troop
Well-known member
18-20 psi
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I’m getting frustrated with the belt vibration - any ideas to help?
- Thread starter Wrongway
- Start date
18-20 psi
Poppie65
Active member
We had the Altimax installed, but my impression is that it is not a problem with the tire per se so much as the tire size. Ours is 215/60 R15, which is smaller in diameter than the OEM Kenda, and further feel that the source of the vibration is in the load vs RPM range.
That said, belt tension is roughly 250 and tire pressure is 21 psi, which is down from 29 when it was installed.
That said, belt tension is roughly 250 and tire pressure is 21 psi, which is down from 29 when it was installed.
Thanks for your impression - I was just wondering about the tire itself being a source of these concerns; and since many running a/mkt tires still do seem to run slightly higher than ideal pressures, which can induce 'vibrations', particularly at certain revs/speeds &/or on certain road surfaces (funnily enough, when that sorta vibration happens, it's usually most evident at around 70 - 80 mph!!
), if their chosen pressures might be playing a part in all this?? :dontknow: You can see my earlier post on the pressures tho, so I won't say any more on that. 
However, are you sure about that bit?? :dontknow:
If you used a tire size calculator to work that out, it's not necessarily correct - those calculators will only show/use the 'nominal size' for the entered tire data; and for most I've tried, their results almost always do not even exactly match the OEM tire's actual size vs that printed on the Kenda's sidewall; plus, there's a distinct possibility that the Altimax is also a tire that doesn't exactly match the 'nominal size' from those comparison chart results, so any tire size calculator comparison may be juuust a little misleading at best! And IIRC, most here report that their speedo's became more accurate after installing Altimax tires (altho which size Altimax they've installed may be also play a part there??) but if that's the case, then like many others have found, your Altimax may well have a LARGER rolling diameter and so do fewer 'Revs per Mile' than the OEM Kenda, making the speedo show a speed that's a little closer to accurate and your 'true speed'!
Even if you don't/can't go to the manufacturer's details & look at their 'Revs per mile' spec's (& not their rolling dia info, cos some manufacturers include the tread layers in their published data; while others use the nominal carcass size; and there are even some manufacturers who seemingly pull a figure outta the air or someone's nether regions for that sort of detail! :cus: ) to confirm that there actually is a size difference; and if there is, that the slightly narrower Altimax with a higher profile IS actually smaller in diameter?!? :dontknow:
Or - Do you run a GPS at all? If so, did your Speedo become EVEN MORE inaccurate & read even faster speeds than your true speed when compared to the GPS after you installed the Altimax, or did it start displaying speeds a little closer to that reported by the GPS? Using your smartphone & any app/GPS calculation it can do for this sort of speed comparison is better than nothing, but unlike most dedicated GPS units, most phone GPS capabilities aren't really up to reporting speeds all that accurately; so your smartphone might provide a reasonable indication, or maybe not?! :dontknow:
It's all interesting stuff, but it's quite hard to do any real comparisons via posts on a Forum - still, any detail you can provide helps! Thanks. :thumbup:
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Peacekeeper6
Member
I lowered my belt tension from the factory 210 lbs (measured on the ground) to about 150-160 with the Krikit gauge. I also installed the high-quality Lamonster IPS Belt Tensioner.
I used to have such a wicked vibration above 65 mph. After lowering the belt tension and installing the tensioner, the vibrations were GONE. Cruising above 65 mph is now A LOT more comfortable and pleasurable.
I used to have such a wicked vibration above 65 mph. After lowering the belt tension and installing the tensioner, the vibrations were GONE. Cruising above 65 mph is now A LOT more comfortable and pleasurable.
BajaRon
Well-known member
Poppie65
Active member
Thank you sir, I wrote my note backwards didn't I. This chart illustrates (to me anyway) the theory that the rpm range of 3200-3500 moved down into the speed of 65-70 mph in 6th gear, where with the smaller tire that rpm range would be found at a higher speed where most people aren't typically riding in.
Hope I said all that correctly this time.
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Poppie65
Active member
Hi Peter, sorry for the slow response, it's been a busy week. You may notice that I responded to the tire size rpms per mile chart that Ron shared which I think answers some of your questions.
I did install a GPS on the bike and confirmed that the speedometer is much more accurate now with the larger tire. And, while I really don't like being cynical, I don't think it's unreasonable for an engineer to install a work around in manner of smaller rear tire. If my theory is remotely correct about the RPM range then the smaller tire was a very simple "fix".
I did install a GPS on the bike and confirmed that the speedometer is much more accurate now with the larger tire. And, while I really don't like being cynical, I don't think it's unreasonable for an engineer to install a work around in manner of smaller rear tire. If my theory is remotely correct about the RPM range then the smaller tire was a very simple "fix".
That's a fair enough assumption. However, my reasoning for thinking that it's 'something other than the tire &/or its size per se' is because of the really significant number of other Spyder Owners who have fitted the very same tires &/or quite a few others in the same sort of size range who ALL report a LESSENING of the vibrations they experience; albeit admittedly, they are not all who already have what's been widely recognised as a 'belt tension related' vibration.
So for me, your 'the tire itself' theory falls somewhat flat because there's only 'a few' who happen to run the same type of tire (& the same size too?? :dontknow: ) who are reporting these continuing vibration issues, while what appears to be the majority report otherwise. So while the 'maybe it's the tire' part of your theory is worth looking into, because it's only a small percentage of the potentially effected users, I'd think it far more likely to be something done to or with that brand/size of tire than the tire itself... like maybe the pressure?? :dontknow: And that thought is increased because so far, only one of those with these tires/that ongoing issue has replied to say they are using a pressure in the calculated optimal range for that tire when used under 'normal' loads, temps, & speeds... plus, I'm only working off anecdotal info/data! :sour: It'd be so nice to visit and actually physically investigate & test all if this, but them's the breaks, I guess! :banghead:
Poppie65
Active member
So this afternoon I reduced the rear tire air pressure from 21 to 18 PSI, then rode over to pick up my wife at her job. I rode solo on a 70 MPH highway and was very pleased to find that the vibration wasn't there. I slowed down, sped up, rolling through the rpm range and didn't feel a thing. Wow!!
We rode 2-up on local roads for a while then jumped on another 70 MPH road and while purposely slowing down and speeding up I was able to duplicate the vibration to a degree, but it was noticeably
& significantly reduced in intensity. I'm very impressed Peter!
I want to put more miles on it to isolate the vibration with the lower air pressure, but it's gonna be a couple of weeks. Work travel will prevent anymore riding until early October.
I'm very encouraged so far. Maybe a slight belt tension reduction will eliminate the remaining vibration.
Something else that I noticed going through curves, it felt like the rear tire didn't track as well with the lowered pressure. Kind of like the side walls had more flex and it wasn't a very comfortable feeling.
We rode 2-up on local roads for a while then jumped on another 70 MPH road and while purposely slowing down and speeding up I was able to duplicate the vibration to a degree, but it was noticeably
& significantly reduced in intensity. I'm very impressed Peter!
I want to put more miles on it to isolate the vibration with the lower air pressure, but it's gonna be a couple of weeks. Work travel will prevent anymore riding until early October.
I'm very encouraged so far. Maybe a slight belt tension reduction will eliminate the remaining vibration.
Something else that I noticed going through curves, it felt like the rear tire didn't track as well with the lowered pressure. Kind of like the side walls had more flex and it wasn't a very comfortable feeling.
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This is something that a few riders/drivers comment upon, and I have to say that very much the same concerns were raised way back when radial tires first came out and people felt the 'soft & spongy ride with a bit of a wallow' vs the much firmer & seemingly 'more direct' ride & handling that cross-ply tires imparted! But just like this was tested back then, and has now been tested again on our Spyders on the track and braking test beds by some, as well as on the road by many, many people now over what must literally be collectively, millions of miles - radial tires like those you are running DO 'feel different' when run at appropriate pressures for the load imposed upon them vs when they are over-inflated - they DO feel as if they have more flex than a tire pumped up too hard/high, only that is because by design, they do flex in the sidewalls more in order to keep more tread on the road for more of the time!! But by doing that, they also provide increased traction, better performance, and greater roadholding ability too - especially in the wet &/or when they start to get pushed hard!!
hyea:The 'wasn't a very comfortable feeling' you felt is most likely because you've become used to running them harder/at a higher pressure than is strictly needed &/or ideal, and so you now think/feel that 'feel' equates to 'better'... only it doesn't! :lecturef_smilie:
Give yourself some miles and saddle time to get used to it - take it easy at first tho! It's very likely taken you quite some time to 'get used' to feeling that the ride & handling you got with your tire a little over-inflated was 'right', so it'll probably take at least a little while for you to get used to the different feeling you're now getting with running the tire at a more appropriate pressure; but for most, the more comfortable ride, the better grip, handling, & traction (especially in the wet/when being pushed hard - but work up to the latter!
) tends to make the learning curve somewhat shorter and the overall 'feeling better/safer & more comfortable with the changes' come along much quicker. :thumbup:Glad you found it reduced the vibration too tho. That does add some weight to my thoughts that the tire pressure was at least contributing to the vibrations you were experiencing. :cheers:
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Dasmoetorhead
Active member
Glad you got it figured out Ron. My tire psi in the rear is already at 18 so I don't think that'll work for me. I'll have to experiment when we get back home in Nov. Until then all I can do is read about Spyders.
We're parked in Salt Lake City, and heading to Winnamucca NV.
Enjoy that vibration free Spyder. Cheers!
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troop
Well-known member
I've also been running 20# on the Altimax. I'll give 18# a try, especially since I'm a 100% solo rider.
Poppie65
Active member
I'm very interested to hear how it works for you. I couldn't get the vibration to reappear at all while I was solo. My ride was only about 5 miles, but it gives me cause to be optimistic.
This is something that a few riders/drivers comment upon, and I have to say that very much the same concerns were raised way back when radial tires first came out and people felt the 'soft & spongy ride with a bit of a wallow' vs the much firmer & seemingly 'more direct' ride & handling that cross-ply tires imparted! But just like this was tested back then, and has now been tested again on our Spyders on the track and braking test beds by some, as well as on the road by many, many people now over what must literally be collectively, millions of miles - radial tires like those you are running DO 'feel different' when run at appropriate pressures for the load imposed upon them vs when they are over-inflated - they DO feel as if they have more flex than a tire pumped up too hard/high, only that is because by design, they do flex in the sidewalls more in order to keep more tread on the road for more of the time!! But by doing that, they also provide increased traction, better performance, and greater roadholding ability too - especially in the wet &/or when they start to get pushed hard!!
The 'wasn't a very comfortable feeling' you felt is most likely because you've become used to running them harder/at a higher pressure than is strictly needed &/or ideal, and so you now think/feel that 'feel' equates to 'better'... only it doesn't! :lecturef_smilie:
Give yourself some miles and saddle time to get used to it - take it easy at first tho! It's very likely taken you quite some time to 'get used' to feeling that the ride & handling you got with your tire a little over-inflated was 'right', so it'll probably take at least a little while for you to get used to the different feeling you're now getting with running the tire at a more appropriate pressure; but for most, the more comfortable ride, the better grip, handling, & traction (especially in the wet/when being pushed hard - but work up to the latter!
Glad you found it reduced the vibration too tho. That does add some weight to my thoughts that the tire pressure was at least contributing to the vibrations you were experiencing. :cheers:
This is really a good reply. I was going through the exact same feelings as Poppie65 and wondering why I be bike felt softer in the back after switching to Altimax and running at 20 PSI. I do like the feeling MUCH better but worried just a bit that maybe I was underinflated. Your explanation really makes sense and brings a smile to my face as I ride.
troop
Well-known member
Took my first decent ride last night after dropping my rear tire pressure down to 18.5# No belt vibration felt anywhere. Hmmmm
Dasmoetorhead
Active member
I'm sure ya'll are quite tired of this vibration thread, but here's my latest observation.
I've been traveling for the past 6+ weeks in our motorhome, and had plenty of time to read, and think about my next plan of attack on my vibration problem.
Yesterday (a day after our return home) I put the cat delete pipe back on just for giggles, and also checked tire air pressure. I found all tires a bit low on air.
I have been intrigued about the different tire psi recommendations on this forum, and the positive and maybe negative results from varying pressures.
So I decided to change it up a bit. I've been running 18 psi on all tires as my starting point. Ever since I put all new tires on, I've been running those psi. I have had a terrible vibration ever since.
I decided to try 20 psi in front and 22 psi in the rear. What the heck. It's easy enough to do.
Went for a short ride and I experienced Zero belt vibration. Particularly where in the speed, load, and rpm's where I had experienced this vibration, and it's gone.
My belt tension is at 220 on the Krikit gauge.
Now in the past when I run with the Baldwin Iron Works cat delete pipe, I immediately notice less engine vibration. I can usually feel it in the grips. The delete pipe reduces back pressure which is what I believe to be the cause of less engine vibration. IDK.
So I hope this has permanently addressed this situation.
I'm not sure why this adjustment worked, but it did.
I'm a happy camper now.
Now on the issue of the cat delete pipe, I kinda like the exhaust note, but even with the stock (secondary muffler/can) it's pretty loud when you roll on the throttle. It has a super good note at idle. Are the F3S Cans louder than the other Spyder models? IDK, but to me it's almost too loud. In the past, when running the delete pipe I've noticed loss of low-end torque, gas smell at idle, smother shifting, a little better fuel mileage, and the bike seems to go from 60 mph to 100 mph quicker. I've never been beyond that so I don't know how fast it will actually go. I know from what I've read on here that the top speed is limited to a known factor which I have no idea what that is.
I wanted a little better exhaust sound, and I definitely got it. Seriously though, I believe the stock exhaust sounds good to me also; but being a gearhead and tinkerer, I have to mess with things. It's just in my nature. Anyway, I'm very pleased with my findings, and I'm going to run the F3S in this configuration and give it a good long-term test.
Thanks for all the tire pressure advice from the experts on here.
I've been traveling for the past 6+ weeks in our motorhome, and had plenty of time to read, and think about my next plan of attack on my vibration problem.
Yesterday (a day after our return home) I put the cat delete pipe back on just for giggles, and also checked tire air pressure. I found all tires a bit low on air.
I have been intrigued about the different tire psi recommendations on this forum, and the positive and maybe negative results from varying pressures.
So I decided to change it up a bit. I've been running 18 psi on all tires as my starting point. Ever since I put all new tires on, I've been running those psi. I have had a terrible vibration ever since.
I decided to try 20 psi in front and 22 psi in the rear. What the heck. It's easy enough to do.
Went for a short ride and I experienced Zero belt vibration. Particularly where in the speed, load, and rpm's where I had experienced this vibration, and it's gone.
My belt tension is at 220 on the Krikit gauge.
Now in the past when I run with the Baldwin Iron Works cat delete pipe, I immediately notice less engine vibration. I can usually feel it in the grips. The delete pipe reduces back pressure which is what I believe to be the cause of less engine vibration. IDK.
So I hope this has permanently addressed this situation.
I'm not sure why this adjustment worked, but it did.
I'm a happy camper now.
Now on the issue of the cat delete pipe, I kinda like the exhaust note, but even with the stock (secondary muffler/can) it's pretty loud when you roll on the throttle. It has a super good note at idle. Are the F3S Cans louder than the other Spyder models? IDK, but to me it's almost too loud. In the past, when running the delete pipe I've noticed loss of low-end torque, gas smell at idle, smother shifting, a little better fuel mileage, and the bike seems to go from 60 mph to 100 mph quicker. I've never been beyond that so I don't know how fast it will actually go. I know from what I've read on here that the top speed is limited to a known factor which I have no idea what that is.
I wanted a little better exhaust sound, and I definitely got it. Seriously though, I believe the stock exhaust sounds good to me also; but being a gearhead and tinkerer, I have to mess with things. It's just in my nature. Anyway, I'm very pleased with my findings, and I'm going to run the F3S in this configuration and give it a good long-term test.
Thanks for all the tire pressure advice from the experts on here.
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