I bought this (and the "front" boss cover) to adapt my downtube shifters onto a pair of Paul Thumbies. The problem was that downtube shifters come with rounded boss covers, which allow them to fit against the rounded frame of the bike. (Thought I'd mention that since it wasn't readily apparent to me.) Paul Thumbies are designed to work straightaway with bar-end shifters only because bar-end shifters come with flat boss covers, like these.
Verdict? They work. They're of the same diameter as the rounded boss covers, so they fit snugly and perfectly to my Shimano downtube shifters (that came on my Bianchi Campione). And they also fit the Paul Thumbies with very little wiggle (the wiggle should be a non-issue when finally tightened).
One more thing: there are slight (in my opinion) cosmetic differences between the front and rear boss covers, the most significant of which is the height or thickness of the piece. The rear is shorter by about 1.5 mm; the rear is about 5 mm tall, and the front boss cover about 6.5 mm. I bought two because I thought there would be functional differences for the rear and front derailleur shifters, but there aren't any differences. As I like thinner better, if I could redo this purchase, I'd have bought two rear boss covers for both shifters.
| Item Package Dimensions L x W x H | 9.5 x 5 x 1 inches |
|---|---|
| Package Weight | 0.53 Pounds |
| Item Dimensions LxWxH | 1 x 1 x 1 inches |
| Brand Name | SHIMANO |
| Number of Items | 1 |
| Manufacturer | Shimano |
| Part Number | Y64343010 |
| Sport Type | Cycling |
