On the inside of the non drive side seatstay on a 6-ish year old Trek 7500 hybrid are 2 bottle cage sized bolts quite close together. There's nothing on the opposite stay.
Like this:
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What are they for then? Any ideas? 🙂
Stabiliser for an unbalanced Aussie?
Dynamo
Dynamo
Really? 🙂
a very small water bottle?
Stop pissing about on STW and get back to work!
[quote=PeterPoddy ]Dynamo
Really?
I'm thinking something lke this...
[img] 
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..though that only has one mounting bolt.
rocket launcher?
Non-UCI-legal fareing?
Caravan?
Falconry Perch?
Can't tell how high up the stay they are. If they are near the hub could they be for a coaster brake arm? Does look a bit high for that and not likely on a geared hybrid, more likely on a cruiser or town bike.
is it to hang pictures from?
Dynamo. There's a bracket that bolts to that, that takes the standard single mounting bolt for a dynamo.