nirakaro wrote:Ivor makes some valid points, but just as a counterbalance:
First long tour I did (and I'm certainly no marathon runner), I'd scarcely ridden a bike in the past four years. I did forty miles the first day, forty-five the second, and expected to be knackered on the third. I wasn't, and carried on doing three hundred miles a week for the next two months. That included crossing the Alps (1300m climb up the Simplon), and I didn't find that day more tiring than the others, as the five-hour climb was followed by virtually freewheeling twenty or thirty miles. Horses for courses I guess.
The passes from Austria to Italy (Brenner, Reschen) are quite low (~1500m), and virtually never close. I rode up to the Tauern rail tunnel at ~1200m on the 9th April last year and saw no snow at all. Or from France, the Lautaret and the Montgenevre, though higher, are major routes that are kept open except in the worst weather.
Continental hills are a lot gentler than English – and I suspect Welsh – hills. The slope is usually no more than 5-6%, and the amount you climb is pretty much the height you gain – you're not forever upping and downing like in British hills.
I agree that I'd want a tent, but we're all different; crossing the Alps only takes a day, so there's no need to camp at altitude, and I think the issue, given a good sleeping bag, will be rain rather than cold. And you can pretty much always find a room if necessary.
BTW I believe wild camping is prohibited in Germany and possibly Austria. You'd need to stay very much out of sight.
Cycling 40-50 miles a day is totally different trying to ride 90 miles a day. Not only is it a lot further but eating enough becomes critical and looking after your body. But I guess if the OP is into marathon running she is aware of fuelling her body and not cramping and bonking. Just because I ride a lot and run 5-6 miles most days there is no way I could compete as a runner nor would I start by running a marathon. I would probably start with much shorter distances.
Yes mountain passes or cols int he Alps tend to be more gradual in their ascent than some hills in the UK, but they can still be gradients of 8-10,12,15 even 18-20% and go on for a lot longer. The Brenner pass climbs to just over 1,300m in 32-33kms. The road up and down is literally a motorway. I think one of the Eurovelo routes goes up the Brenner pass and you ride away from the road on an old railway track. I rode it many years ago before the EV routes were conceived. If you want hard short very steep killer hills then ride in the foot hills of the Pyrenees in the Basque Country.
, the old road is there, well maintained and takes longer to gain the metres from the north. Can't see where you5 ride on an old railway track, the rail line is till there in use. 
