Running Gear Headed Down The Sprocket DrivePosted: March 6, 2011
I’ve never given much thought to proper gearing. I’ve heard about it, but the most I really knew about the final drive ratio was that it was just another of many a brilliant way to screw up a perfectly good ride. I knew that changing sprockets could be used to manipulate the power delivery characteristics of the engine, add top speed to the detriment of low-end torque or sacrifice some off the top for more of that awesome arm-stretching pull down low. Want your bike to sound like an Osterizer going down the road but don’t have a 250? Bring that final gear ratio down for more of that “I’m so much faster and exponentially cooler than you” engine sound. Really gives that new $600 rip-roaring loud slip-on a ton of street cred. You’re wound up tight but get there quicker. You’re also shifting quite a bit more, because the gears are closer together at the top of the box. But be aware that you now only sound fast. Your engine is working harder and your bike’s maximum speed just took a nose dive below the need of that TRE you just bought off eBay.
Note: A Timing Retard Eliminator aka de-restrictor is a device designed to remove or circumvent the artificial top speed restriction to 186 mph imposed on Japanese-made sport bikes capable of going faster. This practice is known as the “Gentlemen’s Agreement” between the USA government and the four major Japanese manufacturers: Suzuki, Kawasaki, Yamaha, and Honda.
Want to pop those wheelies on your ‘Busa, but having a hard time getting it up? Drop a few teeth in the front and be ready for that Viagra moment!
It didn’t dawn on me when Ed Bargy addressed the issue and said that most stock sport bikes are not geared properly for the track. They are geared way too tall. You should be hitting red line in top gear somewhere on the track, usually that means the end of the longest straight. You should be using the upper three gears negotiating the track, since the gear ratios of the top gears are closer together, not as tall. This will enable you to stay in the optimal power band more easily and gear selection for any given corner is simplified since you run less of a chance of getting stuck between the choices of “lug ‘n bog” or “scream and bounce (off the rev limiter)” because your gears are too tall, meaning they are too far apart in the RPM range. Acceleration is also much better when you’re in the “sweet spot”, too. The sweet spot is the point in your engine’s power band where horsepower and torque are at their peak.
Blah… blah… blah… I listened, in that store-for-analysis-later semi-disinterested way, made a mental note of “each track usually has its own unique setup requirements for your bike”. I muse that this final drive ratio bit falls into the same category with dialing in proper suspension settings and tire selection. Who has the money for that? Not that this matters at my level. I’m still 16 seconds away from having to worry about stuff like this, or so is my conviction. For an anal retentive and recovering borderline-pathological perfectionist, I can be pretty blasé about some things. OK, I promise I’ll worry about it in 10 seconds.
I’ve forgotten all about gearing until I watched my onboard track videos. Good grief! The stuff you never knew you did wrong! Blaringly obvious! I shifted like I was tooling around on the back roads, stuck behind a gaggle of cruisers and worrying about my fuel economy! I short-shifted…. No, you can’t even call it that. I shifted so early, I had to pre-register the request with my transmission. No wonder I lost several runs on the straights, even when I didn’t forget to get on the gas coming out of a turn! I felt like I was going backwards in time when I was waiting for the bike to accelerate, it took so long for the engine “to kick in”. Shifting too soon in the RPM range and not being at full throttle are only two of reasons.
The third, it had finally sunk in, is my gearing. The words of Mr. Bargy came rushing back to me. All that information I didn’t think I needed just yet suddenly seemed a lot more important. And my bike wasn’t all that happy in the lower gears. Like I always have said, she doesn’t like to be in too tall a gear. Not that the S1000RR lugs, she just feels vibey and discontent. I can definitely feel when she is in “her range”. The buzz in the bars lessens; the bike seems to settle and is more responsive, like a cat readying herself to pounce, if that makes sense. She feels like she is on rails when you’re up in the RPM range and giving it throttle in the turns… not so much when you’re “coasting” through the corners at 5,000 RPM at quarter throttle singing la-dee-da-dee-da… it’s a beautiful day… whistling and thinking happy thoughts. Yup, I caught myself riding it like a girl out on a Sunday drive, not a care in the world and feeling fi-iiine. Gawd! I’m less of a Miss Daisy on the street. At least it seemed that way. Holy hell. I guess I was having so much fun, I forgot I was there for roadracing training, not for a stroll down the track in the beginner group.
I did watch the novice group and it was almost like they were going in slow motion. I saw one control rider going around the fast part of the track in standard street pose. You know, upright, kind of cockeyed on the bike, clutch hand resting on the upper thigh. Poor guy probably drew the short straw at that morning’s staff meeting. Bummer! And to think I almost signed up for the novice group because I thought I wouldn’t be able to keep a constructive pace in the intermediate group.
I also watched the expert group for a while. I mentioned to Mr. Slow how freaking fast they look. He nodded and said it was fun to watch these guys duke it out in the corners. I asked him that we must be crawling compared to them. He nodded in agreement: “Those guys look at you like you look at the novice group.” Wow! That’s kind of neat when you think about it. My first ever track day w/o instructors and class room sessions and I’m mid-pack in the mid-pack. That is freaking cool beans. For some reason I didn’t think I was “that fast” already.
Speed is a strange critter. Well, not speed… the perception of speed. When you are on the track you seem pretty fast to yourself. Of course you do, because you’re riding at the upper third of your skill range, or at least should be when you’re learning and concentrating on technique and being smooth, but still pushing boundaries and feeling for the limits. When you watch the POV video from that same session, you’re so embarrassingly slow, you only watch it alone, in the dark, behind a closed door. When you watch others go by who are riding at about the same speeds with comparable skill you think you’re out of your mind and can’t believe you’re actually out there doing the same. Yeah, baby!
What does this mean to me? I am at work studying the fine art of gearing selection with the help of Ed Bargy’s book “Introduction To Motorcycle Roadracing” and this handy little online tool called “Gearing Commander”. Stay tuned… this subject has the smell of walkthrough about it. I engage my brain this much while studying a subject matter, I have to put it in concise and organized form to remember it all and make sure that I have actually grasped the concept. For now, I better stick my nose back into the books and figure this thing out. I’m not going to Nashville to hit the Superspeedway just so I can do a little street riding around 6,000 RPM. I’m going to have this sorted. I already have to change my tires after every track weekend, and put the bike back into street trim. What’s adding two more sprockets to the task going hurt?
I really need a dedicated race bike… Nah! I’m the girl who wears knee pucks on the drag strip. I’m also the girl who rides her S1000RR 285 miles in full race gear just to hit the track. I wrestle drag bikes through the twisties and abuse supersports on the drag strip. Did I mention I am the first person in the world to do the entire BRP (Blue Ridge Parkway) end-to-end on a BMW S1000RR in second gear, observing the speed limit (more or less)? Why start and be normal now? =D