Tire pressure vs. ride quality vs. fuel economy - Honda CBR500R Forum : CB500F and CB500X Forums
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post #1 of 40 (permalink) Old 06-07-2018, 10:01 AM Thread Starter
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Tire pressure vs. ride quality vs. fuel economy

I'm finding the ride on my CBR kind of harsh. I think it is partly due to the shock being set up for heavier riders, (I'm 175) and partly due to the high pressure in the rear tire.

Honda recommends 42 psi on my 2015, whether I have a passenger or not. That seems high, and also strange that it would be the same with or without a passenger. Was it done that way for Honda to be able to promote the highest possible fuel economy. Or were they just trying to pick a value to suit heavy riders while keeping it simple? I would think mid-high 30s to be more reasonable.

Has anyone here tried it? If so, what was the result on your fuel economy?

I tried it on my KLR, increasing from the recommended mid-30s to 40 gave an extra 1-2 mpg. The suspension on that bike was so plush I didn't notice any difference in ride quality. However, I did crash when the Kenda rear tire suddenly let go while I was leaned way over. The peg was scraping hard, so it may or may not have been the high pressure that made the difference. (Yep, it was dumb)

Running lower pressure in the rear would also increase the size of the contact patch and improve handling. Racers routinely run much less pressure, in the 20s, if I recall correctly.

On a side note, the bike didn't come with any tools for adjusting the rear shock. I need to find or make a tool for that. I haven't looked into whether the rear shock's damping can be lightened up. (I'm assuming not)


-Jeremy
2019 Kawasaki Versys 1000 SE LT+

Last edited by Smaug; 06-07-2018 at 10:08 AM.
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post #2 of 40 (permalink) Old 06-07-2018, 10:45 AM
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Quote:
Originally Posted by Smaug View Post
I'm finding the ride on my CBR kind of harsh. I think it is partly due to the shock being set up for heavier riders, (I'm 175) and partly due to the high pressure in the rear tire.

Honda recommends 42 psi on my 2015, whether I have a passenger or not. That seems high, and also strange that it would be the same with or without a passenger. Was it done that way for Honda to be able to promote the highest possible fuel economy. Or were they just trying to pick a value to suit heavy riders while keeping it simple? I would think mid-high 30s to be more reasonable.

Has anyone here tried it? If so, what was the result on your fuel economy?

I tried it on my KLR, increasing from the recommended mid-30s to 40 gave an extra 1-2 mpg. The suspension on that bike was so plush I didn't notice any difference in ride quality. However, I did crash when the Kenda rear tire suddenly let go while I was leaned way over. The peg was scraping hard, so it may or may not have been the high pressure that made the difference. (Yep, it was dumb)

Running lower pressure in the rear would also increase the size of the contact patch and improve handling. Racers routinely run much less pressure, in the 20s, if I recall correctly.

On a side note, the bike didn't come with any tools for adjusting the rear shock. I need to find or make a tool for that. I haven't looked into whether the rear shock's damping can be lightened up. (I'm assuming not)

This seems to be the pressure that all the bikes use ,big or small, it seems mad but there you go.


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post #3 of 40 (permalink) Old 06-07-2018, 01:53 PM
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I'm curious about that too. From what I've read these bikes seem to have been set up for a 70Kg rider. Ad to that the fact that most reviewers (ie magazines and enthusiast websites) claim the suspension on the 500s is too soft. My experience on the roads here in Topeka is almost the opposite. I really need to pay attention on some stretches and lift my butt off the seat slightly or I'll get bucked pretty badly when I hit them. I've set my front pre load to around 30 mm but haven't been able to touch the rear yet since I don't have the spanner. I expect I'll add 2 or even 3 notches. I'm pretty light at 175 lbs. with riding gear but I do ride somewhat aggressively.
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post #4 of 40 (permalink) Old 06-07-2018, 06:07 PM
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Honda sells the spanner for the rear shock adjustment, but it is a common Honda size, but here are the tools that the rest of the world gets:
https://www.cheapcycleparts.com/oemp...6c9a5319/tools


You need #7 and the handle #14, but I'd buy the spark plug wrench also (#12) becasue it looks a bit different from those I have.
https://www.ebay.com/sch/i.html?_fro...LH_TitleDesc=0


It comes with a built-in elbow for off-center operation.


Ride safely,
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post #5 of 40 (permalink) Old 06-07-2018, 08:44 PM
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I felt the same way at first. I ran my tires at lower pressure and that resulted in high speed wobble. Scary stuff. As soon as I put the pressure back up, no more high speed wobble. I now keep my tires at 36/40 with preload set at 8. I've lost some weight so I'm thinking of adjusting rear preload down to 7 or 6.

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Male, 44yrs, 180lbs, 5'9", '14 (RWB), 22k miles, Bridgestone BT023, Vortex V3 kit, Rotella T6, KN-204 filter, 87 Octane, Maxima Chain Wax, Puig 6479W windscreen, clear signal lenses, Fork Preload caps, T-Rex spools, Radiator guard, Shorty adjustable levers, Fork stem RAM mount/USB port, red/black alum grips, 300R Rear tire hugger, Rear seat cowl, LED engine/undertail lights w/RF remote, LED position light, Sea level, city commuter, spirited rider, turn my own wrenches.
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post #6 of 40 (permalink) Old 06-08-2018, 01:26 AM Thread Starter
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Originally Posted by ExTex View Post
Honda sells the spanner for the rear shock adjustment, but it is a common Honda size, but here are the tools that the rest of the world gets:
https://www.cheapcycleparts.com/oemp...6c9a5319/tools


You need #7 and the handle #14, but I'd buy the spark plug wrench also (#12) becasue it looks a bit different from those I have.
https://www.ebay.com/sch/i.html?_fro...LH_TitleDesc=0


It comes with a built-in elbow for off-center operation.
Ordered, thanks. (I used hondaparts-direct.com; better pricing, even with higher shipping, and they had the sparkplug socket in stock too)

-Jeremy
2019 Kawasaki Versys 1000 SE LT+
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post #7 of 40 (permalink) Old 06-08-2018, 01:28 AM Thread Starter
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I felt the same way at first. I ran my tires at lower pressure and that resulted in high speed wobble. Scary stuff. As soon as I put the pressure back up, no more high speed wobble. I now keep my tires at 36/40 with preload set at 8. I've lost some weight so I'm thinking of adjusting rear preload down to 7 or 6.
How low did you have it when it wobbled? (because 40 is still a bit low)

I was thinking of about 38...

I'm wondering if it has something to do with the link-type rear suspension on this bike. On my other recent bikes, they all had a more primitive suspension, where the rear shock(s) went straight up to the back of the bike. This bike has the shock in the middle, actuated through a link, so that maybe the load is applied more from the center of the bike instead of the rear?

-Jeremy
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post #8 of 40 (permalink) Old 06-08-2018, 01:51 AM
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How low did you have it when it wobbled? (because 40 is still a bit low)

I was thinking of about 38...

I'm wondering if it has something to do with the link-type rear suspension on this bike. On my other recent bikes, they all had a more primitive suspension, where the rear shock(s) went straight up to the back of the bike. This bike has the shock in the middle, actuated through a link, so that maybe the load is applied more from the center of the bike instead of the rear?
I don't remember the actual pressure numbers. I think I had it at 32/34 or maybe 34/36. I do remember that bumping up to 36/40 cured the wobble. I ran at 38/42 for a long time after adjusting the rear preload and it felt good on the stock tires, but after switching to the Bridgestone 023's the rear felt better at 40.

Sent from my ONEPLUS A3000 using Tapatalk

Male, 44yrs, 180lbs, 5'9", '14 (RWB), 22k miles, Bridgestone BT023, Vortex V3 kit, Rotella T6, KN-204 filter, 87 Octane, Maxima Chain Wax, Puig 6479W windscreen, clear signal lenses, Fork Preload caps, T-Rex spools, Radiator guard, Shorty adjustable levers, Fork stem RAM mount/USB port, red/black alum grips, 300R Rear tire hugger, Rear seat cowl, LED engine/undertail lights w/RF remote, LED position light, Sea level, city commuter, spirited rider, turn my own wrenches.
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post #9 of 40 (permalink) Old 06-08-2018, 02:55 AM
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Wait a sec, those tools are suppose to be included in the kit with the bike? I only got an allen wrench, a fuse puller and a piece of foam in mine. Even my Suzuki GZ250 had more stuff in the bag come to think of it.
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post #10 of 40 (permalink) Old 06-08-2018, 07:37 AM
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In my opinion
Tires
I currently have Dunlop Road smart III's and run 33psi front and rear, no problems, no shake, and they corner great. Just for reference my RC390 manual states recommended psi front and rear at 29psi, I run 28 psi front and rear. My Tuono manual states 33 psi front and 36 rear, I run 31psi front and 31psi rear. I ride strictly in the mountains on very curvy roads with grip being my number one concern, mileage is whatever I get. My settings are from me trying different psi's and I check them before each ride.

Suspension
First item I replace on a new bike is the suspension. My CBF has front fork race tech internals and a Ohlin's rear shock, My KTM also has a Ohlin's rear shock and a Andreani cartridge kit in the front. My Aprilia is the first bike that I have done nothing to the suspension except have it serviced this winter as manual recommends servicing at 12,000 miles. I take all my suspension work to GMD Computrack in Fairmount Georgia. If you can afford it, find a suspension shop and have them set-up your bike.

Just my opinion
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