180 on an SV

[yorkie_chris]

Ever heard of someone putting ZX6R B1 wheel on back? Is 5.5" and looks similar.

Anyone here got one to take some preliminary measurements?

Originally Posted by yorkie_chris

Ever heard of someone putting ZX6R B1 wheel on back? Is 5.5" and looks similar.

Anyone here got one to take some preliminary measurements?

Havent heard of that one. The CBR one fitted so well barring the spacer it looked like it was made for the SV! LOL. Very cheap too off ebay. Just make sure if you get on that its the post 95 model one with the 5 inch rim as the pre 95 wheels look the same but are 4.5 inch on the rim and will flatten the profile of the 180.

[fastdruid]

Biggest advantage IMO is that 120/180 'pairs' seem to be in the sales all the time, hardly ever see any 120/160 pairs for sale. :-/

Doubt it would make much difference to turn in, while it mght slightly, the turn-in speed is more dictated by the geometry[1], what it does do is reduce the speed you can carry a certain speed at. Or to put it another way, if you were to take a corner at 40mph on two identical bikes, one with a 160 rear and one with a 180 rear you'd need to lean more on the bike with a 180 rear. As to the actual amount and if it makes a difference in reality I don't know.

Druid

[1] The SV is a lardy bus compared to for example an NC35 which has a 10cm shorter wheelbase, even when the NC35 is wearing the same size tyres (std NC35 is 150 rear but a 160 fits).

[yorkie_chris]

SV has cruiser geometry as stock. Shorter forks and a 350mm shock soon sort that.

I don't believe you about the lean angle. Surely F = mv^2 / r and the F is a sin of the weight at some angle to the vertical.

Originally Posted by Aquila

I thought this was a speed thread!!!

Me too lol. 180mph!!! Who's done it?

[fastdruid]

Originally Posted by yorkie_chris

SV has cruiser geometry as stock. Shorter forks and a 350mm shock soon sort that.

It's still 10cm longer wheelbase and you can't do much about that! My SV is ~1 inch down at the front and ~1 up at the back, to the point where it is twitchy but not excessively so, it handles fantastically and it still isn't a patch on how the NC handles.

I don't believe you about the lean angle. Surely F = mv^2 / r and the F is a sin of the weight at some angle to the vertical.

Lol, its more to do with the difference between your real angle and the contact patch, wider tyres move the contact patch away from the centre line of the bike.

See http://books.google.co.uk/books?id=8...20book&f=false

Page 2-17 and 2-18, which says

figure 2.5 shows how the contact patch moves away from the centre plane of the wheel or the steering axis as the bike is banked. A greater angle of lean is necessary to maintain balance, and this may require a slightly higher centre of gravity to restore cornering clearance. It may be necessary to add around 5 degrees more to the lean angle when cornering at 1g to compensate for the width of modern tyres.

Druid

just dropped mine 5mm at the front at jacked the back up buy 38mm not sure how the 5mm at the front will make a diff but the back made a huge difference

at some point i would like to put a 180 on the rear but not at the moment

[yorkie_chris]

Ok so I missed that part entirely

A short wheelbase isn't the be-all and end-all of good handling though. You could probably get some good improvement by getting rid of the 'busa forks and fitting some revalved GSXR6/750 ones.

What shock have you got? Is it meant for SV or is it a SRAD one?

[fastdruid]

I've got some GSXR6 forks to go on[1], The shock is a proper SV Ohlins one.

But that won't appreciably change the speed at which you can turn in[2]. The NC is insanely quick to turn in. While wheelbase is not the be-all and end all it makes a *huge* difference as to how quickly you can turn in.

I'm once again going to refer back to the book I referred to before, page 3-16 now;
http://books.google.co.uk/books?id=8...20book&f=false

Wheelbase


The distance between the wheel centres has several effects but, in general, the longer the wheelbase the greater the directional stability and the greater the effort needed to negotiate bends. There are three main reasons for this.

1) Required steering angle
Figure 3.20 shows how, for a given bend, a long-wheelbase machine needs the front wheel to be turned further into the bend. Consequently more effort is required for cornering; also, a given deflection of the front wheel (say, from bumps) will have less effect on its directional stability.

2) Rear-wheel angle
It is also clear from figure 3.21 that, for a given sideways deflection, the angle of the rear wheel to the direction of travel is smaller with a longer wheelbase, this improving directional stability

3) Inertia effects
The wheelbase has an effect on load transfer under braking and acceleration; for a given centre-of-gravity height, the longer the wheelbase the smaller the load transfer. In addition, the moments of inertia in the pitch and yaw planes are increased, which makes a long-wheelbase machine more sluggish and stable.

Druid

[1] I just need a GSXR6/750K6-K8 front wheel & discs.
[2] Except maybe at high speed, the GSXR6/750 wheel is lighter than the TL and runs smaller lighter brake discs.

[yorkie_chris]

But speed of turning is not the be all and end all of handling, everything is a compromise. I bet the SV can put its power down without wheeli-ing more easily for example.

Was that ohlins fresh out of box or has someone revalved it?