It is flat. I think an mob would be a waste of time unless you are prepared to travel a fair bit.

A train out to Thetford Forest in Norfolk might be the go. There is a bike store that does MTB hire in the forest visitor centre.

It is flat, but the trails have flow.

Hire a roadie, ride to a destination with the prevailing wind, have lunch then take the train back; the ride speed will be a big thrill.

Depending on your travel options when you are here, there is Bike Art at Thetford forest at the High Lodge visitor centre. The main guy there is a bit spikey to deal with, but they have a half decent selection of bikes and there are a couple of waymarked trails you can easily follow. There are plenty of off piste stuff to, but easier to find with someone,e to guide you round.

There is Grafham Cycling (part of the Rutland Cycling shop) at Grafham water. It’s an OK loop, but nothing particularly exciting. It’s around 8 miles round.

A bit further afield is Rutland Cycling at Rutland Water. There’s 2 shops, both which hire bikes; one at Normanton and one at Whitwell. The Whitwell shop is bigger (the Normanton is a Giant concept store). The loop is nice and scenic. You can do a loop without the peninsula which is about 17 miles or with the peninsula it’s 23 miles or so.

Alternatively, you might be able to hire a bike in Cambridge and have a potter about. There’s a shop called Ben Haywards in the centre of town. I’m not sure if they will hire bikes, but if not they’ll probably know who will.

🙂 If we are going to be pedantic about it, I’m not _very_ wrong, just not as precise as I could have been. Indeed there are lovely non-pine bits in the forest. Though not all of them are deciduous – there is even a glade of eucalypts IIRC.