Hello. I am new to this blog, and found this thread because I am having to replace my tracks due to divets that have developed, causing great difficulty. I really like the idea of the metal tracks; however, my Grace Inspira frame carriage rides on one flat track and one "A" shaped track where the rollers rest at 45degrees on the track. When I replace all, it is 3 tracks rather than 2 because of this feature. This, I think , would prevent me from using the metal rods unless I could get ones that were only half-circle shaped. Id be interested to know if anyone has used this method with an Inspira frame and carriage. Thanks.