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 to the Forum - Introduction Yesterday 05:38 PM
Would you like a pizza after cycling? Yesterday 02:10 AM
Hardtail as only bike? 07-12-2026 05:23 PM
Spoke Count Preference 07-12-2026 09:17 AM
Pros & Cons of presta valve vs schrader ... 07-12-2026 03:34 AM
Are you mainly into Mountain Biking, Roa... 07-12-2026 02:20 AM
New around here 07-11-2026 10:53 AM
Favorite MTB brand? 07-10-2026 03:16 AM
29"front & 26" rear? Thoughts? 07-10-2026 03:13 AM
suspicious broken part after service--is... 07-09-2026 02:45 PM

Join BikeRide on Strava

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