The quality of the broadcast on ITV4 was awful, so pixelated and grainy you could barely make out the text, they must give almost no bandwidth to that channel, I hope the Tour is better. When the grande departe was in the UK the stages were on ITV HD and it was so good, then the rest of the Tour was grainy as hell, you might as well be watching a dodgy stream.
It varied day to day (the weekend live broadcasts were worse, even ignoring the transmission faults on Sunday), with Freesat usually better.
itv4 shares 10758 V on Freesat with 7 others: itv2, citv (closes at 7pm which is partly why highlights were sharper), itvBe and 4 copies of itv1 (all the time, thanks to the unique way in which most Sky receivers suck) in 18.3Mb/s -
http://www.lyngsat.com/Astra-2E.html
On Freeview, it shares COM6 with 12 TV channels and 18 others in 27.1Mb/s -
http://www.ukfree.tv/article/1107051058/Freeview_modes
So there's roughly 2.2875Mb/s average on Freesat for live and probably more in the evenings, while Freeview might be 2.085Mb/s less whatever the radio/data channels use... but I suspect they're all using statistical multiplexing so this will vary depending on who pays what and how data-intensive the sharing channels are being at the same time. They've refused to say for sure before. For example, on Freeview it looks like BT Sport were showing live swimming from the European Games on Saturday, which I think takes quite a high bitrate to do well, whereas earlier in the week they were showing less intensive things, like biographies of football managers.
I've also seen comments claiming that Freeview resolution is higher, which I think would mean more artefacts if the bitrate isn't correspondingly higher too... which it isn't.
http://www.ukfree.tv/article/1107051651/ITV4_bitrates_an_answer from 2010 makes me think this isn't a new problem.
(Edited to fix a maths error and tidy up some explanations.)