My feelings are these…they may well be wrong however.
Leathers with humps are worn by moto gp riders and other bike racers too. Do they perform any real function or do they plain look cool and that’s it. In some very hot races racers use them to store fluids to consume during the race. This is the ONLY use i see for them.
Aerodynamics - this argument has got to be ar$e right? Look at Rossi for a great example. If it was for aerodynamics why would he have a huge furry shag pile race number on his hump??? Also i can’t see how a soft material can help as the air will compress it and move it at speed. Also this hump can only really be expected to help (if made from carbon fibre and very smooth) at speeds over 150 ish?
Safety - I’m sure many of you have been on track days or watched racing and the medics trying to put people on spinal boards. This hump is just another big hurdle to jump to maintain spinal stability after a crash…I just see it as plain dumb with having to use pillows and other devices to combat the ‘fashion’ hump. Surely motorcycle gear is for safety and having a flat but well protected back would be best???
To conclude I think these humps are simply fashion statements and don’t help at all! And to a point hinder the protectiveness after a crash!
For most its fashion, for the top riders its function. As correctly mentioned above, the humps are usually used to contain fluid with a connecting tube so that the rider can take some fluid on board when needed. Dr Costa, the MOTO GP main doctor, does not like the humps. Club racers were asked last year to go and get some stuff done at hospitals wearing their leathers, but only if they had a hump. I am sure there will be some medical facts coming out about them.
buffeting is from air getting into your leathers/gear through a loose neck or cuffs. Surely a hump has no bearing on this…maybe your previous suit fitted poorly or you had a 2 piece zip together?
Primarily they’re for aerodynamics on long straights. Without the hump, an area of low pressure is generated in that position, creating turbulence and therefore drag resulting in a slower bike down the straights. By adding the hump, the bike and rider theoretically form a “teardrop” shape so that the air flow opens and closes smoothly around the moving bike.
For a perfect example, look at the cyclists who do time trials, their helmet extends down their back, across their shoulder blades, generating a hump and eliminating the gap.
It is also true to say that the humps do create problems for medical teams during emergency situations as they make it difficult to lay any casualty flat on their back without straining the neck.
And they’re a pain in the arse on the road cause you can’t carry a rucksack
The buffeting is from the helmet and air disturbance flowing round the helmet and not the fitting of the leathers. The hump makes a difference to the channeling of the disurbed air and helps to stop neck pain when the helmet is buffeted. Or should I state that it makes a BIG difference to me on my 128 mile round trip to work and back based on my experience of both types of leathers humped/no hump.
I didnt buy my leathers because there was a hump on them and to be honest i have never ever noticed / felt a difference hump or no hump
It has been said that these should be removable to maybe a zip or velcro on the top so that you can take the wedge out in the case where you need to be strapped to a spinal board of laid flat on your back etc.
Even thought about sending my leathers off to get velcro or a zip put in mine, i know in the case of a big off i would want to be able to be laid completely flat.
Adamski/Stuts - Don’t believe the ar$e you read about the aerodynamics…(and even if you do believe it your 128 mile commute would only be helped by the hump at 150mph +)
If it was aerodynamic it would need to be made from a smooth hard material like the initial humps on leathers back in the early 80’s i think it was. They were fibreglass i do believe from memory. My point being that even if it was made from fibreglass/plastic/something smooth surey it has no use whatsover on the road as it merely poses a hinderence to the poor abulance service when the sunday hooners wearing them fall off and snap their necks?
I have a mini hump (very mini) on my leathers…i’m not biased because i think they look crap…i just think they should rid leathers of them because of the clear problems they cause trackside/road side post incident.
But please don’t go believing they are aerodynamic…next you’ll be telling me the tassled numbers on rossi’s hump are there to improve aerodynamics too.
I know they don’t make the bike/rider slippier through the airflow. As I said, the idea is to smooth the airflow around the bike/rider to reduce turbulence. If you reduce turbulence, you reduce drag, therefore higher speed. Obviously only useful in high speed/race situations and more of a liability on the road.
Why do you think cyclists in time trials use them if they have no benefit. Their top speed probably isn’t any more than 45/50mph?
The buffeting is from the helmet and air disturbance flowing round the helmet and not the fitting of the leathers. The hump makes a difference to the channeling of the disurbed air and helps to stop neck pain when the helmet is buffeted. Or should I state that it makes a BIG difference to me on my 128 mile round trip to work and back based on my experience of both types of leathers humped/no hump. 
