Swindon saw their unbeaten home run ended by Premiership leaders Somerset, who notched a 49-41 win at the Abbey on Thursday.
The CFS Filtration Robins found the absence of two riders, David Bellego and Zach Wajtknecht, too big of a hurdle to overcome as their top four were left with no support against a solid and in-form visiting side.
Tobiasz Musielak, Nick Morris, Troy Batchelor and Adam Ellis did all they could but their margin for error was very limited, with reserve duo Jack Smith and Ellis Perks suffering a series of falls and being unable to make an impression.
Musielak was outstanding and lowered the colours of World Champion Jason Doyle in Heat 5 as the Robins battled back from an early six-point deficit, having earlier combined with Ellis for a 5-1 in the third.
Swindon provided just one finisher in Heats 6 to 8 inclusive as Morris, Batchelor and Ellis all took wins but their reserve colleagues fell on each occasion.
They did get themselves level with a 4-2 in Heat 9 with Jack Holder splitting Musielak and Ellis, but disaster struck in the next when Morris crashed heavily on turn four when holding a clear lead.
Thankfully the Robins skipper was able to walk away, but it handed the advantage back to the Rebels as Aaron Summers and Richard Lawson recorded a damaging 5-1 in the re-run.
Doyle got the better of Batchelor in a fine early scrap to Heat 11, and with another ex-Robin Bradley Wilson-Dean rounding Perks for third, it put Swindon six down again.
Alun Rossiter introduced Morris as a tactical substitute in Heat 12 and he won the race after a tough first bend, but Ellis was kept in third place by impressive Rebels guest Tero Aarnio.
With a race advantage crucial, Batchelor threw everything at Doyle in Heat 13 but eventually came to grief the start of the last lap as the Rebels re-built their six-point lead.
And although Musielak won Heat 14, Aarnio and Lawson packed in for second and third places to seal the visitors’ win.
Doyle sat out Heat 15 but his side still notched a 4-2 through Holder and Lawson – the former inflicting the only defeat of the night on Musielak – to take maximum points from the meeting.
Rossiter said: “Every defeat is a tough one to take, but we had a four-man team tonight and we nearly pulled off a win against the top of the league side.
“No disrespect to the reserves, but the other four really rode their hearts out and unfortunately the track was catching a lot of people out, especially on the pits turn.
“Nick was leading Heat 10 when it caught him out, and I think that was the turning point in the meeting. But I certainly don’t blame him, he’s been good around here, and we all saw the effort that Troy put in during Heat 13.
“It’s a bitter pill to swallow with it being against Somerset, especially just before Cardiff this weekend, and we had a great crowd too, but we can only do what we can do, and we have to look to bounce back.”
Robins expect to have Bellego back for Monday’s match with Leicester, although Wajtknecht will still be out due to his compulsory concussion break, with Dimitri Berge booked to guest.
SWINDON 41: Tobiasz Musielak 13+1, Nick Morris 10, Adam Ellis 9, Troy Batchelor 7, Jack Smith 2, Ellis Perks 0, David Bellego r/r.
SOMERSET 49: Jason Doyle 11, Jack Holder 11, Tero Aarnio 10, Richard Lawson 7+2, Aaron Summers 4+1, Jake Allen 3+2, Bradley Wilson-Dean 3+1.