Talk:Crankset

Pedal Thread Pitch
"with 20 TPI (a thread pitch unique to bike pedals)." - MAlvis (22:46, 15 November 2006)


 * While Sheldon Brown confirms the 20 TPI, my Sears/Craftsman 50 Piece Tap and Die Set (hardly anything fancy) contains dies of size 1/2 x 20, 7/16 x 20, and everyone's favorite 1/4 x 20. Also, my Park Tool pedal taps are labeled only 9/16 x 20 (LH and RH), and the pitch matches exactly the right hand 1/2 x 20 tap that comes in the Sears set. I'm skeptical of the claim that 20 TPI is "a thread pitch unique to bike pedals." Does anyone have a source or additional information? -AndrewDressel 21:06, 16 November 2006 (UTC)


 * Okay, so while 20 TPI is the correct pitch, there doesn't appear to be any evidence that it is unique to bicycle pedals. I'll remove that statement. -AndrewDressel 14:41, 22 November 2006 (UTC)

My error, unintended, was perhaps one of wording clarity, not technical accuracy. It is the "size & thread pitch" combination which is unique to bike pedals, see http://www.sizes.com/tools/thread_american.htm, as one of many examples, including your one Sears marketed tap & die set.

The SAE standard fine thread pitch for bolt size 9/16" is 18 TPI, not 20 TPI. No major bolt/nut, tap/die, or thread repair device manufacturer (including any custom product manufacturer I could find) in the U.S. or abroad, offers any products in a 9/16" x 20 TPI combination, even in only a RH tread. After a rather extensive Google search (broadband connection), Park (previously unknown to me) was the only manufacturer I could find which offered any 9/16" x 20 TPI taps, RH & LH threads (which I ordered from the lowest cost net retailer I could find); they do not offer dies in this size.

TPI is an individual characteristic; the reason TPI gauges are routinely supplied in better quality tap and die sets. As with all fastening systems, it is combinations of characteristics which come to be recognized as standards, not individual characteristics. My comment about the "9/16 in. x 20 TPI" combination being quite unique to bicycle pedals is factually correct, an apparent historical but accepted event in the history of bicycle part manufacturers, assemblers and retailers. "9/16 in. x 20 TPI" is neither a United States (SAE: Society of Automotive Engineers, sae.org usually the dominant authority) or a metric standard. Given current practice to manufacture bicycle cranks from aluminum, the 20 TPI standard, as opposed to the national course "9/16 in. x 12 TPI" standard, which provides a much deeper thread, renders bicycle pedal bolts more prone to stripping out the finer/shallower 20 TPI treads within bicycle cranks. It is also the reason many local bicycle shops either carry specialized repair kits for bicycle cranks (generally rated as of poor reliability by many in the bicycle business) and/or sell crank replacements.

The above issues are part of the reason I ended up doing a search on the "9/16 in. x 20 TPI" engineering odyssey. Having extensive mechanical engineering experience and some small scale manufacturing capability, I elected to purchase the Park taps and will manufacture my own steel inserts from center-drilled grade 8 bolts and in-turn drill, tap and epoxy these custome inserts into cranks needing repair. This should end up more reliable than most currently available cranks, in terms of pedal thread toughness.

As such, and for the benefit of others, I would suggest that you correct, rather than delete the comment about "9/16 in. x 20 TPI" being unique to bicycle pedals. Thank you. MA | T@lk  14:56, 26 November 2006 (UTC)


 * Okay, I've put something back in. -AndrewDressel 18:15, 28 November 2006 (UTC)

I believe that you will find that 20 TPI is an old BS Cycle Thread Coarse measurement. I'm well experience in "odd" threads as a Norton and Soviet bike owner. I believe that Bicycle Tap and Die sets are still manufactured in Russia and other parts of the FSU and you should be able to find those dies. M-72 07:38, 19 December 2006 (UTC)


 * Re availability 9/16 20TPI This thread is widely used on Vincent motorcycles (60 years on and still get all the spares). 14:16, 9 November 2012 (UTC) Tim  <  — Preceding unsigned comment added by Timetc (talk • contribs) 11:47, 9 November 2012 (UTC)

Chainset
Chainset now redirects to Crankset --Skyleth 13:53, 18 February 2007 (UTC)


 * I'm not familiar with the term "chainset", could someone clarify where it's used? I assume it's a regional term. --Keithonearth (talk) 19:47, 5 July 2009 (UTC)


 * It is not in the OED, but then neither is "crankset". -AndrewDressel (talk) 14:35, 5 September 2011 (UTC)

Left-side drive
I can't find a source to confirm either one of these claims. Can anyone else? -AndrewDressel (talk) 14:13, 28 March 2008 (UTC)
 * 1) "Introduced by Profile BMX in the late 1990s for BMX riders who grind on their right side"
 * 2) "Introduced by Specialized in the late 1990s for BMX riders who grind on their right side"

Gearing
It might be worth mentioning that altering the length of the crank alters the effective gearing, inches development doesn't change, but leverage does in any particular gear. This is discussed in Sheldon Brown's gain ratio page. —Preceding unsigned comment added by 203.59.177.34 (talk) 02:17, 6 June 2008 (UTC)

Merger proposal
The content from Rotor(Crank) could be merged into this article under Crankset
 * Cabe 6403  (Talk•Please Sign my guest book!) 23:51, 16 October 2008 (UTC)
 * I've gone ahead and added the info from Rotor(Crank) into the main article Cabe  6403  (Talk•Please Sign my guest book!) 06:51, 17 October 2008 (UTC)
 * Good move. -AndrewDressel (talk) 14:08, 17 October 2008 (UTC)

Chain Ring
Should this be spun off to its own entry? Currently Chain Ring redirects somewhere quite unhelpful. 220.233.42.204 (talk) 11:35, 5 July 2009 (UTC)


 * I just found chain ring (spelt as two words) in the OED: n. (b) Cycling a sprocket on a bicycle which transfers power from the cranks to the (rear) wheel by means of a chain, so I've created a disambiguation page to which both spellings redirect. -AndrewDressel (talk) 14:00, 5 September 2011 (UTC)

Axle Diameter size
It worth mentioning the different sizes of axles diameters and the standard (24 mm shimano etc.) same size axle means that one can change BB from the original and it will stay compatible. --Nathandor (talk) 08:26, 6 November 2010 (UTC)

Center to Center Chainring Spacings?
Your page seems to miss out this basic data. With the front shifter's cable pull it allows knowledge of the front derailleur's shift ratio, (actuation ratio). I notice that some spacings are about 10mm while others are closer to 6mm, but the data seems only to be available by measurement. Nonetheless a few such dimensions would be useful. Are double and triple spacings the same? Ronpedia (talk) 13:35, 5 September 2011 (UTC)


 * I can find no mention of chainring spacing in any of my sources. Not even Berto's "updated and expanded" The Dancing Chain mentions it despite extensive coverage of differences in the number of teeth supported between adjacent chainrings. -AndrewDressel (talk) 14:06, 5 September 2011 (UTC)

Expanding chainrings
Expanding chainrings seem to be repeatedly invented and fail.

They are a more complex form of Expanding pulleys, which seem just as dubious with pages of patents and little actual use.

I suggest they be added to the article, but this requires some hairy net spelunking for sources. Musaran (talk) 20:49, 29 October 2016 (UTC)

Crank sizes for child Bicycles
There seem to be some thoughts lowering the crank size for children's bikes can lead to the center of gravity of the bicycle being lowered which may be beneficial for children. I dont want to do a bad edit a B-Class article on this. Thankyou. Djm-leighpark (talk) 08:12, 26 June 2018 (UTC)


 * I don't know who is thinking this, but I wonder how they think a lower center of mass may be beneficial for children. -AndrewDressel (talk) 12:08, 27 June 2018 (UTC)

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