If your wife's Spyder doesn't have the '
vibration issues' that could be felt at speeds from about 40mph on up that resulted in the development & installing of the '
belt vibration dampeners' (No, they
ARE NOT actually '
Belt Tensioners'!! :lecturef_smilie:

) then
NO, her Spyder doesn't need one
and in the interests of belt longevity and reliability, arguably should NOT have one!! :thumbup:
These vibration dampers are small, spring-loaded rollers that (usually) run on the top of the belt, gently adding pressure to the belt in order to stop the harmonic vibrations in that section of belt that on some Spyders, can be transmitted into the rest of the bike and felt as annoying vibrations, sometimes even being heard as odd vibration type noises. That's all fine & dandy, IF you need it, but if it's NOT needed, you save your belt from having the extra wear of a roller spinning away on top of it, pressuring it more than is ideal, and basically, adding to the belt wear. And then there's the issue of that tiny little roller spinning away madly
ALL THE TIME!! :shocked: Plus, there's not much of an opportunity for a serviceable bearing in that tiny roller; nor is there scope for much in-built/inherent lubrication in the bearing, so the life of those rollers
IS NOT NECESSARILY ALL THAT GREAT!! And guess what often gets taken out pretty much immediately that roller fails?! That's not even considering the extensive/expensive panel &/or other damage that can (& does) occur when the belt disintegrates down the middle at speed, keeping some parts entire while the others thrash around like carbon-fibre whips, flailing away at and beating everything within reach, damaging everything they touch.
So if her bike doesn't already have one, and it also doesn't have the exceedingly annoying belt harmonic vibrations at speeds above about 40 mph, then I'd suggest you don't really need one and could easily have yourself the bother of getting & installing one, save the $$, & save her the potential trauma if/when it fails & takes the belt out! :thumbup:
If you do find out that her Spyder has one, then make sure it's one of the better-quality a/mkt units, like that from Lamonster (ie. Not the OEM POS!

) and then make
sure you check the spring, the roller, & the roller bearings regularly, replacing as often as necessary or every time you replace the rear tire, whichever comes first! :cheers: