[carsQhere]

The following is the definitive last word on restricted licence power to weight ratios:

Part 1 - a tiny bit of history...
The original restricted license proposal came from the EU, specifically Council Directive 91/439/EEC of 29 July 1991 on driving licences.
http://eur-lex.europa.eu/LexUriServ/LexUri...91L0439:EN:HTML

Quote

Article 6, 1 b stated;

-for category A; however, access to the driving of motorcycles with a power exceeding 25 kW or a power/weight ratio exceeding 0,16 kW/kg (or motorcycles with sidecars with a power/weight ratio exceeding 0,16 kW/kg) shall be subject to a minimum of two years' experience on motorcycles with lower specifications under an A licence; this requirement as to previous experience may be waived if the candidate is at least 21 years old, subject to the candidate's passing a specific test of skills and behaviour;

The Irish Government gave it the following interpretation in the ROAD TRAFFIC (LICENSING OF DRIVERS) REGULATIONS, 1999. (S.I. No. 352 of 1999)
Section 17, Part 2 (taken from: http://www.irishstatutebook.ie/1999/en/si/...l#partii-sec17) which reads as follows:

Quote

Motorcycle engine size restriction.
17. A person granted a provisional licence for the first time on or after the commencement of these Regulations to drive vehicles in category A and who on obtaining a certificate of competency in that category is subsequently granted a driving licence in that category, shall, until a period of two years after the grant of the latter licence, be restricted to driving only those vehicles in the said category which have a power output not exceeding 25 kW or a power/weight ratio not exceeding 0.16 kW/kg, or in the case of vehicles in the said category with sidecars, with a power/weight ratio not exceeding 0.16 kW/kg.

So the magic word above is or - you could ride a 100bhp bike on a restricted license if it was heavy enough to come in under 0.16kW/kg.


Part 2 - where does this leave me if I am on a restricted license?
Or, how do we work out if our bike is leagl to ride on a restricted license?

First, We need to know the weight of our bike. To determine this we can use either the manufacturers quoted figures, or go to our nearest DOE test centre and ask them nicely to put the bike on their weighbridge.

Second, we need to know the power output of our bike. The only accurate way to measure this is on a dyno, so in most cases we use the manufacturers quoted figure for our particular model. Manufacturer figures are usually optimistic, and your new bike will normally produce less than the stated power. By the time you buy it second hand, your bike could be down as much as 20% on the manufacturers stated figure, so again a dyno is the only way to accurately determine the bike's power output.

Third, we need to do some maths. Lucky for most of us, the maths bit is not too difficult!

So let's get stuck in...
Bike manufacturers quote power output in bhp (brake horse power). The law talks kW (Kilowatts). So we need to convert bhp to kW;

Power Conversion:
1 kilowatt = 1.341022 brake horse power
25 kilowatts = 33.52555 bhp
(Note: The commonly accepted conversion is 1.34 bhp = 1 kW)

Example 1: A Honda Deauville with a claimed weight of 228 kilograms, putting out 55bhp on the dyno.
First we convert bhp to kilowatts: 55bhp divided by 1.341022 = 41.01 kW
Next we divide the output by the weight: 41.01 divided by 228 = 0.179 kW/kg
The law says 0.16 kW/kg, so this bike at 0.179 kW/kg is over the limit, so not learner/restriction legal.


Example 2: Harley Davidson 883 Sportster with a claimed weight of 260kg & measured power output of 45bhp on the dyno.
We convert bhp to kilowatts: 45bhp divided by 1.341022 = 33.55kW
Now we divide the output by the weight: 33.55 divided by 260kg = 0.129 kW/kg which is well under the 0.16 kW/kg limit.

So our example HD Sportster is well inside the legal power to weight ratio, and can be ridden on a restricted license.

Remember, the key word in the legislation is "or". Either 33bhp OR under 0.16kW/kg.
The law does not:
- limit the capacity of the engine
- specify how the weight of the bike is measured (e.g. with rider or without)
- refer to the torque (pulling power) of the engine.

So long as you can prove that you are within the power to weight ratio of 0.16 kW/kg you are legal on a restricted licence.

UPDATE JUNE 2010

This thread on boards.ie suggests that at least one rider has been prosecuted for riding a full power bike on a restricted license. It would appear that the court used or accepted the manufacturers quoted weight and power for the bike.

The case was allegedly taken in Cork. If anyone can shed further light on that, it'd be great because it would be useful to have a precedent we could refer to.

Horrible disclaimer bit hiding at the bottom...
The above information is given in good faith, errors or omissions excepted. It is intended as a guide only. I am not a lawyer, and this is not a legal document. You alone are responsible for ensuring that you comply with the law. If in doubt, seek qualified advice. Your insurance may be invalid if you breach the terms of your license. Where the insurance company pays out on a claim, it may seek to recover the costs from you if you are found to be in breach of your license.

This post has been edited by KildareMan: 28 June 2010 - 06:47 PM

[klu]

You're not a mechanic (no idea if you actually are) but if you've a letter from Honda stating your bike is learner legal what more could ya need?

[proinnsias]

seancullen, on 01 November 2010 - 07:32 PM, said:

the cb im on in the cb500s, have a letter from honda stating that the standard cb is learner legal, so the slightly heavier cb500s must be, according to them its 0.15kw/kg

http://www.bikez.com..._sport_1998.php

from here it is listed as 179KG dry and 42.3kw 0.324HP/kg, which is 0.24kw/kg, in other words over the limit.

then according to http://www.mbike.com...500s/1999/print
it is 198kg wet and puts out 41.6kw or in hp terms 56.56HP which is equal to 0.21 HP/kg or 0.15kw/kg. (according to that particular website)

So that'd be 41.6kW / 198kg = 0.21 kW/kg (over the limit)

seancullen, on 01 November 2010 - 07:32 PM, said:

now the question to ask is this, where did that website and honda pull the 0.15kw/kg figure out of?

Just a thought - someone (more than one someone) stuffed up their numbers :

0.21 kW/kg : if we take the conversion factor for HP -> kW (1.39:1) and divide the 0.21kW/kg number by that : we get 0.15

Looks like someone messed up their units, and double-converted :

So: CB500 Power to Weight:

58HP / 198kg = 0.293 HP / kg (0.21 kW/kg)

Double that conversion and you get 0.15 somethings/kg ... but those somethings are not kW


P

[seancullen]

well that sucks

[ChickenStrip]

proinnsias, on 01 November 2010 - 12:46 AM, said:

Definitive :



New Legislation - once we implement the 3rd EU Driver Licencing Directive (sometime in January) will become :
A2 Licence (same as current restricted A, just has a name now) :

35kW (approx 47bhp) and 0.2kW/kg and must not have been derived from a bike of more than double that restricted power.

An interesting twist, and one which is going to cause some confusion when it does come in - as I know of at least one mechanic who has even recently been asked to restrict certain 1300cc Suzuki sportsbikes.

Wow, Im confused. So will this 35kw(47bhp) restriction apply to only these new A2s or restricted A licenses as well?

And if this higher limit does apply, does that then mean that the "no more than double" limit applies to A's as well?

This post has been edited by ChickenStrip: 04 November 2010 - 09:45 AM

[proinnsias]

ChickenStrip, on 04 November 2010 - 09:36 AM, said:

Wow, Im confused. So will this 35kw(47bhp) restriction apply to only these new A2s or restricted A licenses as well?

And if this higher limit does apply, does that then mean that the "no more than double" limit applies to A's as well?

New A2s only

It would seem not - unless (as proposed) the RSA implement a full "licence exchange programme" requiring everyone to upgrade to a new credit-card licence ... it's possible they would migrate you to the new categories at that point. (unknown, and unlikely to be of major consequence for most)

P