View Full Version : Rear tyre too wide for SV?
The SV rear wheel is quite heavy.
Do you think switching to a lighter/thinner 140 rim and tyre is a good idea.
The steering would benefit as well.
Sometimes I think that the SV was given a 160 rear just to look good.
What's your opinion on this guys?
p.s. I'd like my SV to be a 140kg machine
I reckon the 160's quite well suited to the bike, but it's an interesting thought as most people go the other way.... 150 section tyre was standard on the Bandit 600 (early ones like I had anyway) and that was just fine. I doubt you'd get any weight saving at all going to that wheel and tyre though. The weight saving will have to come from the wheel itself, got any thoughts on a donor bike?
The "correct" way to go to save weight is to get a nice Dymag wheel on the rear.... But that's not a cheap option....
I'd reckon most of the bikes that take a 140 rear are pretty old now as it hasn't been sexy for a long time. The donor wheels might, therefore be heavier than the one on the SV due to improvements in manufacturing.....
But then, if I'm honest I know jack-all about this sort of thing....
Jambo
chazzyb
17-01-08, 01:03 PM
The SV rear wheel is quite heavy.
Blimey! Everytime my SV's rear wheel is out I think how light it is - compared to spoked wheels as all my other bikes have.
Have you ever had to remove the rear chazzyb? I'm telling you if you had a lighter wheel there a lot of weight saving could be done. Some guys are telling me that the stock forks are quite heavy as well. They're saying the Gixxer forks are half the weight and these are upsidedowners. Quite interesting when I thought that the upside down items should be heavier just by looking at them. The dymag wheel change is an option I suppose but not many people are willing to pay that much. If you look atb grey import 400cc inline 4's they mostly run on 140's and are quite capable of having a good contact patch and all that as most can keep up with theSV twin no prob. That's why I'm thinking the 140 rear section could be a good cheap option for a lighter bike. And if you ever had the chance to ride a light bike you'd know of the benefits that can be got.
northwind
17-01-08, 10:17 PM
The rear wheel's pretty heavy, definately... I'm still messing about with a CBR900 fitment Dymag rear, it saves, oh, lots. Don't know exactly how much tbh. Is there good availability for such relatively narrow tyres? Or wheels for that matter?
Dymags should save 1-1.5kg for each wheel. However the tyres themselves are a huge source of weight. The difference between different brands of tyre can be up to 1kg per wheel! That's the same benefit as a set of dymags just by choosing different tyres. Worth looking into if you can find a friendly tyre shop to weigh a few sets for you.
That's a good question Northwind. To be honest the idea of a narrower tyre germinated in the dark corners of me mind when I read reports from supermono racers of advantages in having narrower tyres for a given amount of bhp. It seems like wider tyres on production motorcycles are more of a fasion statement in most cases. In the case of the SV with 'only' 70-80bhp; which is quite enough power honestly for most of us, if used fully and reliably; a 150 section would actually have been a better fitment. These 150 section are used and available for supermono racers. Quite a lot can be learned from these light machines. I'm starting to see the sense in their thinking. Google supermono out and see what I mean.
A good exercise, for anyone with the means of having a breaker friend, is to check out the weight of varied 140/150 section rims and see if there is a real weight difference from which we may benefit. If there's a substancial amount maybe we could pursue the idea further. Apart from having gixxer forks and a light exhaust to lighten the SV I can't think of anything other that can reduce its weight by a noticeable amount. The rear aluminium subframe difference to stock isn't that much is it?
"Dymags should save 1-1.5kg for each wheel. However the tyres themselves are a huge source of weight. The difference between different brands of tyre can be up to 1kg per wheel!"
Quite right, so imagine having a narrower tyre, less material, less weight.
The subframe can make quite a difference depending on how minimalist you go. If all your after is a seat perch then yes it can. If your keeping the road trim then the frame has to be much larger and thus the savings will be less.
northwind
18-01-08, 06:37 PM
Dymags should save 1-1.5kg for each wheel.
It's going to be a bit more than that I reckon, just by dead reckoning... I think it was 1.4 from the front going from GSXR wheel to Dymag, but the GSXR wheel in turn is lighter than the SV. Unfortunately I didn't keep very good records :rolleyes: The SV rear is like an anchor though. If I get out to the garage this weekend I'll do some weighing.
Thanks Northwind the data would be nice. Did you ever find a domestic way to weigh the bike? Nice wheels those Dymags by the way! Stuff of dreams.
yorkie_chris
19-01-08, 05:06 PM
A weighing scale and a block of wood the same height, weigh the front then weigh the rear. Should be pretty accurate.
northwind
19-01-08, 05:14 PM
Yep, exactly. Bathroom scales. Though I did explode a set once, they can deal with the weight but not when it's all on one edge.
Stuff of dreams? Nah. Stuff of Ebay :D The set's cost me less than a pair of fairing lowers, and undertray and a single seat cowl would.
TheStudent
29-04-08, 03:50 PM
Would a GSXR rear tyre not have handling benefits being wider? Is it an easy swap for an SV?
Tom
yorkie_chris
29-04-08, 03:52 PM
Not really, looks better that's about it.
TheStudent
29-04-08, 03:53 PM
Not really, looks better that's about it.
Why so much wider on say a GSXR600 then?
yorkie_chris
29-04-08, 03:56 PM
How much power does the SV make?
TheStudent
29-04-08, 03:59 PM
How much power does the SV make?
SV 70bhp vs. 120bhp GSXR, iirc!? So why wider?
Dangerous Dave
29-04-08, 04:00 PM
How much power does the SV make?
Depends on the SV!
Nah... a 180 tyre on a SV is for looks only, stick with a standard 160. A modern 600 could run on a 160 too easily, its not the power that is the limiting factor its the tyres for racing mainly!
Blue_SV650S
29-04-08, 07:51 PM
I think you might struggle to get decent rubber in a 140 fitment?!!? :scratch:
May I ask why you are trying to reduce the weight of your bike?? Just an idle project/aim or is it to some end?!?! :confused:
northwind
29-04-08, 08:58 PM
Was that for me or for Zunkus? With me it's just a hobby, though the light front wheel is very nice for cack-handed last-minute course changes :D I'm sure if I was faster I'd feel more benefits, but I'm not. Also, it helps push the bike uphill, mine in its current trim is about 170 kilos fully wet compared to, what, 185, 190 standard? So that's a well noticable difference.
Blue_SV650S
29-04-08, 09:01 PM
Was that for me or for Zunkus? With me it's just a hobby, though the light front wheel is very nice for cack-handed last-minute course changes :D I'm sure if I was faster I'd feel more benefits, but I'm not. Also, it helps push the bike uphill, mine in its current trim is about 170 kilos fully wet compared to, what, 185, 190 standard? So that's a well noticable difference.
My original post was directed at Zunkus; I know you simply like to fiddle!! 8)
Easiest method for weighing tires, rims, cans, etc (just about anything you can hold comfortably):
Pick up the part, stand on the scale, write down the weight.
lay down the part, stand back on the scale, write down your weight.
Subtract your weight from the combined weight, it will give a pretty accurate measurement. Also puts your bathroom scale in the range where it is most accurate.
If you are really heavy, say close to the 140kg top range of most bathroom scales, just get a skinny friend to do the holding. I have one Harley friend who has to do this.
northwind
29-04-08, 11:07 PM
I tried that, didn't work to any reasonable degree of accuracy, so I got a couple of small fishing scales instead.
Hahahaha:notworthy:
We must have better bathroom scales over here, (mine's DIGITAL:rolleyes:) and you must have better fishing scales, ours are outrageously optomistic, and seldom repeatable!
Best place in the US ( at least in a small town), if you really want more than just a ratio, is the postal service. If you have a friend there, you can get an accurate reading, at least down to the ounce.
northwind
30-04-08, 12:51 PM
Mine's digital, but using that method still said all my wheels weighed exactly 6.2 kilos :D I've checked the fishing scales against known quantities (I used myself as a calibration tool on my big scale, got weighed at the hospital then went home and weighed myself :D)
yorkie_chris
30-04-08, 01:05 PM
and you must have better fishing scales, ours are outrageously optomistic, and seldom repeatable!
Isn't that just the fisherman saying "it were thiiiiis big!"
http://www.cartoonstock.com/newscartoons/cartoonists/pju/lowres/pjun439l.jpg
LEXINGTONONE
30-04-08, 01:45 PM
I know it,s a little off topic (but isn,t everyone else anyway!) but as for the why try and lighten the sv, although it,s not the heaviest (especially in feel) bike in the world, lightening any bike is about the best thing you can do to it, it helps in every department, on that subject one thing (and this is nearly back on topic!) that I have given some thought to is that huge rear disc and caliper, why so enormous ! anyone ever fitted a smaller disc and caliper (something off a moped or the like would do as we dont use the back much do we ?) also I am surprised to hear the comment that gixer forks are lighter than the sv ones, I have been told by more than one reasonably well informed expert (?) that the gixer ones are quite a bit heavier as are most usd forks in comparison with rwu,s,
yorkie_chris
30-04-08, 01:51 PM
You don't have to use USD's...
SRAD600 and k1-k3 600 are RWU.
plowsie
30-04-08, 01:54 PM
180/55 on the bike looks cool and is very fun to try and relieve the rear of chicken strips :) I never had any problems with handling IMHO. 140 would deffo turn a lot quicker, remember though, lean angle may be affected.
May I ask why you are trying to reduce the weight of your bike?? Just an idle project/aim or is it to some end?!?! :confused:
Sorry for not participating lately on this thread but been having some monitor problems at home and sort of had to sneak in here during work (quick looksee if boss is around, no ok).
I have a very light Supermoto for daily commute, it's around 130kg fully loaded (without me of course, you'll have to add an extra 75-80kg then).
I've noticed how much easier to live with it is on a lighter bike and how much more fun it can be. I'd just love to lighten it just for that cause. I'm not into racing, though I do play Rossi now and then come Sunday or after watching a race, but mostly I'm just another guy who likes to thinker, Hi Northwind! :notworthy:)
The smaller rear disc brake is a good idea. For one thing that stock big brake is dangerous in the wet if you're a bit of a stomper with your back brake and second as someone here said, we don't really use the rear that much do we?
I honestly think that for 70ish bhp the rear tire on the SV is simply unnecessary but nice to look at being a 160 and could have benefited (other than lack of supply) by being a 140. The rim would have been thinner and lighter and so would the tire. I'm into marketing and think that some things are done mostly for marketing or for using stock parts bins and not always because the bike/rider benefits from it. I think the rear tire is a case in point. (just to prove this, a 4 cylinder 600 would benefit from having more midrange torque but the manufacturers keep competing in the top bhp figures; why because that shows up on the magazine specs page and when Joe Public's deciding that's what he looks at).
northwind
30-04-08, 05:58 PM
I know it,s a little off topic (but isn,t everyone else anyway!) but as for the why try and lighten the sv, although it,s not the heaviest (especially in feel) bike in the world, lightening any bike is about the best thing you can do to it, it helps in every department, on that subject one thing (and this is nearly back on topic!) that I have given some thought to is that huge rear disc and caliper, why so enormous ! anyone ever fitted a smaller disc and caliper (something off a moped or the like would do as we dont use the back much do we ?) also I am surprised to hear the comment that gixer forks are lighter than the sv ones, I have been told by more than one reasonably well informed expert (?) that the gixer ones are quite a bit heavier as are most usd forks in comparison with rwu,s,
I think the actual forks are heavier, as are the discs, but the yokes and other parts are lighter so the total weight is less. I'm swapping rear wheels and it needs a different brake caliper hanger anyway, so I'll be fitting something different then... Got a couple of options. Most rear calipers are pretty weighty though, strange that considering how much effort they put into saving weight elsewhere. But then reducing unsprung rear weight is less dramatic than front because of the larger total unsprung parts.
LEXINGTONONE
30-04-08, 07:19 PM
I was wondering more about what disc could be used, dont think finding an alternative smaller caliper and mounting it would be difficult but it would be a thankless task trying to find a smaller disc to bolt on standard wheel (ok for those of us with fancy lighter non standard wheels !) I agree about the unsprung weight not being as big an issue on rear but every little bit helps ?
Sorry for not participating lately on this thread but been having some monitor problems at home and sort of had to sneak in here during work (quick looksee if boss is around, no ok).
I have a very light Supermoto for daily commute, it's around 130kg fully loaded (without me of course, you'll have to add an extra 75-80kg then).
I've noticed how much easier to live with it is on a lighter bike and how much more fun it can be. I'd just love to lighten it just for that cause.
but mostly I'm just another guy who likes to thinker, Hi Northwind! :notworthy:)
I honestly think that for 70ish bhp the rear tire on the SV is simply unnecessary but nice to look at being a 160 and could have benefited (other than lack of supply) by being a 140. The rim would have been thinner and lighter and so would the tire.
I'm into marketing and think that some things are done mostly for marketing or for using stock parts bins and not always because the bike/rider benefits from it. I think the rear tire is a case in point. (just to prove this, a 4 cylinder 600 would benefit from having more midrange torque but the manufacturers keep competing in the top bhp figures; why because that shows up on the magazine specs page and when Joe Public's deciding that's what he looks at).
Like the idea of using a light weight supermotard for commuting, would suit me if shortened to normal street bike height. I'm only 60.5kg, I find the SV just a tad heavy for the commute.
I did have some old bike mags some time ago and remember one had an article on tyre sizes.
It said that rear tires sizes went big when the power of the GP bikes had increased to the point that the skinny rear tires could no longer cope with the power. It also showed a photo of the late B Sheenes's bike with an almost shredded rear. So the SV should be OK with a smaller size.
It does appear as though everything is designed to look good 'the trend', I wonder what a bike would look like if it was strictly functional, including fully enclosed chain, full length mudguards for the moist weather we have in the UK.
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