Thunderbike Rules - Base Rules
Below for review by everyone ahead of the Brands GP meeting on rules, the base Thunderbike Sport rules are below
BMCRC Thunderbike UK Championship Regulations 2013
All machines in these classes are restricted to a power-to-weight limit, and an overall maximum power limit, in order to promote close and fair competition. The power restrictions are measured at the rear wheel using BMCRC's scales and dyno, and are as follows :
Single Cylinder Thunderbikes (Tb.)..........1 SAE bhp 1.56 kg weight.
Please note the power to weight ratio applies to all machines.
The Rules & Technical specifications :
1. Race numbers and background colours:
1.1. Race numbers for this class must be Black on White background for Thunderbike
1.2. All machines must carry a sticker identifying their power to weight class.
2. Chassis :
2.1. Frame, engine cases, and cylinder heads must be from the same
2.2. Single cylinder motorcycles and accepted “technically interesting” motorcycles may use
2.3. Anything other than frame, crankcases, and cylinder heads may be modified or changed subject to:
2.3.1. Seat sub frames where fixed may be replaced by bolt on replaceable rear sub frames.
2.4. Hybrid bikes (Big engine, small frame) whose engine conforms to the rules stated may also be considered and approved on an individual basis by the series coordinator(s) and/or eligibility officer(s). In the case of hybrid bikes, 4 stroke engines must be mounted in a 4 stroke chassis. 2 Stroke engines mounted in a 2 Stroke chassis.
3. Wheels and tyres
3.1. Wheels may be replaced. Tyres can be treaded or slick. Rain tyres may be used.
4.1. Reducing engine size of machines from stock displacement to meet BMCRC Thunderbike class displacement limits is not allowed.
4.2. Crankcases may be strengthened.
4.3. Cylinder heads may be modified but must retain the original number of valves.
4.4. Engine displacement limits are absolute and are set as follows:
5. Electronic control systems
5.1. The use of electronic control systems to aid launch or traction are strictly forbidden.
5.2. Bikes are only permitted to have one loaded fuel map at any one time, and any bike found with multiple maps loaded in the software will be excluded. Any ‘On-the-fly’ switch-able map is strictly forbidden.
6.1. Throttle stops or cable adjustments must be fixed or secured in a manner that will prevent adjustment by the rider or crew without the use of tools prior to dyno testing.
6.2. Switches or other methods designed to affect horsepower readings during dyno testing are strictly prohibited.
6.3. Machines are restricted to the mounting and use of one ignition or engine management
7. Technical Inspection
7.1. The dyno operator, Technical Official or person appointed by the race or series organisers to ensure eligibility, may request removal of bodywork before, during or after dyno testing, and may request removal of other components for inspection.
7.2. Any machine not capable of post race dyno testing will be deemed to have failed the dyno
7.3. Machines will be run on the dyno until, in the opinion of the dyno operator the maximum
7.4. Machines will be selected at random by race officials to run on the dyno as soon as possible following the end of the race. Failure to report directly to the dyno when requested to do so after the end of a race will result in automatic disqualification.
7.5. All machines must have at least 1 spark plug lead or coil lead accessible to the Dyno
7.6. All machines will be weighed on the BMCRC Technical Officials own scales. They will be calibrated in house before each round and yearly as deemed necessary. They are definitive. (Circuit scales will only be used if the BMCRC scales are unavailable).
7.7. Machine test procedure will be as follows.
7.7.1. Machine(s) will be selected.
7.7.2. The machine will be weighed with fuel but without rider.
7.7.3. The machine will be Dyno tested and a Pass or fail given. No other information will be supplied.
7.8. Bikes which have been deemed to have failed the power to weight or technical rules may
Extreme Championship - Age eligibility rule clarification
All Extreme Championship riders - please take note
Currently the rules outlined on the detailed rules page state:
This series is for motorcycles manufactured more than 10 years ago as at the 1st. of March of the racing season or which comply with class engine limits, plus later hybrids and "specials" admitted at the BMCRC Eligibility Officer's discretion.
This is incorrect as the series was not aimed to have a rolling age cut off for homologated motorcycles
To be eligible the bike must be no newer than 2002 unless it is a model that was homologated before 2002 but continued past 2002 as a model for sale
That is to say that should a post 2002 model share its common components with the 2002 model it will be eligible under the legacy rule, i.e. no changes to the engine or chassis but may have a bodywork outline or colour change
The proof of eligibility lays with the competitor and approval should be sought from the Class Technical Officer that a post 2002 bike meets legacy rules before competing in the championship, as with all such matters the Class Technical Officers decision on eligibility will be final
There will be a corresponding update to the rules page shortly
2015 Race Dates Added
The countdown has begun, see the top banner for how little time you have to get ready
Please check the Races button to the left for all the dates
Changes for 2015 - Rain Lights
As you may or may not be aware the 2015 season sees the introduction of compulsory rain lights for use in WET races
The following advice was posted on the Bemsee site:
All motorcycles must have a functioning red light mounted at the rear of the machine to be used in rain or low visibility conditions as instructed by Race Control. The team must ensure that the light is switched on whenever a rain tyre is fitted on the motorcycle and/or when any practice or race is declared “wet” by Race Control.
Lights must comply with the following:
a) Lighting direction must be parallel to the machine centre line (motorcycle running direction), and clearly visible from the rear at least 15 degrees to both left and right sides of the machine centre line.
b) Mounted on the seat/rear bodywork approximately on the machine centre line, in a position approved by the Chief Technical Officer. In case of dispute over the mounting position or visibility, the decision of the Chief Technical Officer will be final.
c) Power output/luminosity equivalent to approximately: 10 – 15W (incandescent) 0.6 – 1.8 W (LED).
d) The switch must be accessible.
e) Rain light power supply may be separated from the motorcycle main wiring and battery.
If you have any questions please contact one of our Technical Reps
Neil Harris Motorcycles - ACU Discount
One of our former Extreme racers 'Neil Harris' is taking a year out of racing to focus on his business, although we will miss him on track he is currently offering clothing dicounts for ACU racers
If you go to his face book group:
Neil Harris Racers Clothing Discounts
You can apply to join the group and gain access to the discounted products- YOU MUST HOLD A VALID ACU LICENCE
Thanks for your support Neil and hope to see you out there next year
Tech Inspection - What they are inspecting on your Thunderbike!
Mark has kindly let me lift this from his motoforum post and publish here as a useful guide on what is checked when the tech officials scrutineer your bike, it makes for a useful read whether your new to the class or not, enjoy!
As there are so many rookies starting racing this season it can be a bit strange at your first meeting going to Tech Inspection, what to expect, what are we checking for? Well this is looking through my eyes at what i'm doing when looking at your bike, hopefully it gives a bit of insight to what we do.
Technical Inspection ……………what the hell am I doing?
Most officials have their own routine but basically all will check for the same items
From here I will check the front wheel, Calliper bolts tight? No visible signs of brake fluid leaking?
I will now check that the oil filter, sump bolt and filler cap has been lock wired (some bikes also have dip sticks this also has to be wired) any engine breathers must vent into a collection bottle.
I will run my hand along the bottom of the fairing catch tray, this must be solid with no holes in it and constructed to hold at least half of the total oil and coolant capacity of the engine (generally all race fairings are designed to this spec) as well as the fact that any openings in the fairing are at least 50mm above the bottom of the fairing. If drain plugs have been fitted these must be taped in place from both sides.
Check left hand side foot peg has rounded ends, if standard ‘flip up type’ pegs are used hero blobs have to be removed. Make sure no excessive play or loose joints on gear shift mechanism. Side stand removed? (Yes it does happen!)
I will check the rear shock visually as well as the upper and lower mounting bolts, I will ensure there is no play in the wheel bearings or swing arm by forcing the wheel from side to side. Shark fin fitted?
Check right hand side foot peg has rounded ends, if standard ‘flip up type’ pegs are used hero blobs have to be removed, rear brake lever securely fitted and not fouling on any part of machine.
From here I will move to the top of the bike and check fuel tank/filler cap is securely fastened, give the rear seat unit a tug and make sure mounting is solid.
Assuming the bike passes inspection your card will be signed and a ‘Day Sticker’ affixed to your bike.
NOTE: Technical officials are here to get you on track, not to try and stop you. We will endeavour to be as polite and helpful as we can be to get you on track and to enjoy your racing.