I would do some research on that model. I read a lot about benders, and see a lot of complaints from people that own it.
Any reason you want that model?
I would say the model 3 is probably one of the more popular ones(if not the most popular) and would easily do want you want for a lot less money.
The rule of thumb is 3 to 3-1/2 times the tube diameter=bend radius. I think 4.5 is the most common for 1-1/4.If you are going to build by plans,find out what the plans call for.
HTH,good luck.
BTW...you could try my design...
http://www.offroadfabnet.com/forums/sho ... php?t=8830" .".." .".. muhahahah!
For those that don't want to read through it all, it will bend the tubing as fast as you can turn the wheel.