Hi Wirebrush, and please let me define what I mean about 'flex'...yes, if you wiggle the bike, being that the support arms are flat steel, and are not reinforced from side to side, (no lift is...truly), then yes, the bike will move slightly. The flex you need to truly worry about, is the vertical plane, the lift plane. For if there is pogo-pogo 'flex' then the hydraulic lift and suspension parts can not support the weight of the load. In the lift plane, the aluminum frame piston, and flat re-bar strut supports have no problem, and when I lift, there is no bleed off for my lift duration.Thanks, @YamahaParExcellence for the input. That the HF aluminum unit lifts your SVTC without issues is encouraging. I did use it to lift up my SxS 4-wheeler (est. 1100 lbs.) yesterday and it did pretty well. I wiggled the SxS while elevated and there was definitely some flex in the lift. I was prepared for a cautious valve release for descent, based upon past experience. The Eluder GT is some 200 lbs. lighter so I will probably try lifting that before I give up on the HF aluminum lift but I want to have a helper on hand before I try.
All my prior lifts could be moved laterally, as there is no lift I know of out there, that has for instance side bar supports that are round, and therefore, would have some kind of anti-lateral resistance to movement on the horizontal plane. Also, for oil changes, that don't much move the bike on the lateral or vertical plane...the lift by itself (any lift by itself) is good without further support, BUT...if you are going to do physical repairs, re and re tires, rims, blah, blah...I always put two supports (axle supports with a flat wood top) under and just touching my front and back tire, so when I take off, or put on the rims, or parts...or torqueing fitments, the bike will NOT pogo front to back, back to front, and be very stable...with the lift only truly responsible for the lifting of the bike off of the ground.
If you are going to think about following my advise to add support to the front and the back of the bike...with T-supports or whatever else you make... I most HIGHLY suggest, that you attach a printed WARNING Card that you can clip onto the top of the lift handle (pump handle) to warn you that you have tire supports under your tires. Why? Because we as human beings, have, can, and will, 'while seeing' the supports there, under the tires, can when we set out mind to finishing the job...be 'mentally blind' to them. Of course, if you start dropping the bike with the tire supports in place, the bike will be suspended in the air, the lift going down and the bike will tumble towards you or away. Make your self-warning to remove BOTH tire supports BEFORE you descend, and this will never happen to you! Also, I suggest that you spray paint your supports (most likely home-made from two x fours) in WARNING PINK OR YELLOW paint, just as another safety layer of being 'in your face' visible and to the at-point conscious mind.
Personally, I have not, and would never not only use the few square inches of support from any motorcycle or ATV lift, that has a balance point in the MIDDLE of the lateral weight...to totally support the bike, when being touched and handled. You will always have FULRCUM effect in the lateral plane...and THAT is where bikes can and will tip over, or pitch forward or backward off of the lift support pads(bars). My 84 cents...lol! Be safe...and happy 'landings'; with your motorcycle!