Riding 125/250 GP Bikes

[Paul900rr]

I understand there’s a power to weight ratio difference between GP bikes compared to bigger 600cc bikes and the like. In a recent conversation, I was told that GP lines are different than a “regular” line. That puzzled me. I’m not sure, but I’m assuming the lines are different because of corner speed. Why are the lines different and how do they differ?

[Akshun]

Like riding the pace, lil braking, riding on the "edge". Precision of proper line varies with speed.

At a more relaxed pace (easier on a larger bike with more torque), placing the bike nearly anywhere within your lane can be an acceptable line. However, as your speed increases, your margin of error lessens and the acceptable line becomes progressively narrower.

At a faster pace, the proper line on critical portions of the track is squeezed to mere inches, or perhaps even fractions of an inch, wide, making the lines more precise.

This faster pace is needed for the smaller GP bike to achieve good laps times.. or so I'm told

[Fawaz]

I've never ridden a 125/250 but the lines you use when you are on a 1000 are very different from what you use on a 600. So i could see that being true.

[franz131]

Momentum and corner speed are critical with a GP bike, even a stock 600 has massive low-end torque compared to a 250. The weight and chassis geometry also rewards high corner speeds.

With this in mind, your approach to every element on the track is different than a street-based bike.

[john bickle]

The line doesn't really change. ON a big bike you have so much HP you get lazy and dive for the apex sooner because you have the power coming out. The speed changes more then anything. You can not carry the same corner speed on a 600 as you can on a 125. You can try!
Mosport for example, corner 8 is a pretty hard braking corner for a 600/1000. In 1997 I learned to take it on my 125 in 6 gear not letting off! According to my gearbox ratios and RPM I was about 230 KPH.My lap times dropped incredibly. The fastest lap on a big bike at Mosport is only about 10 second faster then "the" fastest lap on a 125.
600/1000 riders tend to square corners off. To some extent if you are using the slipper clutch and down shifting properly that is acceptable these days.
Also the bikes are lighter. So "any" body movement or changes can throw you down the road. So setting your line and completing it are paramount.Changing line mid corner is a gamble mostly because you have no room for error because of entry and mid corner speeds. Thus the reason a good GP rider looks far ahead.
Your weight to HP ratio is huge!! Depending who you talk to it's around 1 HP for 7-10 pounds of weight. So someone that ways, 70 pounds riding against a 170 pound rider has a 7-10 HP advantage. But the lighter person can also brake later and carry more mid corner speed resulting in greater exit speed. In 1995-96 when Moto Liberty Sponsored the AMA class, I was border line anorexic!!
But a 600 is pretty much a 250 GP bike on steroids! So the faster you get the more the GP style plays a part.
So rider smooth and tidy and you won't have to change.
Now all this changes once you have to ride to protect a line!

John Bickle
11 years of 250 GP riding
14 years of 125 GP riding
5 years of riding diesels with Turn 2! [the Ninja 600 is pretty cool,for a diesel]

[Metastable]

It's physics... the lighter the bike, the less amount of lateral Gs (centrifugal force) are created for a given speed. Therefore, you can take a corner faster on a lighter bike. It's that simple, really. Bike did a small article a while back and basically said that for a given corner that a Goldwing took at 100mph a GP bike could take that same corner at 150mph and produce THE SAME centrifugal force.

EDIT -> Unless Franz is riding it...I hear... bikes go faster for (as Splinto put it) "old guys"

[franz131]

EDIT -> Unless Franz is riding it...I hear... bikes go faster for (as Splinto put it) "old guys"

That's right, and don't you forget it.

[john bickle]

EDIT -> Unless Franz is riding it...I hear... bikes go faster for (as Splinto put it) "old guys"

Hey, In order to be old and wise, you first have to be young and stupid!

[rsilk]

Hey, In order to be old and wise, you first have to be young and stupid!

It's the wisdom part I'm having trouble with.

/r

[MaSheena]

I LOVE my TZ125! In fact, I just upgraded from a '98 to a '07.
There are certain ups and downs to GP riding. I really enjoy futzing with jetting tuning etc. For me, it is a necessary part of the riding experience... like a 'zen' with your machine. Others like to just hit the button and go.
I also, after many years of racing, am a firm believer that riding a little bike makes you a better rider. Yes it is horribly frustrating having a 600 or 1000 squirt past you on the front straight at 'bogie only to grab a handful of brake into T1 and T2 (the 125 only requires a minor throttle adjustment and a slight tap of the front brakes for T1) but the exit of T2 through T4 is soild acceleration. Where a 600 or 1000 is checking up for T4 the 125 is pinned, grabbing gears and making some serious ground on the larger HP, and heavier machine. If you play your cards right, you don't loose much ground uphill on the way to T5 and can have them back entering in on brakes. As Bickle said, you have to be dedicated on the gp...there is no room for a lazy corner!
Emerson Connor is a great example. Many of you would have had him ride around the outside of you at Calabogie on his RS125 (2.12's). He will be on a larger machine next year and will undoubtably utilize his GP experience to get even faster, very fast.

[Paul900rr]

Ahhh Bogie... Good times there. Thank you all for the good info.

[Tonto]

As many have already said (including BIC), riding a 125 GP is an experience unto itself. I can ride a bike pretty fast, but for the life of me riding my kids RS125 is a bi***! These are the most unforgiving bikes ever made. If you are 500rpm out of the sweetspot at any point on the track the bike just shuts down- no 'don't worry, I'll forgive you", no "I'll let you get way with this laziness just this one time"- nothing; it just shuts down, no power. It will however reward you like no other bike if you treat it right. Once it hits the power, hang on- you'll feel like you've been shot out of a cannon! A stock Honda RS 125 is 158lbs dry (that's right 158lbs) and has 35+- hp at 12000 rpms. That is some crazy hp to weight ratio. It does mean however that when you are on the track with some lazy SS riders that like to coast through the corners only to hammer it once the bike is vertical again, that you become very frustrated. Either that or you take a wide line to keep your speed up and just blow by them in the corners. As has been said- NOTHING corners like a GP bike! That is probably why it is common knowledge that the 125 and 250 GP bikes are the tools of choice to train young roadracers. By young, I mean 10, 11 and 12 year olds, not 20 somethings. By the time these kids can reach the ground on an SS, they have more knowledge about how to make a bike go fast (and more importantly, how to keep it fast) than most of us can ever hope to acquire. Trace the history of most of the fastest riders in the world and you'll probably find that they came up through the GP ranks. No bike will reward you more for perfect inputs, or cut you down for sloppy inputs than a 125 GP bike.
Make no mistake about it folks, these are by no means 'toys'. Oh, and by the way they cost significantly more than a stock 600 so they are not 'the cheap way' to get into the game.

Tonto

[minifig-phil]

If you haven't ridden a 250 yet you should try it! Nothing compares to a true GP bike.
I have only ridden a 125 once and it felt like riding a bicycle to me with the way it corners. But a well tuned 250 is another story. My ex Tripodi 1990 TZ250 with the long rod motor made 91hp and weighed 197 lbs and let me tell you there wasn't a 600 I rode that came out of a corner as hard as it did. Now having a newer V twin TZ250 with a lot more bottom end than the old RS and '90TZ I had makes it so much easier to ride.
I find the GP bikes get much easier to ride the harder you ride them. There is nothing like it.
You can break so deep and just flick it into corners and know it will go where you point it. If the gearing and jetting is good it will keep upto a 600 on the exit no problem.
At Cayuga 1000's go by you like your standing still on the front straight and pull out a huge lead and then you shift into 6th gear at the same time they get on the breaks for turn 1 as you fly by them is just totally awesome!!

The newr stuff (Vtwins) are so much easy to keep runing too they aren't as tempermental as the older RS or Reverse TZ I rode in the past.

[steph1000]

i like my fat *** 1000.......its fun parking and picnicking in corners

[mihnea]

at cayuga 1000's go by you like your standing still on the front straight and pull out a huge lead and then you shift into 6th gear at the same time they get on the breaks for turn 1 as you fly by them is just totally awesome!!

i want!!!