It'll hurt, I can tell you.
This road is on the same hill as the largest one which I live on - Lansdown Hill. I include it to show the gradient. It's around 1 and a half miles long, although not continuous. I've hit 45mph down it.
This is one of the hills down from the University, this is actually the shallowest part and it's quite near the bottom (the canal bridge is just round the corner). The other two roads (North Road and Widcombe Hill) are steeper in places, a bit shorter but narrower and poorly lit. This one has all the buses on and most of the traffic (it's the only one signposted) , so I tend to avoid.