aluminum BB spindle from the Cannondale SI Hollowgram is very reliable and strong. Personally, I've been using it in my MTB for the past 4 years.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 4:10 pm 
Offline

Joined: Wed Mar 09, 2005 11:21 pm
Posts: 254
Location: Eureka, Ca.
madcow wrote:
Not too uncommon with the scandium axels. I think the Ti is a much better way to go.

Did you have the stock bolts in the BB?


I was using the standard bolts, which is what makes this failure weird. They extend very far into the axel (past the break), and were not damaged during the failure.

I agree about the Scandium BB in general. It always felt like a toy, so I have already ordered myself a replacement Token BB w/ TI axel (While this was sold as a KCNC, it looks identical to the Token, so I assume it was made by the same folks)


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 4:21 pm 
Offline
User avatar

Joined: Wed Feb 09, 2005 7:55 am
Posts: 942
Location: "On the other side of the pine lands", NY
I've got the OEM bolts installed and properly torqued also chicane, so I'm crossing my fingers at this point. I'm leaving in 20 minutes to take it on a 23-mile rolling "time-trial" ride, on which there are several quick stand-up climbs. I'm going to pour the beans to it and not baby it, so we'll see if it's going to hold up initially.

If it eventually borks, I'll probably give the Ti/CF version a try too. :? If that one dies, then I guess it's back to boat anchors for me. :(

Damned WW parts!!

_________________
Aero beats weight - unless you're slow!


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 8:17 pm 
Offline
Banned
User avatar

Joined: Tue Sep 06, 2005 1:33 am
Posts: 3468
Location: Hamilton, Canada
ride the thin edge of weeniedom, you'll get cut.

These aluminum axles are like aluminum cassettes: disposable for race-only bikes.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 9:41 pm 
Offline
User avatar

Joined: Thu Apr 08, 2004 7:03 pm
Posts: 252
Location: 52.5° N 1.7° W
onyourleft wrote:
I've got the OEM bolts installed and properly torqued also chicane, so I'm crossing my fingers at this point. I'm leaving in 20 minutes to take it on a 23-mile rolling "time-trial" ride, on which there are several quick stand-up climbs. I'm going to pour the beans to it and not baby it, so we'll see if it's going to hold up initially.

If it eventually borks, I'll probably give the Ti/CF version a try too. :? If that one dies, then I guess it's back to boat anchors for me. :(

Damned WW parts!!


Boat anchors haha :lol:

_________________
For if life, in the desire for which our essence and existence consists, possessed in itself a positive value and real content, there would be no such thing as boredom: mere existence would fufill and satisfy us.

Arthur Schopenhauer


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 9:46 pm 
Offline

Joined: Wed Oct 08, 2003 4:15 am
Posts: 3239
Location: tucson
divve wrote:
The aluminum BB spindle from the Cannondale SI Hollowgram is very reliable and strong. Personally, I've been using it in my MTB for the past 4 years.


The SI BB spindle is almost twice the diameter of an isis.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 10:24 pm 
Offline
User avatar

Joined: Fri Mar 19, 2004 1:36 pm
Posts: 4123
About 30mm versus 22mm. My point was that aluminum can be used for a BB spindle provided it's designed properly.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jul 25, 2006 11:57 pm 
Offline

Joined: Mon Jul 10, 2006 1:38 am
Posts: 649
Location: Vancouver, BC
Yes, I agree with most of the posts above. But it really doesn't look like it was a shear failure. To shear a piece of aluminum that size would take a horrendous impact. Like dropping an anvil on it from three stories up. I think what we're seeing here is a fatigue failure at the point of maximum stress.

I think an increase in diameter and a change in spline pattern could help in increasing fatigue life, but aluminum really isn't up to the task. Titanium would be much better since its fatigue characteristics are that much better.

John Swanson

_________________
www.bikephysics.com
www.lanternart.com


Top
 Profile  
 
 Post subject:
Posted: Tue Jul 25, 2006 11:57 pm 


Top
  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 24 posts ] 
Go to page 1, 2  Next


Who is online

Users browsing this forum: drainyoo, Google Adsense [Bot], Hbrown, hobopleb, Jdrsvin, kevhogaz, mika, rmerka, wheelsONfire and 99 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

   Similar Topics   Author   Replies   Views   Last post 
There are no new unread posts for this topic. KCNC Ti Cable

in Road

NiFTY

1

567

Tue Sep 17, 2013 7:04 pm

sanjay13leo View the latest post

There are no new unread posts for this topic. KCNC K3 Cobweb vs. Extralite Octaramp RC2 vs. ?

in Road

TexasWillis

5

733

Wed Oct 23, 2013 10:28 pm

Qman View the latest post

There are no new unread posts for this topic. KCNC titanium brake cables

in Road

bazmac

10

1158

Mon Jan 27, 2014 11:42 pm

drainyoo View the latest post

There are no new unread posts for this topic. KCNC Garmin Mount Review.

in Road

Shortsocks

4

513

Tue May 20, 2014 1:42 pm

53x12 View the latest post

There are no new unread posts for this topic. kcnc/felt expander plug help

in Road

digiadaamore

2

410

Sat Nov 09, 2013 11:28 am

Mackers View the latest post


It is currently Mon Jul 28, 2014 4:42 pm

All times are UTC + 1 hour




Advertising   –  FAQ   –  Contact   –  Convert   –  About

© Weight Weenies 2000-2013
hosted by starbike.com


How to get rid of these ads? Just register!


Powered by phpBB