2019 Rival 1 1/8 vs 1 1/4 Tubing


New member
I am interested in purchasing a 2019 Ultramax Rival but one thing I hope to shed some light on is the 1 1/4 vs 1 1/8 tubing what does that do to the chassis? I will be running on a 1/7 mile dirt track with no banking and not much grip. Next season i will be running a small block open motor, i usually weigh in around 390 lbs, if anybody can help me understand the tubing variances and how that changes the chassis. Thanks for your time to read.

alvin l nunley

Site Supporter
Tubing stiffness squares with the diameter difference. A 1 1/4 frame is a lot stiffer than a 1 1/8 frame. At your weight, that could be beneficial. No way to really tell other than with somebody else's experience. 1 1/8 could be better at your weight and more stiffness would just hurt. And of course I'm talking with the understanding they both have the same wall thickness. Stiffness is linear with changes in wall thickness. If the 1 1/4 frame had a thinner wall, it would be slightly less stiff. Back in the 80s, I had the tubes bent for a 1 3/8 .065 wall tubing frame. Never finished it.
I believe the tubing thickness is different from big to small. I could be wrong though. Most I know running open small block stuff are on big tube.


Im dumb, but Ill bet the 1-1/8 chassis is more forgiving and the 1-1/4 chassis is faster when setup. I have learned most don't hit the setup most of the time. We all get close most of the time. Id call the manufacturer and ask questions, they may ask you some questions to give good answers. Good Luck.