Reading this many may feel i am writing about Competition and competitive advantage.
I am not.
I am skimming over the history of vintage karting. it is a light version and is not 100% accurate maybe but it makes a simple point.
Early sidewinder frames were built to cool foreign motors nothing more.
the second generation sidewinders were purpose built to enhance track performance but aren't a huge advantage.
The early varients should be run with rears as a matter of policy.
If second gen sidewinders are at an event but lack grid numbers they too should be run with rears as long as they are equiped with square sided hard skinny tires.
on the straight axle sidewinder class, that class was supported a few years ago.
we had a bunch of them on the East coast and i ran with them.
these were mostly second generation straight axle sidewinders with relatively crude frames but equipped with movable fiberglass seats.
while they can be safely run with rear engined karts when equipped with square tires they do have a competitive advantage.
so we ran them as a separate grid in the so called straight axle sidewinder class which was very popular and fun class to run in at first.
sadly it was TRASHED by allowing sticky tires on the straight axles and then allowing y axle karts to run with them.
At first , The y-axles were grouped with the straights as they became legal vintage.
initially there weren't many y-axle years to chose from that were legal and that was thought to be a good idea.
Sadly it kinda killed the second gen sidewinder class.
While sticky tires can be run on the straight axle sidewinders the frame tuning is critical and driver skills need to be pretty high.
this is because the frame wasn't designed for sticky tires and they tend to bicycle when run wrong.
Meanwhile the y axle framed karts originally designed to run hard tires were far easier to retune to run sticky tires.
There are other advantages in their design that makes them far faster karts but it was mainly them being well able to run sticky tires .
it wasn't long before most of the drivers migrated to the y axle frames .
they handled better , ran faster and were able to sticky tires with little changes.
this was exactly what happened in karting history.
Originally american the sidewinders were created to get the foreign engines into the wind.
This had nothing to do with getting faster frames it was to allow using bigger and faster foreign motors.
The early sidewinders were just variants of a rear frame with steel framed seats on all models.
Steel framed seats are extremely hard to move to different positions.
as foreign motors became more popular karting started moving to more "foreign engine" classes.
This created a need for sidewinders and right about then enduros were gaining in popularity.
enduros are extremely hard to design as a rear engined karts so migrating to side mounted engines was a natural.
since american motors don't care where they are mounted manufacturers started building only sidewinders (cheaper).
Many realized sidewinder frames , when designed right , can be faster than rears and as time passed the rear era was ending.
The first gen sidewinders were simple variants of rears but that changed with the introduction of fiberglass seats
The second generation of sidewinders came with bolted in lighter fiberglass seats .
this allowed far easier changes to seat position and since driver wt. is the majority of a karts load .
Seat position movement is a HUGE advantage when a frame is being race tuned.
they also were set up with rear steer and front porches were added to many adding critical leg room.
Also in years past it was discovered that less metal welded to the frame tubes allowed alot more flex.
this was first noticed when in efforts to lighten frames seats and floor pans were replaced with aluminum rivited or bolted in to the frame.
because the frames could "flex" better when not constrained with welded in pans the karts also cornered better.
the final best example of this is the Fox kart frame which was purposely designed to have a floating seat.
the gk series 1600, that was never produced, had gone as far as to CUT the rear bumper to allow more flex.
The purpose built sidewinders carried all this knowledge so the floor pans were all inserts not welded and the seats were built out of flexable (comparatively) fiberglass.
But the biggest change was the seat being bolted in thus moving it in tiny increments became possible.
Also the rear bumpers were bolted in in many cases so they could "float".
These changes made for a faster frame but the new fangled fiberglass seat is key.
My new breed sidewinder is pretty good handler, but my cheetah which is a purpose built sidewinder is alot better handler.
the new breed Already had many of the "faster" design features , loose floor pan ,bolted rear bumper a somewhat looser seat attachment (bolted with tube clamps).
the frames both by margay are the same length, same width same spindles, same front axle brakes basically the same everything except the seat which is steel framed rigid (new breed) as opposed to flexy fiberglass (cheetah).
The foreign karts had been being built as sidewinders since the early sixties.
these karts had advanced to y style axles and american companies soon followed.
So the straight axle sidewinders purpose built lasted only a few years.
Concurrently the tires got stickier and frames were redesigned to handle the new compounds.
The motor mount was also changed from the axle bearing style to welded in the frame tubes which was a major drag reduction on the kart chassis.
Less drag = faster lap times.
anyway i got way off track here.
basically the straight axle PURPOSE built sidewinders only cover a few years.
They are stuck in kinda rare limbo as they are slightly faster than rears but slower than y axle sidewinders.
So what to do with them.
Over the years my personal experience is they should be run with narrow hard tires as they were designed for and run with the rear engined classes when there aren't enough for a grid.
This should go for any straight axle sidewinder.
The earliest sidewinders weren't purpose built and don't really have much if any competitive advantage.
The later purpose built ones are slightly better handlers but only in the hands of a good driver, good engine,good carb,good fuel and good luck.
You get the idea.
The MAIN REASON to put them in the rears is matching tire performance.
mixing hard with sticky tire compounds always has bad results possible.
Since we are out there to have fun and BE SAFE it makes zero sense to mix hard and soft grippy tires together.
This trend towards mixing soft and sticky tires at certain events must be stopped asap imho.
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Dave L.