Weights and measures.

Don’t get me started on the fuel range of modern bikes. Oh, go on then…

Has anybody else noticed the disturbing trend of fitting modern bikes with pathetically small fuel tanks? A lot of modern sports bikes won’t manage more than 100 miles before the warning light comes on, some even less than that. On a road bike this can be inconvenient, on a dirt bike it can be potentially quite serious especially if like me, you ride in some of the more remote parts of the UK.

Fuel range on trail bikes is usually the most critical aspect to consider when planning a ride. It certainly dominates my thoughts when planning a customer day out. I can plot any number of 100 mile loops around these parts and I guarantee there will only be one fuel stop option available on any of the rides. The closure of rural petrol stations doesn’t help but it’s the bike manufacturers who are the real culprits.

Fill ‘er up please mate and don’t forget the Green Shield stamps

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Consider this; I reckon the average fuel consumption of a smallish dirt bike is around 10 miles per litre when ridden off road. In English money that’s around 50mpg.  KTM’s Freeride is the Austrian manufacturer’s take on the current  trail/trial hybrid genre which is slowly taking root in the market. It’s got a 5.5 litre tank.

Let me tell you, you won’t be riding free on that for very long. Even worse is Scorpa’s ironically named Long Ride with its 4.5 litre fuel capacity . I dunno about you but 45 miles isn’t a particularly long ride in my opinion. And that’s assuming the quoted tank capacity is correct…

On a couple of occasions I’ve had to top up the Gas Gas Pamperas from the stash of fuel I carry in my rucksack for such emergencies. The Pamps had run out of fuel almost an hour earlier than I had calculated. The Pampera handbook states very clearly the fuel capacity is a class-leading 9 litres. Allegedly. The sensible tank capacity is one of the reasons I chose the Pamperas for the trail riding business. Consequently I was  puzzled when they ran out of fuel prematurely on these two occasions and put it down to the customers being a little throttle happy. A few days after  the second incident it was still gnawing at my subconscious and I decided to measure the tank capacity properly.Just for the record let me state the fuel capacity of a MK3 Gas Gas Pampera is not the useful 9 litres quoted in the handbook. It’s a barely acceptable 6.8 litres. Shame on you Gas Gas for telling such porkies. On Offa’s Dyke running out of fuel was mildly inconvenient but easily resolved due to my OCD habit of carting around spare fuel . Imagine if this had happened in the wilderness? With four customers in tow ?

I’ve solved the problem on the Pamperas by purchasing some natty Acerbis auxiliary fuel tanks.  These carry two litres and handily replace most of the mysterious missing capacity from the Gas Gas gas tank [ sorry, couldn’t resist it ]. The Acerbis tank is plumbed into the Gas Gas gas cap [again, sorry…] and works by syphonic action – you have to make sure the bike’s tank is full to make this work. The handy thing about this is the handlebar tank drains first thus relieving the weight off the handlebars early on in the ride. Neat.

Once it’s empty the Acerbis handlebar tank doubles up as a useful buoyancy aid

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So what is it with these small tanks? My 1975 Laverda Chott had a genuine 9 litre capacity which gave 110 mile range. It was also light and quick. How come Laverda [and other manufacturers] managed to get it right 35 years ago and nowadays some aspects of bike design seem to going backwards?

It’s a combination of things . Packaging for one. Bikes have more and more mass centralisation and manufacturers pack a lot of stuff towards the centre of the bike such as carbs, exhausts, ECUs, radiators etc etc leaving less room for fuel. The manufacturers also have to quote competitive wet weights to stay ahead of the competition and a small tank helps this. Air cooling would resolve a lot of this and allow more room and fuel capacity. Unfortunately manufacturers would struggle to get the high specific power outputs customers now demand [even though very few of us can actually use it].  Indirectly, water cooling also helps to reduce emissions and controls decibels. In the end bike design is all about compromise and deciding which set of compromises will be acceptable to the market. Latterly , it seems , manufacturers have decided modern riders don’t ride their bikes very far and therefore the designers can cut down the amount of space devoted to carrying fuel.

Now then, don’t get me started on seat height and dry weight. Oh go on then, maybe next time…

This is the reckless consequence of an inadequate  four litre tank capacity. Taken some years ago this pic shows me filling up five x 1 litre Sigg fuel bottles to augment the small trials tank on my Yamaha Majesty during the  Edinburgh Trial. At one point during the twenty hour event I was falling behind on standard time and through a dangerous combination of fatigue, desperation and stupidity I actually removed a bottle from my rucksack and attempted some in-flight re-fueling whilst traveling at 40 mph. Good sense prevailed prior to spontaneous combustion and I pulled in to continue refueling in a more responsible manner. Happy days.

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