BCD of sickbikeparts freewheel crank?

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BCD of sickbikeparts freewheel crank?

Postby Qwiksand » Fri Oct 22, 2010 8:50 am

Hi guys,

I searched, but to no avail...Does anyone know the BCD (bolt center diameter) of the the sickbikeparts.com freewheel, heavy duty or standard- they look like the same BCD on their site.

Image

http://www.sickbikeparts.com/catalog/product_info.php?cPath=21&products_id=62&osCsid=9krljtnmhr480dejk1smdulgm5
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Re: BCD of sickbikeparts freewheel crank?

Postby Thud » Fri Oct 22, 2010 9:00 am

From Miles:
Sick-bike freewheel BCD is 67.6mm
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Re: BCD of sickbikeparts freewheel crank?

Postby Miles » Fri Oct 22, 2010 9:23 am

Measured it again, to check: 67.5mm this time.

Close to 2-2/3"....? :?
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Re: BCD of sickbikeparts freewheel crank?

Postby Thud » Fri Oct 22, 2010 10:13 am

Its the common 2-21/32nd" bcd :mrgreen: ????????
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Re: BCD of sickbikeparts freewheel crank?

Postby Miles » Fri Oct 22, 2010 10:16 am

:mrgreen:
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Re: BCD of sickbikeparts freewheel crank?

Postby boostjuice » Fri Oct 22, 2010 8:45 pm

To quote Jim from Sickbikeparts

"The hub radius is 1.06 inches or a 2.12 diameter. The hole spacing is about
1.33 radius or 2.66 diameter in a 5 bolt pattern."

= 67.733333mm BCD

however, the word "about" doesn't exactly inspire confidence in the accuracy. :|
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Re: BCD of sickbikeparts freewheel crank?

Postby Qwiksand » Sat Oct 23, 2010 7:35 am

Thanks guys!
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Re: BCD of sickbikeparts freewheel crank?

Postby jdcburg » Sat Oct 23, 2010 8:52 am

From Wikipedia http://en.wikipedia.org/wiki/Wheel_sizing
Some basic geometry is needed to find the center of a 5-bolt pattern: But basically, the PCD can be found by multiplying the center distance between any two adjacent holes by 1.701. Generally, the PCD can be calculated for any wheel from the number of bolts (n) and the measured center distance between two adjacent bolts (d) as; PCD = d / SIN(180°/n).


I believe what they call PCD is BCD
In theory, there is no difference between theory and practice. But in practice, there is - Yogi Berra
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Re: BCD of sickbikeparts freewheel crank?

Postby HAL9000v2.0 » Sat Jan 29, 2011 7:51 am

boostjuice wrote:To quote Jim from Sickbikeparts

"The hub radius is 1.06 inches or a 2.12 diameter. The hole spacing is about
1.33 radius or 2.66 diameter in a 5 bolt pattern."

= 67.733333mm BCD

however, the word "about" doesn't exactly inspire confidence in the accuracy. :|



I am mesuring this for an hour now and measured this:
Measuring is made according to ISO17025 :)
Measured with 3 different

hub diameter is oval and it is between 53,68 and 53,73mm
Then I measured from top of the hole to outher dia (2,62) and measured hole (5,25mm). I measured outher diameter and found out it is 77,78 so calculated BCD:
77,78-(2x2,62)-5,25 = 67,29
Then I measured from one hole to another and calculated BCD from pentagon and the result was 67,31mm

Then I repeated all starting with different hole each time.
maximal result was 67,82mm
This pissed me off that I couldn't measure diameter so I am taking it to 3d probe on Monday.
I guess the circle with holes is not concentric with other circles.
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Re: BCD of sickbikeparts freewheel crank?

Postby spinningmagnets » Thu Feb 21, 2013 4:43 pm

The hub radius is 1.06 inches or a 2.12 diameter. The hole spacing is about
1.33 radius or 2.66 diameter in a 5 bolt pattern." = 67.7mm BCD


He should be beaten.

OK...(facepalms)...what are the diameters of the holes? and...

Is the interface the same as the ACS Crossfire flanged FW from Bikemotive/Staton?
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Re: BCD of sickbikeparts freewheel crank?

Postby Miles » Thu Feb 21, 2013 5:34 pm

spinningmagnets wrote:Is the interface the same as the ACS Crossfire flanged FW from Bikemotive/Staton?
I believe so..

spinningmagnets wrote:what are the diameters of the holes?
5mm on the ENO
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Re: BCD of sickbikeparts freewheel crank?

Postby Thud » Thu Feb 21, 2013 5:53 pm

On the crossfire's there are 5mm tapped holes & through holes with clearance for a 5mm bolt.
Yes they all line up..Eno, dicta & crossfire.
In English the bcd will measure 2.63"






I friggin hate the iPod auto spell! :!:
Last edited by Thud on Thu Feb 21, 2013 5:54 pm, edited 1 time in total. View post history.
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Re: BCD of sickbikeparts freewheel crank?

Postby spinningmagnets » Thu Feb 21, 2013 6:42 pm

I friggin hate the iPod auto spell


AH!...me too!

I was texting my ex-wife, and when I typed in "best of luck, and say hi to the kids when you see them",
it auto-corrected to:

"you ruined my life and left me penniless, you heartless monster"
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Re: BCD of sickbikeparts freewheel crank?

Postby Thud » Thu Feb 21, 2013 7:21 pm

:mrgreen:
get some......

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