R 1200 ST Geometry

[bvaughan]

i ride an 1150 gs and rt. geometry is fine, bikes do just what i expect. am on a 1200st for a while. i don't get it; i really don't. the minimum turning radius is huge; the bike has this twitchy feel like if i gave it a little too much countersteer it'd collapse; can't seem to get in the i'm-in-control groove, even though i've got a couple thousand miles on it.

 

what's the point of the sport bike geometry in the first place? seems like the short yoke with little rake or trail gives a bike that's twitchy and no faster. the boy-racer look must have some functionality, but what is it? what'm i missing?

[russell_bynum]

It isn't Sport Bike Geometry.

 

Compared to my CBR600RR, the R1200ST handles like a Greyhound Bus.

 

The reduced weight and better riding position make the bike much more responsive and easier to corner. It makes good body position much easier, and it rewards good body position much more than the upright RT does.

 

The position is also much better for you, since it spreads your weight out to your feet, legs, back/abs, and butt instead of putting it all on your butt. And, since your spine is canted forwards, it can flex naturally to absorb bumps rather than compress like it does on the upright RT.

 

The downside is that it takes more physical effort to sit that way, so you probably can't go as long before you need to rest. Interestingly...what I've found, is that when I get tired riding a bike like the ST (Lisa has an R1100RS, which is very similar), I can get off for 10-15 minutes and I feel refreshed and ready to keep going. Once I get tired riding the RT, I'm going to be tired and sore the rest of the day.

 

I hadn't noticed any real difference in turning radius on the R1200ST...it made all the tight turns I needed it to make, but I'll freely admit that I didn't do any real testing on that, so I may be mistaken. It definitely turns tighter than my CBR600RR, though.

[bvaughan]

It isn't Sport Bike Geometry.The reduced weight and better riding position make the bike much more responsive and easier to corner.

That's part of what i don't get. i'm not arguing, i just don't get it. i sit like a chippy on the rt and can ride all day long. if the road gets rough i can put some pressure on the pegs and smooth out the ride. i'm not canyon carving or on the track so i don't need to hang off the tank, and my wrists never get sore. so what's better about the sport bike position? more basically, what is it about the sport bike design concept that has short twitchy rake? what purpose does that serve? and what's the actual kinesiology or ergonomics reason for the forward lean? and what is it about the sport bike concept that has the front fork and handlebar setup the opposite end of the spectrum from something like the gs? what is it about a short fork and clipons that is superior on the track?

[NakedRider]

It isn't Sport Bike Geometry.The reduced weight and better riding position make the bike much more responsive and easier to corner.

That's part of what i don't get. i'm not arguing, i just don't get it. i sit like a chippy on the rt and can ride all day long. if the road gets rough i can put some pressure on the pegs and smooth out the ride. i'm not canyon carving or on the track so i don't need to hang off the tank, and my wrists never get sore. so what's better about the sport bike position? more basically, what is it about the sport bike design concept that has short twitchy rake? what purpose does that serve? and what's the actual kinesiology or ergonomics reason for the forward lean? and what is it about the sport bike concept that has the front fork and handlebar setup the opposite end of the spectrum from something like the gs? what is it about a short fork and clipons that is superior on the track?

 

I've got an ST as well and they do handle differently than the other bikes that you are used to. Here are two things that will help - big time. Loosen your grip. Just let the bike go and you will feel it's tracking better. The other thing is to weight the inside bar when you turn. For some reason this REALLY matters on this bike. I'm trying to get used to this as well. On high speed sweepers it seems to do fine. Otherwise it feels like it always takes more work from me to keep it from twitching.

[russell_bynum]

i'm not canyon carving or on the track so i don't need to hang off the tank, and my wrists never get sore.

 

Ah. That last part is an indicator of what's wrong. You shouldn't have any "sore wrist" issues because you shouldn't have any weight on your hands. Read this to learn how to correctly sit on a bike like the ST.

 

Even at the track on my CBR (which has a far more agressive forward lean/folded up like a pretzel riding position than the R1200ST), I don't get sore wrists because I'm using the riding position from that post.

 

what is it about the sport bike design concept that has short twitchy rake? what purpose does that serve? and what's the actual kinesiology or ergonomics reason for the forward lean? and what is it about the sport bike concept that has the front fork and handlebar setup the opposite end of the spectrum from something like the gs? what is it about a short fork and clipons that is superior on the track?

 

Good question. I'm not positive, but here's what my understanding is...

 

All of that rake/trail stuff is about making the bike stable. i.e. making it resist direction changes. A sportbike is setup to be less stable so that it you don't have to spend as much effort overcoming that stability to make it change direction. If you go too far with that, you wind up with a bike that wants to headshake. Pretty much all racebikes have steering dampers to help with this, btw.

 

The wide bars of the GS give more leverage, which makes it easier to get the bike turned.

 

So...why not put wide bars on a sportbike? My only thought there is that wide is not as aerodynamic. Narrow clip-ons of a racebike put you in a more aerodynamic position, and that can be important, depending on the track. With the GS, speeds are much lower, so aerodynamics aren't an issue. Also, at a slower, tighter track, an upright bike like a GS can really do well, and doesn't give up much to the sportbikes even though the sportbikes are lighter and make more power.

 

The forward lean works because it balances your weight on your feet. In adition to letting your spine absorb shocks better (more on that later), it makes it easier to move around on the bike. That's not so important on a street bike, but on the track, it makes it much easier to slide from side to side for the corners.

 

Now...about the "your spine as a shock absorber" thing. Sure...when you see a bump coming, you can shift some weight to your feet to unload your butt and keep from sending that jolt into your spine. But you're hitting bumps all day long. Even the little ones like the seams in the pavement are transfered up into your spine. I think that this adds to the fatigue, and I believe that's why I'm less tired/sore after a day on a bike like the R1200ST than I am after the same number of hours on my RT...even though I get tired sooner and have to stop more often on the ST, I recover faster.

 

These are good questions...I'm not 100% on all of the answers, so hopefully we'll get some more people jumping onto the pile as well.

[Spinner]

The forward lean on a sport bike, combined with the peg location, affords easier shifting of position to control lean angle through turns. Similarly, it facilitates a good aerodynamic tuck on the straights. The narrow span of the grips is analogous to small steering wheels on sports cars - providing quicker, snappier steering inputs.

 

Combined with steeper rake angles which shorten the trail distance makes for what you describe as twitchy (others describe as responsive). These bikes are nimble and require little effort to steer (because of the smaller trail distance), so wider grip distance isn't required to get desired results.

 

In the end, if it doesn't work for you, it doesn't work. Pure sport bikes, while fun for a short excursions don't work for me. Similarly, my GT's ergos don't work for others.

[wilsons]

Could someone explain this concept of 'twitching'? I'm a little baffled on what thats refering too

[russell_bynum]

Could someone explain this concept of 'twitching'? I'm a little baffled on what thats refering to

 

Bikes with agressive steering geometry often feel like the slightest control input will result in a big change in direction. Where the RT takes a big countersteering push to get it turned, something like my CBR will change directions with MUCH less effort.

 

Likewise, wide bars can have the same impact since they increase the leverage. The first time I rode a GS, I weaved down to the road a bit at first because it took SOOO much less effort to turn than I was used to with the RT due to the wide bars.

[wilsons]

ohh okay, I was sort of on the right track but wasnt entirely sure.

 

One thing I definately notice is that depending on how my arms are bent during a turn, that effects the control of the bike (center of gravity), also if I'm sitting way back in the seat and I hit the twistie parts on RR HWY, I find myself moving up against the tank, and benting my arms more to gain the absolute best control of the bike.

[YamadogR1]

I have ridden thousands and thousands of miles on high performance sportbikes and I will try and pass on a few tips. Current rides are an 051200ST and an 04R1. What gets people in trouble sometimes on a sportbike are:

Relax, do not grip the bars in a death grip and lock your elbows. A sportier bike responds very quickly to your input whether that be the right input or wrong input. Go with the bike, do not fight against it. Let the bike do what it is engineered to do. Make your inputs as smooth as you can thus not disturbing the chassis as much. Ride on the balls of your feet in the corners and bumpy situations. Gives you the feel of what the bike is doing and uses your legs as shock absorbers. Compared to the R1 the ST is a big friendly comfortable bus.

[sardineone]

the bike has this twitchy feel

I'm going to assume the ST you rode wasn't setup properly for you as I'm having no problems with the handling of my ST. The demo I rode before my purchase almost turned me against the purchase for it's turning characteristics(anything but agile). I strongly suspect tire pressures & possibly shock setup. My previous bike (Triumph Speed Triple)is solidly in the vein of machine you are describing with very quick handling. It was stable as long as one supplies accurate and gentle control inputs. A real tool on mountain rodes. I've had no real problems adjusting to my ST's handling. I feel that both of these machines handle very well. My ST definately more composed at triple digit speeds. At the risk of restarting a previous thread, I have the quality feeling ESA suspension on my ST.

[bvaughan]

thanks for the input guys. i'm gonna check on the tire pressure, pay attention to back bend and weighting the handlebars, or not, and the other points.

 

still have some questions as to the design considerations. gonna do some research on that and get back to you with the results.

[sardineone]

As you research the ST, here's one point that I don't know the reason for. Most would assume that the front end of the R1200ST & RT are the same. Not so. The ST's has larger fork tubes and looks much like a GS Telelever.