RTrev Posted July 12, 2008 Posted July 12, 2008 I don't have access to a racetrack, at least that I'm aware of. Does anybody happen to know what the actual top speed of this bike is, and what the top speed in each gear is at redline? This isn't critical, it's just a matter of curiosity. It's become obvious to me that even the top speed in 2nd gear must be in the "license revocation" range, so I'm guessing that trying to find the top speed of 3rd gear would put me into the "just stand him up and shoot him" range. And there's three more gears to go. Thanks, Bob
ShovelStrokeEd Posted July 12, 2008 Posted July 12, 2008 Make up your own spread sheet and figure it out. The gearing specifications are on BMW's web site. At 8K RPM, maximum speed in each gear will be: First..........52 Second.........75 Third..........94 Fourth.........115 Fifth..........132 Sixth..........146 might be HP limited to around 143 The above calculated values reflect a realistic aspect ratio on a 180/55-17 of around 53 instead of 55. Real world calculation based on GPS measured speeds vs calculated speeds.
GregB Posted July 12, 2008 Posted July 12, 2008 Even though I would prefer 6th gear to be a bit higher for relaxed high speed cruising, the bike is unlikely to go much faster in 6th than 5th. I'm guessing it will just get to redline in 5th and then would probably hold that speed in 6th. The looooong front straight at Willow Springs Raceway won't quite let you get to redline in 5th, so it is unlikely you would find topspeed even on a track. With the torque curve on the RT engine you are mostly making noise at the last 10% of the rpm range anyway. The bike pulls just as well or better at 6-7,000rpm.
RTrev Posted July 12, 2008 Author Posted July 12, 2008 Even though I would prefer 6th gear to be a bit higher for relaxed high speed cruising, the bike is unlikely to go much faster in 6th than 5th. I'm guessing it will just get to redline in 5th and then would probably hold that speed in 6th. What is the lowest speed you feel comfortable using 6th gear? For me, now, it's about 65. Below that and I'm never sure if I'm lugging the engine or just feeling the normal "big twin" power pulse effect. I've never had a big twin before, and the biggest bike I'd ridden prior to this was a Suzuki 750 in-line four. The looooong front straight at Willow Springs Raceway won't quite let you get to redline in 5th, so it is unlikely you would find topspeed even on a track. With the torque curve on the RT engine you are mostly making noise at the last 10% of the rpm range anyway. The bike pulls just as well or better at 6-7,000rpm. I guess Bonneville would be the only place to really find out, eh? Thanks guys!
TomfromMD Posted July 12, 2008 Posted July 12, 2008 My spreadsheet gives figures virtually the same as Ed's. Regarding actual top speed, (IIRC) Motorcycle Consumer News recorded 136 mph as the maximum when testing an '05 RT. Tom
RTrev Posted July 12, 2008 Author Posted July 12, 2008 My spreadsheet gives figures virtually the same as Ed's. Regarding actual top speed, (IIRC) Motorcycle Consumer News recorded 136 mph as the maximum when testing an '05 RT. Tom Thanks Tom. Am I correct in thinking that the '08 should be a tad faster, having been lightened and bumped up to 110 HP? Seems like a figure of around 140 would be reasonable to assume?
GregB Posted July 12, 2008 Posted July 12, 2008 "Lightened and bumped up to 110 HP" was done with the R1200RT that came out as a 2005 model. I believe that the only engine tuning change for R models in 2008 was with the GS models. That change got them a bit closer to RT specs. They may have sacrificed a bit of low end torque to do that.
ShovelStrokeEd Posted July 12, 2008 Posted July 12, 2008 Trev, Weight has virtually nothing to do with top speed, it is all about HP and aerodynamic drag. The HP required to overcome aerodynamic drag increases as the cube of the change in speed so, given equal drag on both bikes, 10 HP is going to make a minuscule difference in top speed. Just to run some hypothetical numbers, let's say the top speed is 140, HP limited at 100 HP. At 110HP, you would get all the way to 144.5 mph. It would take 23 more HP to make it to 150 and to get to where my Blackbird will go would require 198 HP, and that is rear wheel HP, not crank.
RTrev Posted July 12, 2008 Author Posted July 12, 2008 Ah, good point.. weight wouldn't make much difference. I didn't know about that cubed rule, though.. interesting the things one learns here. Thanks! I did a quick search on the Blackbird, and it looks pretty aerodynamic alright. I guess the RT would be like a barn door in comparison, eh?
ShovelStrokeEd Posted July 12, 2008 Posted July 12, 2008 Yep, it is pretty slippery. Does that speed with only about 140 rear wheel HP. Of course, I always adhere to speed limits and have never tested that on the street. The Hayabusa does even better, aerodynamically, thanks to the hump behind the seat.
Firefight911 Posted July 12, 2008 Posted July 12, 2008 I guess Bonneville would be the only place to really find out, eh? Thanks guys! What's that you say???????? This was on bad salt conditions and with noticeable wheel spin in 6th gear!
TomfromMD Posted July 12, 2008 Posted July 12, 2008 As an aside, while BMW quotes the RT's wet weight as something like 570 lbs., the motorcycle mags were weighing the bike at 625~630 lbs. Even allowing for 25 pounds for the saddlebags, BMW still seems to be about 30 pounds optimistic. Incidentally, the more I ride mine, the happier I am with the gear ratios - with the exception of 1st which could be about 15% lower. Tom
RTrev Posted July 12, 2008 Author Posted July 12, 2008 I guess Bonneville would be the only place to really find out, eh? Thanks guys! What's that you say???????? This was on bad salt conditions and with noticeable wheel spin in 6th gear! LOL! I should have known.. someone here had already tried it! Seems pretty respectable given wheelspin in 6th gear.. something which had never even occurred to be as being possible.
motoguy128 Posted July 12, 2008 Posted July 12, 2008 Even though I would prefer 6th gear to be a bit higher for relaxed high speed cruising, the bike is unlikely to go much faster in 6th than 5th. I'm guessing it will just get to redline in 5th and then would probably hold that speed in 6th. The looooong front straight at Willow Springs Raceway won't quite let you get to redline in 5th, so it is unlikely you would find topspeed even on a track. With the torque curve on the RT engine you are mostly making noise at the last 10% of the rpm range anyway. The bike pulls just as well or better at 6-7,000rpm. That's been my expereince, there's not much left in 6th than 5th. As for the last 1000 RPM, although the power curve is falling off, due to mechanical advantage (more RPM's), you will accelerate harder form 7000-8000 than from 6000-7000 in most cases, so best acceleration normally is shifting near redline, especially in 1st, 2nd & 3rd.
Dave_zoom_zoom Posted July 13, 2008 Posted July 13, 2008 I don't have access to a racetrack, at least that I'm aware of. Does anybody happen to know what the actual top speed of this bike is, and what the top speed in each gear is at redline? This isn't critical, it's just a matter of curiosity. It's become obvious to me that even the top speed in 2nd gear must be in the "license revocation" range, so I'm guessing that trying to find the top speed of 3rd gear would put me into the "just stand him up and shoot him" range. And there's three more gears to go. Thanks, Bob Wellll- With my 06 R1200RT I have found the following- On as flat a stretch of isolated pavement as I can find, in the cool of the morning and the winds are still, with side bags off, wind screen down, tire press. at max.,at a modest elevation, & Im tucked in tight, I have experienced the following--- Please note this is after all bills have been paid & my guardian angel & I have had a little talk. In 5th gear I hit the rev. limiter. In 6th gear I can just touch 240KPH. This is on a there & back run. No cheating. Actual speed is probably what others are saying. I'm sure no two bikes will be EXACTLY the same. If you are not feeling really good about doing it, PLEASE don't! Hope that helps. Dave
ShovelStrokeEd Posted July 13, 2008 Posted July 13, 2008 Given the standard 6-8% optimism of the BMW speedometer, that sounds about right. Elevation, or equally important, temperature, air density and humidity, can account for substantial variations.
Motodan Posted July 13, 2008 Posted July 13, 2008 My '08 RT's speeometer is within 1/2 MPH of GPS reading....I too was surprised.
RTrev Posted July 13, 2008 Author Posted July 13, 2008 Thanks Dave. The only time I've ever gone that fast, there were attractive flight attendants serving me cocktails! I don't suppose that's programmed in to the RT computer though. I think I'll just take your word for it! I never go over 80 anyway. I was mostly just curious what this beast could do. Thanks again!
motoguy128 Posted July 13, 2008 Posted July 13, 2008 My '08 RT's speeometer is within 1/2 MPH of GPS reading....I too was surprised. With a new set of tires, I also found my speedo was only 1 mph off @ 70mph. Of course, as the tire wears, it will get far more optimistic.
RTrev Posted July 13, 2008 Author Posted July 13, 2008 I gather that GPS speed measurements are consistent and accurate? Amazing technology, at least to a caveman like me.
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