Weight & 125cc's

[Manchop]

Hey again people;

I'm gonna get this out in the open for a friend that is wanting to do his CBT with me, but is worried about his weight and if a 125 (Cruiser/Chopper) will be able to pull his weight, and if the bike will produce at least 50+ mph

He is 20st, and believes he cannot go on the roads as a 125cc bike will not be able to reach 30 mph while he is on it, though we plan to buy cruiser/chopper type bikes.

What do you guys think? Should he continue is basically what he asks.


Thanks in advance for any responses, hopefully nice ones as he reads replies with me :-p haha

[trevor saxe-coburg-gotha]

It's more about drag than weight - i.e. size. I'm not exactly svelte, and my kids're a good five stone each. With me and one of them on we're well over fifteen stone, well over. And the both the 125s of mine will do 50, on the straight and level. Dips below on hills and against the wind, for sure. But anyway - it's not about weight so much as drag.
____________________
"Life is a sexually transmitted disease and the mortality rate is one hundred percent."

Mobylette Type 50 ---> Raleigh Grifter ---> Neval Minsk 125

[wr6133]

I'm 16 stone and the only 125 I have not been able to get to 60 or more is one of those semi auto/clutchless Honda step through things. My old Jinlun would manage 60 with the wife on the back and that was a combined weight of just under 23 stone, just took longer to get there. So he should be fine though his body would probably thank him if he lost some weight.

[andyscooter]

wouldnt reccomend chinese criusers though as they tend to get stuck at 50mph and are underpowered
____________________
gilera runner vxr200 (chavped)
if its spelt wrong its my fat fingers and daft auto correct on my tablet

[wr6133]

[The Shaggy D.A.]

[bamt]

Definitely go for the CBT. It's an experience if nothing else, and it should set his mind to rest about a 125.

But being on the well-built side and wanting to ride a cruiser, well that just means that he should be aiming for DAS at some point then he'll fit in nicely with the Harley crowd without even needing to go on a body building course

[Teflon-Mike]

https://i178.photobucket.com/albums/w269/teflons-torque/Little%20Dreams/100_0067.jpg
This Chinese Cruiserette, would lumber up to 55mph... max.

Didn't really matter if it was ridden solo or if Snowie & I were 2-Up on it. A combined passenger weight well in excess of 20 stone. And the bike itself wasn't exactly anorexic; think the damn thing was about as heavy as her Moto-Guzzi 750!

But I have to say I do not really recommend a Chinese Cruiserette ... I don't really recommend any 125 Cruiserette ... and I struggle to find much to recommend any Chinese bike... for any-one... let alone as a learner-bike, but that's another matter.

Point is your mates 'worry' is unfounded; any 125, even a crappy Chinky Cruiserette should be able to lug his lard to more than 50.. As Trevor said, speed is a function of aerodynamics not weight, really.

The pertinent equation is Power = Drag x Speed, so how fast you go is set by how much power you have, and how much wind resistance there is. Mass only really comes into the equation, Force = Mass x Acceleration, so heavier the 'vehicle', slower it will accelerate, to whatever top speed its power will allow, but it should still get there.

Where bikes are 'slower' with a larger rider on them, it IS mainly because the rider is physically larger, not because they are heavier.

Drag is pretty much proportional to the 'frontal area' presented to wind resistance; and your heavier rider will tend to be taller and wider than a lighter one; so present more of a 'barn door' to the wind, like an air-brake.

But, wind resistance increases exponentially with speed; for an average sized rider, you only need about 3bhp to go 30mph; to go 60mph, you need about 9bhp, so three times the power to get twice the speed; but then it starts ramping much more steeply; 20bhp will get you to around 80, but you need about 30bhp to nudge 100. 60bhp will just about get you to 120.

But, point is that on a power limited 'learner-legal', you dont have the power to go much over 60 anyway, and under 60mph you are on a very shallow portion of the speed/power curve, where it wont really make massive difference... well, in real world mph.

Should your mate carry on? Well, who are we to tell him what to do?

Does he WANT to ride a motorbike, or is he making excuses not to?

Does he want to ride a lightweight or is he making excuses, because they dont fit his aspirations of the kind of bike he would like?

And why is this YOUR problem?

Are you trying to encourage him so you have a riding buddy? Or because HE actually wants to be on a bike?

That line of enquiry needs bottoming out here first; Does he REALLY want to ride a motorbike, what bike, and WHY?

You have to be an enthusiast to ride a bike; its too compromised, uncomfortable, and generally scary other wise, and if some-one HAS the enthusiasm to ride a bike.... they tend not to need much encouragement from other people, they'll do it for themselves... so if he's NOT done it for himself? Well, probably doesn't have the enthusiasm for it, and you are on a road to no-where trying to encourage him.
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[Rogerborg]

Ah, good old Teffers, putting people off biking since 1867.

Tell your mate to get a Honda Superdream. All the pushing will see those pounds just melt away.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Kickstart]

Hi

Weight has remarkably little effect on top speed (ie, to do 60mph needs very roughly 40 lbs of thrust, and it takes as a rule of thumb 1% of the weight in pounds of the bike / rider to overcome, so 20 stone in total only requires 2.8lbs of thrust to move). But heavy tends to mean big, and that affects aerodynamics.

But plenty of cheap 4 stroke 125s struggle to do a decent speed whoever is riding them.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[hedgehugger]

I had a Yamaha SR125. Not the fastest bike to start with. When I pillioned my daughter there was a combined weight of around 20 stone. It would get up to it's usual speeds eventually, and had no probs up hills, hitting 55 quickly, could maintain that easily.

[Manchop]

Thanks for the replies guys, it's given him a bit of optimism and he is now committed! (Else he owes me £300 ;D)

- We also mentioned Trikes? (2 wheels at the back) .. what is required to ride a trike that's 125cc? I've looked at the DVLA licence tables and to be honest it's still not crystal clear, and I have also read mixed information on the internet.

Is a 125cc Trike possible on a CBT Provisional License? Curiosity killed the cat :-p

[talkToTheHat]

Look as the max payload for these bikes, some chinese bikes will struggle, japanese workhorses should be ok. I'm 15 stone and used to tour on a GZ125, not to mention doing my shopping and the like, so I'm sure I had the other side of 20 stone on it a few times. It's well within the stamped payload for such a bike.

Worry not, ride more.

[Rogerborg]

[trevor saxe-coburg-gotha]

What can I say. Sometimes truth does not obey the boundaries of creed, culture or consanguinity.
____________________
"Life is a sexually transmitted disease and the mortality rate is one hundred percent."

Mobylette Type 50 ---> Raleigh Grifter ---> Neval Minsk 125

[sidewinder]

Does it have to be cruiser type.maybe a varadero may suit him better.

[Teflon-Mike]

[MCW]

Tell him to get a varadero 125. Not only will it cope with his weight, he won't look like a bear on a tricycle on it. And they're luvverly. I cried when the chap who bought mine rode off on it.

[Yaka]

[merquis00]

^ my neighbour had a varadero and he was a fellow fatty, he looked normal/non circus-like on it and used it for work everyday without trouble.

WRX (or another of the same style) is also a good option, I'm 17 stone and "short" but my weight pushes the bike down a bit and i can touch the floor, it also reaches and stays at 60+ without much effort.
____________________
Current: 2010 WR125X, Carrera crossfire-E.
Project's: '88 GL1500 Trike, Chinese 170cc Monkey
Previous: X9-500, XT125, DNA125, CBF125, YZF-R125, '98 K1200RS, '99 St1100, fantic245

[talkToTheHat]

the varadero is an ace bike, at the top end of the 15 horse limit, really big so even a giant of a man can't make it look like a mini-moto. Favoured weapon of some of the local 125 warriors. I considered getting one once, but was put off by the high seat as I have really short legs.

[Manchop]

Thanks for the replies and the giggles (Japanese vs China thing haha) Yeah that Varadero he dislikes, does't like the style of it at all unfortunately.

What do you guys believe is the top end of the speed section in regards to cruisers/choppers? I know they're not built for speed etc, just curious.

I also noticed something, which is again confusing me to high-hell.

My provisional driving license states;

[Rogerborg]

"Provisional". There are a list of conditions to which you need to adhere in order to use that provisional entitlement.

Have completed (or presumably be on, although I've actually never seen that explicitly spelled out) a CBT course.
Be displaying L plates front and rear.
Be an AM category moped.
Be at least 17 and on an A1 category (<=125cc <=11kW <= 0.1 kW/kg) bike.
Be at least 19 and on a bike making up to 35kW and not derived from a bike making twice its power and not making more than 0.2 kW/kg, and wearing fluorescent (or at night, retro-reflective) clothing and be in radio contact with a certified DAS instructor in possession of his certificate with no more than one other A2 or A provisional Learner in contact.
Be at least 24, or 2 years after passing A2, on any bike, wearing fluorescent (or at night, retro-reflective) clothing and be in radio contact with a certified DAS instructor in possession of his certificate with no more than 1 other A2 or A provisional Learner in contact.

Can you see why they don't print all that on the license?
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Teflon-Mike]

[wr6133]

Mike what lexmoto sold as a Texan was a Jinlun 125-11. Its the twin engine not single only difference over the actual Jinlun badged one is they used clear indicators. It's a copy of a marauder frame (the jl125-13 is the rebel clone). They also sold the Nevada but called it the torro that has the single (name change was because another importer had rights to "Nevada"). They also sold some pile of crap called the "lowride" which by all accounts is something to avoid like the plague I've yet to hear about lowride owner who doesn't have buyers remorse.

I've ridden a few Nev/torro's and Jinluns they edge a bit over 60 though the Jinluns seem to do it easier.

Nothing wrong with 125 cruiserettes, if you are stuck on a 125 and want something relatively chilled out. I loved my 125-11 only went up to a 250 because the steep hill 1/4 mile from my house and motorways became a pain in the arse.