Gittreville Grand Prix Builder’s Guidelines
Prepared for: Cyclekart makers interested in entering The Gittreville Grand Prix and related events.
Prepared by: The Constructors Committee
Guidelines first published in 2009. This is the Eleventh Edition. Published December 2020.
All entries must have a chassis plate identifying the inspiration car, the builder and the chassis number.
All entries must run with legible racing numbers.
Good humor and fun.
The eligible period for inspiration cars is the “Vintage Period”. Admittedly, this is a supremely vague designation! The VSCC (Vintage Sports Car Club), has defined the vintage period (since its founding in 1934) as ending December 31st 1930. The VSCC was founded on the premise that the “proper” vintage car building era ended under the pressure of mass production. The modern VSCC Club retains this strict definition of “vintage” but, as a club, also embraces post-vintage “thoroughbreds” of the period 1931 – 1940 and earlier Edwardian cars. The club even accepts exemplary, hand-built post-war cars. The common link is the spirit of adventurous motoring. The VSCC, more than any other collector car club, believes in driving: track racing, speed events, hill climbs, muddy trials and driving tests. It is our goal to be something very much like the VSCC (albeit with our cheap, home-made cars!)
Our desire is that the cars participating in the Gittreville Grand Prix generally “fit” with each other in scale, proportion, ability and spirit. We are certainly not looking for uniformity but we do want all the cars to emphasize the skinny wheel, bare knuckle, adventurous spirit of vintage motoring and to run with each other on roughly equal (fun) terms.
The Constructors Committee initially considered a very closely prescribed eligible period and draconian rules covering specific components in an effort to ensure a good fit and an even field. In the end, we have realized that there can never be enough rules to absolutely ensure anything (least of all fun) and we’ve chosen instead to lead as best we can by example. Hopefully, we can inspire all interested builders and drivers to work toward the most important goal of good humor and fun.
These builder’s guidelines are not meant to cover event rules or driving etiquette but it is worth noting briefly that we are “serious” about our fun. All drivers are expected to maintain a genial attitude at all times. No exceptions. Drivers are expected to participate in course walks before events and to volunteer their help in all activities.
All events are put on collectively, no one should show up expecting to just “race”.
GRAND PRIX FORMULA
What follows is an outline of intentions and suggestions with a few absolute rules.
From time to time, we will reference the “classic formula” in our discussion. When we do so, we are referring to the Stevenson’s cyclekart formula. Our guidelines are developed from those. Our approach is a bit looser since we (mostly) aren’t fiberglass people and are more open to complex fabricated metal solutions.
Over time our cars grew more disparate in performance, technical level, size, weight, etc.; especially cars from the later part of the permissible era and cars inspired by “specials”. In 2017 we added some language to the guidelines to help address the issue and to establish handicaps for events. Our system was too complex and in spite of our good intentions, proved very subjective. We believe an opinion based approach is actually the most effective and we have since removed that language from the Guidelines.
As an informal group, the biggest pressure to “sort things out” has come at Tieton. It is easy with the familiar Gittreville core to make sure the play groups are appropriate. This is true whether “events” are themed by era, performance capabilities, driver competitiveness or otherwise. We just “know”. We have decided it is better to leave it there and not try to put numbers on things.
Where before we had three technical classes, these guidelines will describe only our Grand Prix Class (unchanged). The guidelines will however, continue to include instructive references to the two technical classes we have abandoned. Those classes represented the best of what we believe the true spirit to be (our Voiturette Class) and a generous inclusion of a less pure fringe (our Formula Libre).
You don’t have to agree! These are Gittreville’s guidelines and apply only to our events. In no way should our guidelines be presumed to have any authority beyond that. Only at Gittreville events do they carry any weight.
Our ideals emphasize the magic of inspiration cars and the spirit of camaraderie.
We all love to race but our approach is to do that within an absurd construct that to a large extent pushes technical advantage as far off the table as we can get it.
Bottom line, build a reasonable car and help organize/ host and you can expect to participate.
OUTLINE of THE GUIDELINES
- Grand Prix Class
- former Voiturette Class – clues to what we consider to be aspirational
- former Formula Libre – clues to things to avoid, or at least pursue with open eyes
- DIMENSIONS AND WEIGHT includes WHEELS AND TIRES
- Thoroughbred exception
- Edwardian exception
- Veteran exception
- Hot Rod exception
- Three Wheel exception
- MOTOR includes Stage One Guidelines
- CHASSIS / BODYWORK
- CHASSIS TAG
- ELECTRIC CLASS
- All cars must have an indelible metal chassis tag and legible racing numbers.
All cars must have a clearly identified inspiration car from the vintage era, very loosely defined as ending in 1940. It is expected that the built cyclekart be generally guided by its inspiration car and that car’s racing era. We do not expect slavish replicas or fastidious historical accuracy but we do want the inspiration of the period to come through. Our cars are caricatures. As with a good caricature, the essential personality of the inspiration car should be evident.
GRAND PRIX CLASS
- 39” absolute maximum track. No exceptions (in the sense that wider track is penalized)
- 17” Ø wheels, 160 max. width rims, 2.75 max. width tires. Front and rear rims must be the same diameter.
- 275 lbs maximum vehicle weight.
- Honda GX200 (or clone) motor. “Stage 1” motor modifications encouraged but stock motors are also absolutely fine.
- $2500 maximum expenditure for materials, components and parts made by others.
VOITURETTE CLASS (our former aspirational class, included here for guidance only)
- 39” absolute maximum track. No exceptions.
- 17” Ø wheels, 140 max. width rims, 2.50 max. width tires. Front and rear rims must be the same diameter. No exceptions.
- 225 lbs absolute maximum vehicle weight. No exceptions
- More-or-less stock motors encouraged. Stage 1 motors may be run (inexpensive “box stock” motors are already modified and as the primary objective of this class is to keep things simple and cheap there is no reason to exclude them.)
- One wheel drive. No exceptions in track events.
- $2000 absolute maximum expenditure for materials, components and parts made by others.
FORMULA LIBRE (our formerly easily excluded class)
- This class is intended to catch the cars modestly exceeding restrictions in the Grand Prix class that are still deemed to “fit” with the other cars. Excesses might be in dimensions or weight or it might be in more exotic engine modifications or simply in apparent cost.
The effect of slipping out of the GP class into Formula Libre may not be any more severe than the application of a discretionary handicap in a given event. Formula Libre has been created with this intent.
Dimensions and weight
We have decided not to be particularly restrictive on length in order to allow for some of the very long cars from the early part of the period. There are inherent drawbacks in having an excessively long car on our courses so we feel length will be effectively self-policed.
In contrast, we have set 39” as the ABSOLUTE MAXIMUM track (front or rear). We are defining track as measured from outside tire wall to outside tire wall on the contact side of the wheel (note: not measuring to the edge of the contact patch). Wider tracks and fatter tires have performance potentials that could easily make racing too serious and quickly spoil the fun. We aren’t trying to build 1 1/2 litre F1 cars from the early ‘60s! Wide tracks also create dangerous congestion on tight courses.
We have debated and wrestled with self-doubt but have stuck with the classic 17” wheel formula. The preferred rim size is 17” Ø with a few special exceptions outlined below. Maximum rim width is 160 and the maximum tire width is 2.75. We fully understanding that 17” wheels are the most difficult size to find. Sorry about that — we feel they are correct.
Important exceptions and associated handicaps:
Thoroughbred exception – 16” wheels will be allowed where they are in proportion with the inspiration car (probably from the later 1930’s). 16” Ø wheels will be handicapped by restricting the allowed engine to one class smaller, the GX160 – or – to running with one wheel drive. Up to 3.00” tires will be permitted, again if in proportion, but cars using those wider tires will also be restricted to the GX160 engine (or 1WD). The handicap is the same for smaller and for wider. Both offer the promise of superior performance so we are offsetting the presumed better handling and extra traction with the restrictions.
Edwardian exception – 18” Ø wheels will be handicapped in a different way. Whereas we feel 16 x 3.00 wheels would look absolutely correct on a car inspired by a car from the late ‘30s (and the superior performance that implies), 18” wheels will more likely suit the larger, heavier cars of the Edwardian period. As we are following a methodology of either wheel size or tire width invoking a handicap, it is assumed any variation in wheel size will probably be associated with wider tires. The handicap for 18” Ø wheels will be a minimum wheel base of 74” and the driver may not sit lower than 4” (seat compressed) above the axle (wheel center) line. Only a true Edwardian car is going to look right with a wheelbase this long and big balloon tires (we are holding fast to the 39” maximum track). The wheelbase and higher pre-WWI look will force the real handicap: extra weight. Of course, long pre-war cars are not precluded from using 17” Ø wheels and sitting lower (for example, Bedelia and GN). If an Edwardian car has a shorter wheelbase (than 74”) or the driver sits lower than 4” above the wheel center the car must use 17” wheels and maximum 2.75 tires.
Veteran exception – No minimum wheelbase for these very early cars but the driver must sit at least 8” above the wheel center to utilize 18” Ø wheels and/ or 3.0 tires. The handicap is, of course, the extremely high seating position.
Hot Rod exception – We’ve always said that our rules are dynamic and will evolve according to circumstance. This exception is, so far, unused. Hot Rods and Lake Racers must have different diameter wheels front to back wheels with fronts as small as 16” Ø and rears as big as 18” Ø. The fronts MUST be narrower than the rears and this exception is only permitted if the driver sits no lower than 1” above the rear axle centerline. Further, this exception is only valid if the inspiration car is a true American Hot Rod. No real handicap – we think this is pretty cool.
Three wheel exception – Three wheel cars are sensibly permitted to use wider wheels and tires on a single rear wheel than normally permitted.
Our original weight limit was raised from 250 lbs to 275 lbs early in the evolution of the guidelines (the former Edwardian exception). In spite of the raised GP Class limit, 240 to 250 lbs remains a good target. This is the weight of the car without a driver. We are defining this weight as including oil and “some” gas in the tank. The weight limit does not include things shown in Concours but normally taken off for spirited driving: fake headlights, engine covers, decorative fenders, etc.. We feel the weight limit is a good idea. The limit forces hard choices to be made on what components and features can be incorporated into the car. Some of the inevitable compromises will dampen performance but, more importantly, they will also help moderate the budget and control building time. Keeping things lighter and simpler keeps it fun.
There is no minimum weight. The extremely high proportional weight of the driver will offset any serious performance gains from a featherweight car.
SUMMARY of dimensional guidelines
- Overall length: vague limit implied by proportion, 98” as a very softly suggested maximum.
- Wheelbase: “in proportion”, around 69” suggested – inspiration car is the best guide. Width (at track): ABSOLUTE MAXIMUM of 39” – around 37” is generally suggested.
- Weight: maximum of 275 lbs.
We have decided to stick with the classic formula engine, the Honda GX200 utility motor. The exception is when the Honda GX160 is mandated by the Thoroughbred handicap. Both of these units are outstanding marvels of economical, mass production engineering.
In contrast to the classic formula, we will allow (actually encourage) “stage 1” modifications in our GRAND PRIX CLASS. From experience, we feel “stage 1” motors enhance the drivability and fun factor significantly over stock motors without creating excessive performance or incurring unreasonable costs. Best of all, “stage 1” motors offer more things to tinker with! Generally “stage 1” includes removal of the governor, heavier valve springs, advanced timing, lightweight fan, re-jetted carburetor (often removal of the choke), disabling the low oil sensor, free breathing air filter and free flowing exhaust. Sometimes this includes removal of the re-coil starter. Doing that has proved painfully inconvenient at Gittreville so consider the tradeoffs before you remove the pull start. There is nothing quite like finding yourself — with the motor off — several miles away from your starter…
We have previously defined “stage 1” modifications as N-R Racing has defined them but found that method led to a wandering “spec list”. Further, “box stock” motors have inconsistent modifications already applied to them. So, see STAGE ONE SPECIFICATION RESTRICTIONS below.
Other makes of engine, B&S, Tecumseh, Robin, Predator, etc. are also fine.
The spirit of the rule is a nominal 6.5HP utility motor. We will accept any utility motor under (or around) 200cc displacement for the GX200 class and any motor under 165cc for the GX160 class. Purpose-built racing go-kart engines are not in the spirit of our formula. Engines must run on “regular” pump petrol without octane boosters or any other blends. The later point excludes two-stroke motors.
Important Expedition exception – Engines may not be modified except for exhaust. Cars intending to run Expedition events may not have governor removed or any changes made to carburetor/intake. Engines must maintain emissions standards. If exhaust is re-routed (which is permitted) it must be suitably silenced and must include a spark-arrestor. Flywheel may be changed to incorporate charging coils to run lights.
STAGE ONE SPECIFICATION RESTRICTIONS
- No change to compression ratio either through changing the head (GX160 on GX200 as example) or by milling. We won’t be able to catch a thinner head gasket so that is a loophole for interested builders to exploit. Event organizers may require all cars to use communal “regular” gas.
- Stock valves, cranks, rods, pistons, etc. must be retained. The spirit of these restrictions should be clear.
- Only the carburetor type delivered on the engine for utility use may be used, generally this means Keihin or Keihin clones. Mikuni, Walbro, etc., excluded. Maximum permitted bore is 0.625”. This will be checked by a no-go gauge. No restriction on re-jetting or emulsion tubes – builders are free to create trouble for themselves!
- Valve spring stiffness is up to the builder. As with jets, more isn’t always better. There is no realistic opportunity for engines on our cars to run at extraordinary racing go-kart revs and the stiffest valve springs are excessive (and will contribute only to additional cam wear.) No after-market rockers are permitted. No oversize valves, etc.
- Stock cams must be retained. Even mild re-grind cams will trigger a move to Formula Libre. Modified cams are easy to hear and the builder may be asked to sit in “the comfy chair” to answer some questions.
- There are no restrictions on changing the flywheel. Clone motors should have a billet flywheel fitted if the governor is removed. Smaller fans may be used on Honda cast iron flywheels. Timing is up to the builder.
- No restrictions on headers so long as the header has a muffler. Mufflers are absolutely required.
It is worth noting that a well-cared for engine running a stock bore carb with a very modest jet proved itself to be virtually indistinguishable from cars with bored carbs and monster jets. Even bone-stock governed motors perform admirably. Keeping things simple is generally a wise course (but do disable the oil sensor so the car doesn’t cut out on corners)
Our rules don’t require fuel pumps (or forbid them) and leaves the gas tank location open. Doing just the basic engine mods (short of Stage 1) adds almost all the performance gained by more sophisticated engine modifications.
SUMMARY of engine guidelines
- Engine: single cylinder utility motor; Honda GX200 or GX160 (if handicapped suggested). So called “Stage 1” modifications encouraged in GRAND PRIX CLASS, minimal modifications in VOITURETTE CLASS. Cost limits realistically preclude more.
- Motors must be muffled. “Stock”, B&S or RLV type muffler at a minimum. No straight pipes – our tracks have neighbors!
Experience has shown that a variable ratio belt drive is the most effective transmission. We are not banning go-kart type simple centrifugal clutches but strongly advise against them in our driving conditions. So far they have been frustrating failures. We recommend the Comet TAV-2 unit or equivalents for simplicity and dependability. For a little better performance, symmetric belt drives —MaxTorque, Comet Series 20 — are a good option. The symmetric drives require jack shafts so they are more complex. Both 6” and 7” drivens are permitted. Final drive is typically #35 or #41 chain but #40 chain, other chains or even belt drive are not excluded.
We decided to not ban final drive differentials. We have found that these enhance drivability tremendously. Differential units may be challenging to fit in the budget and track restriction might prove problematic, but they are not otherwise ruled out. The classic cyclekart formula advocates one wheel drive. Our committee does not entirely agree. Solid rear axle, differential unit or one-wheel drive are all allowed in the GRAND PRIX CLASS.
SUMMARY of drive guidelines
- Clutch/ transmission: Comet TAV-2 (or equivalent) recommended.
Our first car tested both drum and disk brakes. The classic formula calls for a disk brake. Our committee encouraged drum brakes as more in the spirit of the period until we suffered repeated (sometimes alarming) issues with brake fade. One of our cars tried band brakes (a pre-WWI anachronism) and after some fiddling got a pair of these to work almost as effectively as a single drum. It is not our intent to make anyone feel uncomfortable (unsafe) so the committee has decided to leave brake systems open.
Important Expedition exception – Expedition class cars must have two brakes and one of those must be able to function as a locking parking brake.
SUMMARY of brakes
- Braking systems: you must have a functional brake but other than that, details are open. Hand, foot, cable, rod, drum, disk, band – all are permitted. While not yet mandatory, having a back-up brake is a very good idea.
Front suspension schemes should follow the inspiration car. In our period this is usually a beam axle on semi-elliptic springs. The classic formula calls for 2’ buggy seat leaf springs and typically this is the right choice. Lighter cars from the period often have 1/4 elliptic schemes. Almost all cars in the period use beam axles. A handful of potential inspiration cars have coil springs and independent front suspension through a sliding pillar arrangement (Morgan and Lancia are most notable examples). Period, friction type dampers are encouraged. Front suspension is absolutely critical to success on our bumpy tracks. Without supple front suspension, steering is severely compromised because the wheels don’t make contact with the ground often enough!
The classic formula calls for no rear suspension. We are more open. While the cars work reasonably well without any rear suspension, they seem to work just a little better with some rear suspension. We have tried a limited travel 1/4 elliptic scheme that works well and we have tried a fully functional, longer travel rear suspension enabled through the use of a sub-frame for the engine/drive unit. The tradeoffs for rear suspension are weight, cost and complexity. Chain alignment is the critical issue.
SUMMARY of suspension guidelines
- Front suspension: following the inspiration car, generally a semi-elliptically sprung beam axle.
- Rear suspension: none or following the inspiration car. None is a sensible choice.
Builders and all drivers must understand that what we are doing is inherently unsafe! These are fragile, unstable, dangerous little machines – precisely why they are so much fun. We expect builders to take care that they are not creating a reckless menace. Beyond that, we are children of John Stuart Mill.
SUMMARY of safety
- Cyclekarts are unsafe
- Readily accessible and functional “KILL” switch is required. No exceptions.
The classic formula calls for a plywood “monocoque” covered in foam then fiberglas with chassis rails (steel tubes) attached to the sides of the plywood box in order to mount the front suspension and rear axle. The committee sees the simple merits of this scheme and recommends it enthusiastically for the VOITURETTE CLASS but does not want to exclude doing things better and more in the spirit of the times. Our approaches so far have mostly utilized ladder type chassis with built up bodywork added. There are a handful of monocoques in our period (Lancia and Voisin as notable examples) but generally, bodywork sits on a ladder chassis. Bodies of wood or metal framed with a wood or metal skin on the framework. “Fabric” bodies, very popular in our period, use fabric as the finish layer over wood – much as one of our cars uses Sintra over wood. Our committee’s bias is clearly toward formed metal and we’ve decided not to put any rules in its way!
Most important, for both the chassis and the bodywork, is to be guided by the inspiration car. Our scoring system balances race and test results with subjective, period appropriate judging in the Concours d’Elegance. The fastest car may not win the overall prize.
SUMMARY of chassis/ bodywork
- Chassis: technique open; a box steel ladder type chassis generally encouraged.
- Bodywork: technique open; emphasis on in-the-spirit-of-the-period.
Controlling cost is a quaint thought we take seriously. Many builders do go over the limit. Others are massively under. We don’t want to pretend to police this. In blatant cases or after good sportsmanlike admission, a car may be re-classed as Formula Libre at the discretion of the event organizer solely on the basis of perceived cost. Scrounging and adaptive reuse is fun! Builders will do well not to miss out on that aspect of building cyclekarts.
Cars are not allowed to race or be judged without a chassis tag. At the minimum, this tag should declare the inspiration car, the builder and the chassis number. Chassis numbers are assigned by the Constructor’s Committee in sequential order of substantial project progress. Let us know what you are planning to build. Give us a provisional spec. — wheels, general dimensions, drive scheme, etc.. At your first Gittreville event we will have a look at your build and typically assign a you a chassis number. We will have a letter punch set for you to add the number to your chassis tag or you may engrave it or otherwise permanently mark it.
Racing numbers are chosen by the builder but are subject to availability. Number 1 is reserved for prior year champions. Other numbers are assigned (permanently) on a first come – first choice basis.
The committee is offering suggested guidelines, we will not aggressively enforce nit-picky rules. We play on an honor system.
We will not do forensic accounting to verify that the budget is not exceeded. However, the committee members know very well what things cost. Distrust of whether a car is “on budget” or not may effect Concours scores. We know from experience that a car that does not incorporate salvaged materials and found objects is not likely to be “on budget”.
We will leave the possibility of disqualification or application of competitive handicaps to cars that appear to have an “unfair advantage” based on blatant bending of the rules or grossly overrunning the budget allowance to the sole discretion of the event organizers. The Race Marshal will have authority to impose race-day handicaps unrelated to this set of builder’s guidelines. Handicaps are intended to level the field and may be either beneficial or punitive. They may be utterly nonsensical. Some drivers may be required to wear a flower on their lapel (a flower they might have to first pick before they can start). It is assumed that no handicaps will be so severe that they dramatically affect the results. Handicaps are like stage 1 engines – more to fiddle with! Don’t take this too seriously.
New with the 2017 Guidelines and continuing now: chassis numbers must be maintained in “good standing”. This requires specifications are kept up to date and a dozen or so images of the car are provided to the builder’s committee. Send both to firstname.lastname@example.org.
Derelict cars or cars that change hands will lose their running numbers.
The constructors committee is available for advice on any aspect of car building. We are very open with information and more than willing to share our experiences to date. Committee members have made terrible mistakes they hope to help others avoid. You will find that the committee is especially free with its opinions…
Membership in the constructor’s committee is conditional on three things.
- Experience building and driving a car with an easygoing spirit that promotes the S.C.C.A. objectives.
- Good faith compliance with the Builder’s Guidelines as the committee maintains them.
- Willingness to share information. We are doing this for fun, not for cutthroat competition.
The constructor’s committee exists to help all interested builders complete their projects, thereby enabling an outstanding field of cars for The Gittreville Grand Prix and related events!
We are continuing to investigate electric alternatives as experimental extensions to the established class. Emphasis on exploration! Several years in and nothing is “final” yet.
E Classes offer the same opportunities to learn the fundamentals of vehicle dynamics, practical mechanical engineering and a wide variety of fabrication techniques as the gas cars. The E Classes add opportunities to address sustainability issues and to dabble in the dark arts (electronics). We imagine this will strike a chord with potential builders wrestling with social guilt.
Electric gets expensive quickly as performance improves. At all levels, batteries are heavy. Heavy batteries lead to heavy cars which leads away from the spirit of cyclekarts. We are hoping to find equivalence to what we expect as “normal” cyclekart performance and feel.
Costs are “very” roughly $1000 more than a Stage 1 (gas) car builds.
There is a low cost and lightweight general scheme suitable for our aspirational class but it is short on “sporting” performance. The Morgan F2 pursued this path and the result was the lightest and cheapest car to date (and super fun to drive.) Low weight is more important than ever but even so, the Morgan will certainly never be “race” competitive with more powerful cars. Super light electrics can be very competent in Driving Tests and other lower speed events. The compact electrical packages (for all electric cars) are easier to fit into vintage proportions offering benefits in Concours competitions (?) At the very least the electrics will make great parade cars and gracious guest drivers!
Our thoughts have coalesced around establishing three maximums: 48V (nominal), ~ 20AH and 5KW.
As noted above, the “big thing” is batteries. More than anything else, they define cost, weight and performance. 48 Volts (nominal) is internationally recognized as the prudent limit for human shock risk. Our skin is a decent insulator (barrier to shock) but what is under our skin is a tremendous conductor. CK accidents can easily break the skin. We are establishing 48V (nominal) as a firm maximum pack voltage for safety. This limit has the added benefit of helping control costs.
We are limiting battery capacity to 20 Amp/ Hours. This is primarily aimed at controlling cost but has the added benefits of holding weights down (a safety issue) and as a performance leveler. High power motors and robust controllers are tempting – limiting the battery packs creates a real limit to how much power can actually be exploited. The batteries will max out well before the motors will. The 20AH limit encourages a quest for efficiency vs power. Batteries are improving so rapidly that the builder can assume higher AH ratings will be embraced if the batteries are not too heavy as noted for safety and not too obviously expensive. (Note: battery technology is changing rapidly)
Very low cost is achievable using conventional (AGM – not wet) batteries and reasonable cost is still achievable with LiFe packs.
We are limiting motors to 5 Kilowatts (nominal industry standard ratings) again to control cost, weight and performance. We are feeling our way through the new electric technology. It is our hope that in time, we will move toward using lower rated, perhaps 3KW, motors as a better match for the battery pack limits.
Our present state of the art for motors is BLDC (DC three phase) with sine wave controllers. Contactors (main on/off switch relays) are recommended and may eventually become required.
In all classes, multiple motors are OK — example: one per wheel — but the motors will be cumulative with regard to power limits.
State of the art for affordable batteries is LiFePO4 with BMS or Lithium-Ion with battery management. These batteries are stabile (won’t explode, etc.) and have good life.
SUMMARY of E class
- 48V, 5KW, ~20AH.
- Lithium or conventional batteries. Li with a (critical) battery management systems is expensive but what ya’ gonna’ do? Enhanced nonspecific spend limit.
- 25# added to the weight limit so: ~ 300#.