bikerumor monday mystery pic

Photo from the collection of Rustybicycle. If you think you know what this is, post your answer in ‘comments’ section– the answer will be posted there on Tuesday! UPDATE: Answer in picture form is after the break.

To send in your own Mystery Pic to be considered for the Monday feature, click here and attach your photo with all pertinent information.

bikerumor mystery pic answer: cycle pro chain hook


  1. Must be a clip on old style pupmp holder. A chain guide would be designed to easily let the chain flow back onto the rings; can’t be a chain guide.

What do you think?