Thorn Cycles Forum

Technical => Transmission => Topic started by: Andre Jute on February 05, 2016, 12:02:40 am

Title: Preworn teeth, and only every second one at that, in future Shimano chainrings
Post by: Andre Jute on February 05, 2016, 12:02:40 am

(http://brimages.bikeboardmedia.netdna-cdn.com/wp-content/uploads/2016/01/shimano-chainring-alternating-tooth-gaps-patent-drawing-1.jpg)

The image is from BikeRumor (http://www.bikerumor.com/2016/02/01/is-shimano-losing-teeth-to-make-lighter-better-shifting-chainrings/)
http://www.bikerumor.com/2016/02/01/is-shimano-losing-teeth-to-make-lighter-better-shifting-chainrings/
where the editors explain:
"Want to reduce weight? Cut drag and friction? Easy, just remove every other tooth."

Yup, and pre-degrade the teeth, which will save 9.137529 (recurring) nanograms of mass.

Joking aside, there's a good deal of technical interest in that article of possible ways to lay out driving teeth.

Title: Re: Preworn teeth, and only every second one at that, in future Shimano chainrings
Post by: Bill C on February 05, 2016, 12:34:55 am

looks a lot like inch pitch, i spose it uses an i-chain  ::) ? it will be elliptical chain rings next, this modern tech stuff where will it all end?

Title: Re: Preworn teeth, and only every second one at that, in future Shimano chainrings
Post by: mickeg on February 05, 2016, 02:23:08 pm

I have seen track chainrings that look like that in the past, but that was not for derailleur bikes.

I took the attached photos in the Smithsonian Institute in spring 2013, a museum in Washington D.C.  The camera I had does not have a good flash, so I was trying to take photos without the flash, but it was quite dark so the photos are pretty poor.  Sorry.  The first two photos have a vintage bike with that same tooth pattern on the chainring.  I do not recall for sure, but it is possible that this was a Wright Brothers bicycle.

The third photo, is that a chainglider?

Title: Re: Preworn teeth, and only every second one at that, in future Shimano chainrings
Post by: Bill C on February 05, 2016, 07:24:11 pm

some more pics here http://bikecult.com/works/chainwheel.html

Title: Re: Preworn teeth, and only every second one at that, in future Shimano chainrings
Post by: Andre Jute on February 05, 2016, 11:13:12 pm

It looks like early cycling manufacturers soon agreed on an inch-pitch, Bill.

That surely looks like an early Chainglider, George. Presumably the wax model is of Major Taylor, the early cycling hero.

Title: Re: Preworn teeth, and only every second one at that, in future Shimano chainrings
Post by: il padrone on February 08, 2016, 06:42:02 am

Quote from: Andre Jute on February 05, 2016, 11:13:12 pm

It looks like early cycling manufacturers soon agreed on an inch-pitch, Bill.

That surely looks like an early Chainglider, George. Presumably the wax model is of Major Taylor, the early cycling hero.

Major Taylor was a black man  ???

Title: Re: Preworn teeth, and only every second one at that, in future Shimano chainrings
Post by: Andre Jute on February 08, 2016, 07:49:56 am

Quote from: il padrone on February 08, 2016, 06:42:02 am

Quote from: Andre Jute on February 05, 2016, 11:13:12 pm

Presumably the wax model is of Major Taylor, the early cycling hero.

Major Taylor was a black man  ???

(http://thorncyclesforum.co.uk/index.php?action=dlattach;topic=11640.0;attach=11954;image)

Title: Re: Preworn teeth, and only every second one at that, in future Shimano chainrings
Post by: il padrone on February 08, 2016, 11:02:28 am

Guess my colour-blindness is playing up. That dummy does not look black to me ???  ???