The idea for an idler tensioner is interesting and homemade is great. Thought maybe use an older drive sprocket on a bearing (skate bearing?) would engage the chain better and have less chance of the bracket from slipping and accidentally hitting the chain with unwanted consequences. The biggest issue to me is that chains never stretch evenly so if it should get out of sync with the center stand spring tension with the sprocket or roller in a corner especially might be problematic.

Thanks for sharing your builds!

PJ