Honda CBR 250 Forum banner

1 - 20 of 54 Posts

·
Registered
Joined
·
3,527 Posts
Discussion Starter #1 (Edited)
Some of you may have given up on the other thread as it became argumentative but some good discussion on side winds has developed toward the end so I thought we could start a clean thread about the riding dynamics of cross winds. Side winds can move you off line in many different ways. By pushing the entire bike straight to the side. This is probably the only situation where increasing the total mass of the bike/ rider/ luggage will help. I believe other mechanisms of cross winds that actually cause the bike to steer will be more disruptive. Cross winds pushing on the side area of the bike/ rider/ luggage that is above the center of gravity of the roll axis will cause the bike to lean and actually turn off line. Worse yet, blowing the rider's head and torso to one side of an upright, yet comfy riding position, such as on the CBR250R, again makes the bike turn the wrong way. The next thing that probably happens is the rider will push back with their arms which applies a counter steering manuver to the handle bars which makes the bike lean the wrong way even further. All of this happens in a domino effect blowing you off line. Super Sport bikes with their ultra low and narrow clip on handle bars place the rider in a better position to resist all of this in the de facto riding postion they impart by lowering the rider's upper body, and so, the side wind center of pressure, by more firmly bracing the rider due to much more weight on the arms, and, by greatly reducing the leverage of unwanted counter steering commands because of the narrow bars. But who wants to ride in stop and go traffic or on a four hour highway trip in that position when you can have bars that let you sit up to get a better view of the car that is about to pull out in front of you from the side street, or, just to stretch out once in a while. Many of you may think it is dangerous or embarrassing to ride while laying on the tank but I feel very alert and safe on the CBR250R in this position and all of the perceived short commings of low power and light tires/ total mass, vanish when you do. The bike will roll on from 65 mph to 80 in order to pass with great ease because you are wasting less power to push forward through the air resistance. Also, it is my experience that the ill effects cross winds are completely negated. What I see with sidewinds while commuting on the highway is that when you lay on the tank, you accomplish two things. The center of pressure of the side area including the excellent faring, wheels, and your body, is lowered to the point that it is actually lower than the cg on the roll axis which causes the wind to push more on the bottom of the bike/ rider, than the top, forcing the bike to steer itself into the cross wind. It is an eerily magic sensation and very addictive. Also, the mass of your torso above the center of gravity on the roll axis is anchored to the tank so you don't get blown into leaning off of the bike the wrong way and you don't have to counter push on the wrong end of the bars to stabilize yourself. Honda did a great job designing the ergonomics of the tank shape. It is very comfortable to lay on and works perfectly in this position to take some weight off of the seat and arms for hours of riding comfort and provide a magic carpet ride that couldn't care less for cross winds.
 

·
Registered
Joined
·
62 Posts
Nice analysis Sendler. I have also noticed that cross-winds are no problem when you get down on the tank. On long rides I usually have the tank bag and it is in the perfect position to rest on automatically.
 

·
Registered
Joined
·
269 Posts
i gotta say i feel like a toolbag tucking in anywhere other than the track. i see squids tucked in on the highway doing all of 70 mph and i'm like "what are you doing???"
 

·
Registered
Joined
·
3,527 Posts
Discussion Starter #5
Already tucked

i gotta say i feel like a toolbag tucking in anywhere other than the track. i see squids tucked in on the highway doing all of 70 mph and i'm like "what are you doing???"
That's because you are already tucked behind the screen when you are sitting straight up.:D JUST KIDDING! That's a short joke. You know we are happy to have you here.
 

·
Registered
Joined
·
206 Posts
I have to say I spend 80% of my time tucked. The only reason I sit up is to air brake or so I can be seen better. Some say it is uncomfortable but if you slide your butt all the way back till it hits the passanger seat it should help with the lean. I bought this bike for MPG and this gets the job done better. You will find most of those riders who complain about there MPG are not tucking much. Also if you hit the sweet spot it kills alot of the wind and motor noise and keeps some of the rain off you.
What do I look like when I tuck? I dont know I cant see my self. What do others think I look like? I dont know they are at the gas station.:cool:
 

·
Registered
Joined
·
269 Posts
That's because you are already tucked behind the screen when you are sitting straight up.:D JUST KIDDING! That's a short joke. You know we are happy to have you here.
hey there are a lot of short people on this forum! together we might make one normal sized person and kick your azz!

when i've tucked in on the highway it's hard for me to see what's around me and keep track of the cars. i can def see where you can eliminate some resistance and get better fuel economy.
 

·
Registered
Joined
·
14 Posts
I intentionally do not ride on the interstate, but occasionally I must. So if I need the extra quickness or top end speed - I tuck. The tank bag makes it so I can't get fully tucked. Without the tank bag and when I am riding with my buddies I am usually fully tucked the whole time, the next smallest bikes in the group are a couple Triumph Street Triples.

As a side note, when I bought my HJC CL-16 Helmet there was a sticker in the packaging that says:

WARNING

Visual impairment hazard

DEATH OR SERIOUS
INJURY CAN RESULT
DO NOT RIDE IN THE TUCKED
OR CROUCHED POSITION

Complete with two pictures:

One of a rider in the tucked position and a big red X,
One of a rider sitting up with a big green check mark

I carefully removed the sticker from the packaging and attached it to my helmet.

I wear this helmet for track days so when the instructor tells me I am not tucked enough I tell him I don't want to die and point at the sticker.
 

·
Registered
Joined
·
14 Posts
Hi-Vis? I would like to take credit but it is just the reflection from the table.
 

·
Registered
Joined
·
4,996 Posts
All sounds very complicated..
Ride with your feet.. thats what puts weight where its needed.

And do rider training courses.. lots of them.
 

·
Registered
Joined
·
3,527 Posts
Discussion Starter #17
Miller

+1 Just go out and ride! :D
You guys didn't like my long dissertation? Too much of a Dennis Miller effect going on I guess where I'm the only one that knows what the heck I was talking about. I just found it interesting to try and figure out how a bike like this can actually lean into each gust of cross wind which is what I have observed.
 

·
Registered
Joined
·
4,996 Posts
You guys didn't like my long dissertation? Too much of a Dennis Miller effect going on I guess where I'm the only one that knows what the heck I was talking about. I just found it interesting to try and figure out how a bike like this can actually lean into each gust of cross wind which is what I have observed.
Its a motorcycle.. gyroscopic forces that you dont need to worry about.. Mr Honda has done all that homework.

all you have to remember is that the footpegs are between the axles.. use them to your advantage.
 

·
Registered
Joined
·
354 Posts
The Honda website somewhere mentions that the fairing design actually helps in cornering when you are leaned. I thought it was to help you out of a turn, a lifting force. This may have something to do with what Sendler wrote about.
 
1 - 20 of 54 Posts
Top