Chainring bumps and holes [Solved]

barracuda · 07-19-2019, 06:58 AM

After all these years I had never observed by commuter's chainrings and the interesting shapes they have. Do these holes and "bumps" help with the chain flow or what's the purpose?

G_M · 07-19-2019, 07:56 AM

(07-19-2019, 06:58 AM)barracuda Wrote: After all these years I had never observed by commuter's chainrings and the interesting shapes they have. Do these holes and "bumps" help with the chain flow or what's the purpose?

Exactly, those are called 'pins and ramps' and they support the upshifting. You can read about it on Sheldon Brown's page.

barracuda · 07-23-2019, 06:14 PM

(07-19-2019, 07:56 AM)G_M Wrote:
(07-19-2019, 06:58 AM)barracuda Wrote: After all these years I had never observed by commuter's chainrings and the interesting shapes they have. Do these holes and "bumps" help with the chain flow or what's the purpose?

Exactly, those are called 'pins and ramps' and they support the upshifting. You can read about it on Sheldon Brown's page.

Much appreciated, thanks!

10 Latest Posts
New rider Yesterday 11:27 PM
Mountain Biking with or with out sunglas... Yesterday 11:23 PM
How Bad Are E-bikes By You? Yesterday 11:12 PM
Catastrophic bicycle failures Yesterday 11:08 PM
2007 Trek Pilot S.P.A. 5.2 Yesterday 05:40 PM
I don't usually wear a bike helmet. Does... Yesterday 03:51 PM
Impromptu bikepacking/touring dilemma.. 10-01-2026 08:38 PM
Bmx with 26 inch wheels 10-01-2026 05:50 PM
Gila Monster Gran Fondo 10-01-2026 05:41 PM
Hatch Chiles Rule! 10-01-2026 05:10 PM

Join BikeRide on Strava

Feel free to join if you are on Strava: www.strava.com/clubs/bikeridecom