I have been hybridizing roses for 37 years now and I still say : "It's 99 percent luck and 1 percent planing.
It all depends what the parents of these 2 climbers are.
Most likely you will get 90 to 95 % climbers, or "ALL" ?

When I crossed the Cl. Sutters Gold with a HT many years ago all 4 seedlings came out as climbers.

You just have to try it.
Good luck George Mander

Here is a link that might be useful: Roses of Excellence

george...thank you...have you noticed a difference with hybridizing clinbing sports? it would seem to me that they may have a higher percentage of shrubs?? thanks again, donna

Hi Donna,
Since most seedlings from climbers do not bloom the first year, I have kept away from crossing them.

You will need lots of space in your yard to plant them and wait for the first blooms which sometimes takes 2 to 3 years.

When I crossed our native Rosa Nutkana with my Fl. 'Shades of Pink' I had 50 seedlings to plant along the fence and run out of space. Most took 3 to 4 years to show their first blooms and one even took 5 years.
As I am limited for space, I keep away from Climbers and species roses.
George