Speed Bump
Speed Bump is what I call a Crownring conversion product. Bolt on crowns adaptable to any chainring.
The purpose for having a bolt on crown is it gives skeptics an opportunity to explore the validity of Crownring without spending much, but more important, without permanently altering their bicycles. Speed bumps can be easily applied or removed in a matter of minutes.
The thing about bikes is they don't all have replaceable chainrings. Most of the bikes on the road have a chainring pressed or welded to to the right pedal stem. A change means replacing the entire assembly. Speed Bump allows conversion even to permanently mounted rings.
A Speed Bump conversion is likely going to require a chain enlargement. That means a chain tensioner if they want to swap back and forth. Although, if their conversion is permanent, the chain can be lengthened enough to accompdate the Speed Bumps and no tensioner is necessary. Adding a size (2) Speed Bump to a 44T chainring ups the draw to equal a 48T chainring. As the rotation does not alter the tooth count, 48T is 48T regardless of the position of the crowns.
However, putting a Speed Bump conversion on a mountain bike with three chainrings is only a matter of bolting them on the center ring. No other changes necessary. The chain length is already adequate. It makes the big ring superfluous as the center ring would then be just as fast as the big ring while retaining its original low radius. The rear derailleur provides chain tension.
Speed Bump is a practical product but its time has not yet arrived. It is purely an after market product. No one is going to buy Speed Bump before Crownring has established its validity. Once Crownring is making its way through the bicycle industry, Speed Bump will become a necessary addition to the Crownring family.
Text updated September 26, 2025
