This comes as the search for Wayne Hammond, who was last seen in Clyde on Monday morning, entered its fourth day yesterday.
Police said on social media last night they wanted to speak to two cyclists seen near the Clyde Bridge on Monday.
"They're not under any suspicion, but we are hoping they may be able to help us with further details into Wayne's movements."
The male and female cyclist were in the carpark underneath the Clyde Bridge, at the start of the Clyde-to-Alexandra river track, between about 8.15am and 8.30am on Monday.
"If this was you, or you know who they might be, we're asking you to please get in touch."
A new image Mr Hammond taken from CCTV footage at his workplace - an Alexandra plumbing company - was also released yesterday and it is believed he was wearing similar clothing at the time of his disappearance.
Search efforts for Mr Hammond intensified on Wednesday when a team of four police divers began searching the Clutha River near the Clyde Bridge walking track.
A police spokeswoman said those efforts continued yesterday, the divers focusing their search on the river below the Clyde Dam.
Police and Mr Hammond's family had concerns for his wellbeing and called for help from the public to find him, she said.
Specifically, police would like to speak to anyone who was on the Clyde to Alexandra track between 7am and 9am and Monday.
Police also asked anyone who was boating in the area and might have seen something of interest to contact them.
