UKH

Always used to enjoy riding, much more so than driving a car. I used to have a Honda CB400n which was plenty fast enough for me.although I only every used it as a means of getting aroung, didn't really just go out for a ride. 

I like the idea of getting a bike again and definatley would if it was more economical than my car, but it seems you can't get many bikes that are noticably more frugal than my skoda fabia (1.6 deisel, maybe 60mpg).

I don't understand why you can't get a reasonable bike that could be nice  to ride, could cruise at 70 on a motorway and do 100+mpg. Does such a thing exist?Seems like there would be a big market for it. I'd buy one anyway.

Guessing anything smaller than 400cc would struggle a bit on motorways, especialy if carrying a bit of luggage?

It seems that most bikes are aimed more at the performance end of the market, even so called commuter bikes. 

If anyone can enlighten me about a bike that meets my needs, or why such a thing doesn't exist I'm all ears.

I'm thinking the same but keep getting drawn to bikes that I really shouldn't buy!

A mate has just picked up a 2 year old CBX 500 with 10k on it. I had a ride on it last week and it was bloody great....I never thought it would be as good as he said it was being a 500 but I loved it! He's getting very good mpg from it....I'll message him and see what he is getting rather than what the marketing stuff says...

It'd make a good all round bike....commuting, light touring etc...

His reply....averaging 71 mpg commuting Buxton to Macclesfield....about 30 miles per day with some town/rush hour stuff getting across Macc in the morning but mostly open road doing 50 mph....

Thanks for the reply but only getting 10mpg more out of a bike compared to my car probably isn't going to tempt me. 

If I can get 60mpg out of my 1.6l car, 70mpg out of a 0.5l bike that would be less than half the weight and less than half the wind resistance doesn't sound that great an improvement, although I do know I would enjoy the bike more.

Yep agree....I think car engines are just so much more economical than they used to be so they compare well to bikes when in the past they didn't! There are probably some bikes around doing good mpg but whether you'd actually want one is another matter....

I can always buy cars with rational thinking but it goes out of the window with bikes...

Have you looked into electric motorbikes? Interesting if they work... 

You need a Yamaha R125 - 110mpg, 70+ mph all on 15 hp. About 5k new. My 125, a Honda Innova, can do 60 mph or cruise at 50. I used to commute 70 miles return journey and got 160mpg over 11,000 miles. Had 2 Suzuki V-stroms, 650cc twin, latest has injection, old one carbs but could get 75mpg at 60mph. Even my 1200 BMW got 60mpg on a good day. But who rides for economy - it's difficult to get mpg figures from manufacturers, most bikers don't seem that bothered...

Royal Enfield have a new economy bike, reviews well but made in India and won't cruise at 70. Honda's NC750 is very economical, I enjoyed my test ride but preferred the Suzuki handling.

Added bonus you get to look like a circus clown on a tiny bike. 

Bikes just aren't economical, cars are designed to slip through the air, no matter what you do a bike won't be aerodynamic. 

I used to get 50 mpg out of my 1200GS BMW and my 1200 Triumph Explorer, currently getting 60 mpg got of my 650 Kawasaki Versys. 

I loved my old superdream, but.. as fond as my memories are, I'm sure I wasn't getting 100mpg from it maybe I was always wringing its neck, although in those days it didn't matter so much

It won’t cruise at 70 on the motorway but, on its first run, my 2022 CB125F has done more than 300 km on less than half a tank. Economical? Overall, better than an electric bike?

Honda nc750x.  Low revving  easy to ride and up to 80 mpg. Great all round  bike

I ride a Tracer 900 and get between 60 and 70 mpg. It’s a good fun bike and also copes well with long distances. My car gets 30 to 40 mpg (Fabia VRS) so the bike is much more economical for me. 

Can't stop drooling over these bikes. After hours of googling 0-60s and top speeds I've decided I need the 650 twin. 

I bought a CB300R 4 years ago for getting around after having 2 CBR1000’s that I used to use for commuting. Admittedly it doesn’t have the warp drive function of the CBR’s but it’s a nice ride, nippy enough, and far less likely to get me banned. It mostly returns 100MPG+ but two problems are that there is no way to secure a load on the back seat unless you fit a rack/back box and no centre stand.

Thanks Mark, that looks like the closest yet to what I'm interested in. But it is naked, what's it like at 70 on a motorway?

The CBR300R is the faired version.

All smaller/lighter bikes suffer on motorways from wind buffeting mainly from lorries but that's the nature of the things.

I’ve not done any motorway riding on it, but getting up to 70 on a dual carriageway isn’t difficult or uncomfortable, for the short trips I do. Although if I was spending significant time on motorways I would choose something bigger, just to have the spare power in case I needed it.

I guess the energy involved in manufacturing bikes is much less, but that wouldn't justify buying one if you have a car already. 

The less sport-bike version of the CBR is the CRF300 Rally by the way, Honda use the same engine platform for loads of models.

300's are the new 400 class, engine tech has come a long way and balancer shafts made the expense and weight of twins kinda redundant. Another would be the BMW G 310R or GS.

I wasn't suggesting i got 100mpg+ out of my CB400n (superdream), just thats what I was hoping to get out of a bike to make it worth it financially to run a (small) bike and a small car.

If you can only get 70 - 80 out of a bike, financially I might as well just run my small car.

When I had the superdream, it was my only transport

Another vote for the NC750. Doesn't seem to matter how I ride it, but 70 to 80mpg is normal 

It's worth noting that comparing the stated mpg for cars to motorcycles is fairly worthless, it's done differently and uses different parameters to derive the value (it's calculated not measured).

For the largest database of real-user values one goes to www.spritmonitor.de which gives a better indication of what people actually get. It's in English if you wish.

This thread chimes for me with recently noticing the reek of unburnt hydrocarbon which follows any motorbike (presumably club) procession that you might pass on any country road on a good weekend. Why are bikes allowed to be smelly and inefficient?

I’ve also had the same musings about a bike for short journeys but too many objective dangers for me.

That isn't a feature of motorbikes specifically, and definitely not modern ones.  You get unburnt fuel coming out of the exhausts of petrol engines with carburettors, and it just so happens that there are more 'vintage' bikes with conventionally aspirated engines about than there are cars.

Keeping a vintage bike on the road is cheaper and more accessible than a car, so naturally there are more hobbyists doing it though even so hardly anyone uses one for daily commuting.

I stumbled across a scooter rally the other week, holy cow I'd almost forgotten how stinky those little 2-stroke engines running on pre-mix were.  I could smell those bad boys from (perhaps literally) a mile away!

Thats a useful site, thanks Jim.

I think you mean fuelled rather than aspirated, which latter term refers to how the air is delivered to the cylinder - basically, how the engine "breathes".  The alternatives to normal aspiration being turbocharging and/or supercharging.  There's no technical dependency between fuelling and aspiration: either fuelling method can be used with either normal or forced aspiration (my mid-1980s Renault 5 Turbo had a high-pressure carburettor, for example).

That said, there are probably a few turbocharged production bikes from the early 80s still running around (each one of the Japanese "big four" produced a turbo bike in that period) but I don't think I'd want to go anywhere near one!  Apparently three of them were "blacklisted" by US insurers.  I understand that Kawasaki have produced three turbocharged variants of the 1000cc Ninja in recent years.  I suppose the technology has moved on a bit since the 1980s but still...

I’m old enough to have run, and tinkered with, numerous carburated cars as well as a couple of 50’s motorcycles. I can recall always having to buy new gaskets, gland seals and other bits for the fuel system but I never tolerated the amount of smoke and stink you still see.

so it’s just bad maintenance then?

More likely people carrying out "performance" mods without having a clue what they are doing. Louder is faster. 

I did, ta.  Wasn't thinking.  Not fuel-injected is what I meant.

An old friend of mine had a turbocharged Z1000, it was terrifying.

I think that's pretty retro too these days.  It's been a long, long time now since it was a rite of passage trying to wring an extra half a horsepower out of your Fizzie.

Motorbikes have terrible drag coefficients. All those exposed gubbins. A quick google suggests bikes vary from 0.5 to 1.0. A Tesla has a drag coefficient of 0.2 with 0.3 being typical for a modern car. The new range rover is 0.32 for example.

Weight doesn't affect fuel efficiency at high speeds all that much. It has an impact on urban stop start driving, but once you are up to speed, all that really matters is wind resistance and motor efficiency.

So a bike is always going to struggle to get the efficiencies of a modern car purely down to drag. 

To tune an engine for low down power, keeping things efficient,you need really long intake manifold. Again, packaging on a motorbike makes this a challenge, so they lend themselves to higher end power which reduces their mpg. Makes then fun tho'

I have a Honda NC750 - D Integra . Not very exciting but super comfy, will cruise at faster than legal with ease if you so desire and DCT gearbox so no faffing changing gears. 

I have motorbike commuted for 25 years and have had all sorts of bikes from 125cc scooters to 1000cc sport bikes. This Honda is the best one for commuting for my journey (25 miles of country lanes/motorway/dual carriageway). Its very economical for a motorbike, yes you can get cars that are equivalent, maybe better BUT!!!! They spend most of the journey stationary or crawling along bumper to bumper. That's where the real fuel savings are made!

i have a Honda cb125f and i wouldnt go on a motorway as i could get up to speed but id have no acceleration 

Aerodynamic drag is a multiple of both the drag coefficient and the reference area (plus speed squared, density etc). Reference area is probably the frontal cross section for a vehicle. So nominally if you have a bike with 25% the frontal area of a car, but four times the drag coefficient, it would have approximately the same aerodynamic drag as the car. If you have a bike with a 1/6 the frontal area of a car but double the drag coefficient, it will suffer three times less drag force. Etc. Best to crouch down low.

So as an aside, characterising something like a Range Rover as being relatively ok drag-wise because it has a Cd of 0.32 is missing the point, because it's really big so it is going to suffer a lot of drag.

As an another aside, if you know Teslas you might have seen articles stating that the Model 3 and Y both have the same drag coefficient. They entirely miss the point that the larger frontal area of the Y is not accounted for in the drag coefficient, it's a separate factor in the drag equation.

To the OP,  I know nothing about ebikes but I follow a few EV related YouTube channels and it seems that ebikes, like EV cars, have come on massively recently. We are talking proper electric bikes equivalent to a motorbike, not electrified bicycles, if that makes sense. One of such YouTubers has just done Lands End to John O'Groats on one. Running costs dirt cheap, no doubt needed lots of charging stops. Could be well worth a look, I don't know how quick they can be.

Fully aware of this, but I can never seem to get my hands on front cross-sectional areas. Cd values seem to be easily available.

As far a bikes cross-sectional area. Don't underestimate it. Height wise a bike is much taller than most cars on the road. Unless you're bent over the tank, you're normally towering over the cars.

Vehicle aerodynamics is hideously complex, unless you are going along an empty road in still air any of the simplistic value are worthless. Heavy trucks who really struggle with this have a side-wind factor because a wind from 45° really kills them, watch an artic overtake another one and when they get just past equal height the overtaker effectively stops as their wind is now coming from the sideat an angle. On a motorcycle one has the same effect from the traffic around you and probably worse as the Cd value at an oblique angle has got to be disastrous.

E bikes are coming, BMW just launched one for commuters (well it's a big scooter really). Costs twice as much as a GS310 and it's gigantic though, twelve grand to sit in the rain isn't my thing!

Thank you Si, for the detail on coefficient of drag and frontal area. From Montys post I was starting to wonder if it could be possible that a bike had more drag than a car.

I'm sure it must be complicated with a bike profile being taller than many cars, and with the less smooth outline of a bike. But I imagine total drag must be less on most bikes, than on most cars.

Obviously that's totally unscientific guesswork/assumption.

Where are you getting half the wind resistance from? Frontal area is smaller but Cd of a bike and rider is horrible compared to a modern car. Add to the significant drag a high revving naturally aspirated petrol and it's no surprise it doesn't do any better than a turbo diesel that has had a lot of aerodynamic sticking plasters put on it.

Jk

to put some figures to it:

https://www.engineeringtoolbox.com/drag-coefficient-d_627.html

model 3: 0.23

vauxhall vectra: 0.29

motorbike and rider: 1.8

I don't have the figures for frontal area, but what this effectively means is that a typical car could have a frontal area six times bigger than a motorbike and rider and still have the same total drag

You're right in that there are lots of factors that make real world aerodynamics a tad complex, but it always used to annoy me that car manufacturers quoted Cd rather than CdA, which is a much better comparator.

I know why they did (and still do) it, basically they're just doing a bit of willy waving, which will impress those who are easily impressed.

It's really the best measure of the aerodynamic design quality, the frontal area is largely driven by the size of us and our commercial refusal to move far from the norm of what 'a car' looks like. VW's XL1 broke that mould but then it didn't catch on, what actually happened was lots of little tricks used to make a shape flow well are applied to things that still look like what we'd call a car (think Model 3). It's pretty cool if you look closely at a modern car, even big stupid 4x4's have ducted air screening their front wheels to control wheel well turbulence, flat under floors and almost every modern car has little trip creases and lips moulded into rear panels, light covers, window seals etc at the to turn the fashion/function driven rear into a quite effective Kamm-back type shape at least from the air's perspective.

The Calibra is the car that always surprises me, it's from long before the era of neat CFD driven trickery and fuel economy concerns, it's just a really nice and presumably well detailed shape, without looking odd it is remarkably slippery (or oversold!).

jk

The opportunities to improve the aero on a modern car are a source of envy for motorcycle designers! Electric ones even more so as a hugely overlooked problem is cooling, in a conventional i.c car one can at least clean up the dirty air from the radiator, dump it somewhere fairly harmless and then use it to help the rear turbulence. On a motorcycle all you can do is hope to get the same amount of hot air away from the rider and passenger without causing horrendous extra turbulence problems. Honda screwed it at the weekend at the German GP where they cooked the riders and they gave up.

But for example, Range Rover saying their Cd is 0.29 (made up figure) is missing the point because the Rangie is basically a bus and will have more air resistance than any normal sized car.

I suppose it does show how much effort they've put into making it as aerodynamic as possible, and it does show improvement since the previous version but as a comparison with other vehicles it's not much use.

If I'd been able to get away with 3 doors then I'd have had a Calibra. Needing 5 doors I had to settle for a Cavalier SRi.

I wonder how much further modern trickery would have got the CD down.

Not with the bikers I know, look at my new can, it's bumped the HP from 200 to 205, we'll worth £800, listen to how loud it is. My penis is 18 inch long. 

But how aerodynamic is it? The penis, that is..

Turbo's are so 1980's the Kawi models you're thinking are now Supercharged.

Ninja H2 , H2 SX and the Z H2 are the three variants all based on Kawasaki's 1000cc supercharged engine.

You are, of course, absolutely correct.  I skim-read the Wiki article about forced induction too quickly and din't spot the switch from turbo to super!

I remember reading about some of the 1980s turbocharged bikes when they first came out and thinking that, even if the reviewer said that the turbo lag wasn't too bad, it was still something that wouldn't really be much fun to have to deal with on a motorcycle.

(I have heard that a key part of Ayrton Senna's driving style was to blip the throttle through corners, so as to reduce the lag when he started to open the throttle on the corner exit: https://www.youtube.com/watch?v=dEFMPnJJ9EE&t=155s  I wouldn't want to be trying to play those kind of tricks on two wheels...)

My Enfield 500 will easily give me 90 to the gallon. 95 is possible. Thats with 19" trials tyres at bugger all psi as well. I had a CRF230 that would touch the 100 and gave me 95 over 600 miles with monster panniers around the Scottish west coast.

Royal Enfield did make a diesel powered bullet that had a quoted mpg of nearly 200 - might find one second hand somewhere 

All depends on the riding in the real world, my vstrom won’t have great figures quoted but given around here half the time anyone is in a car they are stationary - usually with the engine still on - and I have gone straight past them, I noticed a massive saving compared to commuting by car when I used to do that. 
 

bikes depreciate so much slower than cars as well so you wouldn’t risk that much giving it a try if there was a bike you really liked the look of.

There is also the fact that directly comparing the mpg of a diesel to a petrol vehicle and relating this to efficiency is flawed, diesel carries ca. 18% more energy by volume.

I spoke to someone who saw (and maybe rode ?) one - vibration was terrible he said. Would be interested to have another opinion though.

That's the main difference I found too. 20 to 25 minutes by motorbike compared to 45 minutes or more by car. That means 20 minutes (or nearly 50% of journey time) minimum just sitting there.

And you can't say modern (ICE) cars that "cut out" when stationary are much better, as in a queue of traffic you're constantly having to edge forward one or two car lengths as vehicles in front get clear, so restarting is continual - can't help the starter motors in that situation either.