up size anakee's

[simon.110]

hi all.

2 months in on my purchase of a A1 09 GSA from wollaston.. my third boxer.. and loving it.
going thru the usual mod stuff.. silencer/headers (full system off ebay for £60)!!!!! booked in at hilltops for the remap next month

although the bike came with a new set of tourances. i was wondering if anybody has yet fitted the larger LC sized anakee's to a hexhead. 120 on the front and 170 on the rear. they look a bit more meaty!! than the 110/150 arrangement that is standard..
are the rims similar sizes?? are they better? or do they upset the bike.

on a seperate issue i'm 5'8 and spend the whole time looking thru the bend of the turn up on the screen! any answers.. need to maintain the LARGE look so dont wont a "girls" screen
regards
simon

 

[mikeyboy]

they handle perfectly well on the standard size tyres why fuck it up

 

[Bendy toy]

Agree about the tyres. The bike won't benefit from wider rubber and may well be spoiled. I have Tourances showing zero chicken strips. The limit is ground clearance not tyres.

I am a similar height my screen problem (motor way buffeting was improved with tobinators to lift the screen front so it leans back further. It was solved with a Givi Airflow 330 screen (and the tobs).

 

[Nick V]

they handle perfectly well on the standard size tyres why fuck it up

To each their own... on my previous '09 GSA, I specified standard-sized spoked wheels, and used regulation-issue 150/70 rear and 110/80 front Anakee 2s. Enough grip and handling to show up a lot of badly-ridden sports bikes - especially around Long Tom Pass.

On the current '09 GSA, I'm using a K1200S rear wheel with a 190/55 Pirelli Diablo Supercorsa. Soon, it will be joined by an R1200S front wheel wearing 320mm discs and a 120/70 Supercorsa.

With it's current setup, the bike is easy, docile, predictable and flickable. It just wants to please, and refuses to tank-slap even if I poke it quite hard.

(The Supercorsa and Supercorsa Pro are track-day rubber. I get them from a guy who runs a Ducati 1098S at Kyalami on the weekends, at R200 to R250 a pop. )

 

[Bendy toy]

17" wheels at both ends will allow typical sports bike tyre pairs to be used. Smaller front wheel will steer quicker and you get a wide choice of rubber.

The issues could be ABS/TCS getting confused by different wheel speeds and reduced ground clearance.

 

[Packer]

As said above, standard original Tourances give enough grip on good surfaces to ride to the sidewall of the front tyre and you run out of ground clearance before adhesion. What is the point of reducing the ground clearance and therefor inhibiting cornering ability?

 

[Nick V]

17" wheels at both ends will allow typical sports bike tyre pairs to be used. Smaller front wheel will steer quicker and you get a wide choice of rubber.

The issues could be ABS/TCS getting confused by different wheel speeds and reduced ground clearance.

I had this issue on the GSA and solved it.

As it turned out, the ASC was being confused not by a different rolling circumference, but by a lower final drive ratio (which made it think the rear wheel was turning faster than 'normal' and therefore, that there was wheelspin).
Going up from a 180/55-17 to a 190/55-17 sorted it.

Changing tyre sizes has had no effect on the ABS.
That conclusion is backed up by another contact of mine here in SA, who has already done the 17" front conversion on his '09 GSA. He has no ABS or ASC issues running a 180/55 on the rear, but then he's using a longer final-drive ratio than I am.

For interests' sake, he's using wheels from an R1200RT (5.5in rear), standard (305mm diameter) R1200GS front brake discs (so as not to have to alter the caliper position) and an F800ST front mudguard.

As said above, standard original Tourances give enough grip on good surfaces to ride to the sidewall of the front tyre and you run out of ground clearance before adhesion. What is the point of reducing the ground clearance and therefor inhibiting cornering ability?

There are a number of possible ways of getting around this:

1. Experimenting with the static ride height.
2. Experimenting with different preload settings (on an ESA-equipped bike).
3. Using a taller-profile rear tyre (bearing in mind that this will also effectively lengthen your final-drive ratio).

But to answer your question: as was pointed out, a 17" front enables you to use much grippier (i.e. sports bike) rubber. That configuration gives you:

1. A much wider choice of rubber, and access to softer compounds.
2. The above leads to added grip, giving you a wider safety margin.
3. Further enhancing your grip is the wider profile of a 120/70 (as opposed to 110/80) tyre, which puts more rubber on the road.
4. A wheel with a rolling diameter of two inches less will have less rolling inertia, contributing to faster steering and changes of direction. It will also lower the front end of the bike, steepening the head angle and further contributing to quicker steering.

There are two possible disadvantages:

1. Lowering the front end by an effective one inch will have a negative effect on cornering ground clearance. (By how much, the deponent knoweth not.)
2. Lowering the front end (and thereby steepening the head angle) MAY give the bike a propensity to tank-slap, or increase said propensity if it's already there. (The possibility of grafting in an R1200S bottom triple clamp and steering damper might be of interest.)

 

[Bendy toy]

I would avoid fitting a steering damper. They help to mask a wiggle and might avoid a tank slapper starting. But when a real one does kick off, it will hit with greater amplitude. A damper can mask the wiggle warning of a developing slapper.

For grip I have no problem with the standard size wheels. I would like to try some dual compound road touring tyres on both ends but they only exist in 17" so a wheel conversion would be needed.

 

[Nick V]

For grip I have no problem with the standard size wheels. I would like to try some dual compound road touring tyres on both ends but they only exist in 17" so a wheel conversion would be needed.

Maybe you wouldn't have to...
My memory is a bit hazy on this - but aren't Michelin Pilot Road 3s and Road 3 Trails available in dual-compound (2CT)?
They're available in standard GS/GSA sizes.

 

[Bendy toy]

Thanks, I'll have a look when the current set are due.

 

[babble]

Just go all the way

they handle perfectly well on the standard size tyres why fuck it up

+1

If I needed stickier tyres, I think I'd need a faster GS to go with them, with sharper handling, and better brakes..... maybe if i bought a Daytona 675R and attached it to the sticker tyres I'd have the perfect trackday GS?

 

[Nick V]

+1

If I needed stickier tyres, I think I'd need a faster GS to go with them, with sharper handling, and better brakes..... maybe if i bought a Daytona 675R and attached it to the sticker tyres I'd have the perfect trackday GS?

It's not quite that simple.

A GS won't break your back, destroy your wrists or deafen you with wind-blast over a 1 600 Km road trip.

People tend to forget the raison d' etre of sports bikes. They are based on machinery you see on TV, being ridden by twenty-something supermen with a body-fat ratio of 2% and a max height of 5"6, being thrashed like hell for relatively short periods of time.

You could try to undertake a 1 600 Km road trip, two-up with luggage, on a Daytona 675R. But the result will not be desirable or particularly efficient.
Cue frayed nerves and recriminations.

On the other hand, even a bog-standard 100 BHP first-generation GS will, given two riders of equal skill, be mounting a deadly serious challenge to a Daytona 675R around the average mountain pass - especially when the road surface becomes inconsistent and difficult to read, and the roads degenerate into hairpin bends, as so often happens on the average mountain pass.

In situations like that, a bike sporting compliant, long-travel suspension and with a big-capacity engine packing substantial low- and mid-range power is the one to go for.
More importantly, where your 675R rider is in his element at 100% throttle on smooth roads for an hour at most before the pain forces him to stop, your R1200GS rider is in HIS element at 75% to 100% throttle on almost any road surface, for as long as there is fuel in the tank.

This is why the GSs and GSAs have the potential to work so well as supermotos. Honestly, a GSA supermoto will never be a KTM Duke. But you will never cruise for 100 Km at a steady 160 Km/h on a Duke, either.

The secret is overall versatility.
This exercise is all about taking the GS's strengths and focussing them in a slightly more specialized direction.

 

[Nick V]

It occurs to me that I could have summed up that previous post by pointing out that the Daytona was built for sanitized, velvet-smooth racetracks. The GS was built for real-world riders on real-world roads.

While the Daytona only has about 40% of the GS's every-day, real-world versatility, usability and comfort, it's fair to say that the GS has at least 80% of the Daytona's speed and manoeuverability.
Actually, in any situation where the road is less-than-ideal, that ratio goes over 100%.
Sports bikes with ultra-short wheelbases and firm, short-travel suspension are great for smooth-tarmac racing. But fast riding on public roads requires the kind of constant improvisation that you don't need on a track. Trying to keep up with a well-ridden GS means the poor Daytona rider, his fillings being rattled out of his head, will be riding at a level of concentration and commitment that leaves nothing in reserve for the next tightening-radius bend, pot hole or stray cow...

If I had unlimited funds, and I didn't need my bikes to be all-singing, all-dancing, I would have a Daytona 675R as a Saturday-afternoon track-day toy. But in my opinion, anyone who tries to ride one all year round on real-world roads is kidding themselves. If we're at all honest with ourselves, that's not what it's built for.

 

[Bendy toy]

My 08 GSA on standard Metzeler tyres with ESA front shock that's done 42K and back that's done 15K is by far the best handling bike I have used on the road. Its not particularly fussed about crumbling road surfaces, its amazingly stable yet will handle quickly when its asked to. It can hit pot holes leaned over and it just rocks a bit. There is never any sign of squirming or wriggling that my other bikes did.

I use all of the tyres and maintain much higher cross country speeds that on any other bike. The chicken strips are non existent but frankly I could not use any more rubber even if the bike had it because I'm already moving at silly speeds. My head has still not recalibrated from the old days of bikes that felt fast while going slow.

The bike is limited by the roads not by its ability. The only thing lacking is a radar to spot other vehicles/hazards around a bend so I could keep it pinned for longer.

This is why I'm not bothered about fitting wider rubber. It's simply not needed and it might even spoil a good overall setup.

 

[Nick V]

This is why I'm not bothered about fitting wider rubber. It's simply not needed and it might even spoil a good overall setup.

You're right.
Something else people tend to forget is that while a wider rear will put more rubber on the road, it's the rear tyre's overall profile that has the most influence on how the bike will handle.

My GSA felt good when I got it with the 180/55 rear. But going to a 190/55, it felt decidedly more agile when doing aggressive 'flicks'. Going back temporarily to the 180/55 for comparison, it actually felt wooden.

For the doubters: take a look at the longitudinal profile of a 180/55-17 tyre versus a 190/55-17 sometime. You will see that the 190's profile is noticeably 'sharper'. It's this profile that gives the bike such amazing reactions, by letting it 'tip in' faster, then take advantage of an increasing surface area as you lean it further.

But all that is really a 'nice-to-have'. My old GSA, on standard-sized Anakee 2s, handled brilliantly and had more than enough grip for almost any fast riding scenario.

 

[Bendy toy]

As Nick says, tyre profiles are not just about the amount of rubber on the road. Within limits, wider tyres give a larger footprint, but with the same weight bike the contact pressure goes down. That's compensated by a softer rubber compound. Soft compounds wear faster (obviously) but they give more warning of an approaching slide than a hard compound so better suit a sports bike.

The other issue as he shows is the tyre shape. The very best handling will happen with a knife edge tyre as the contact remains perfectly under the bike CofG. But such a narrow tyre wont have much grip and will be affected badly by road surface (like a racing pedal bike) so we have to use wider rubber. It has to be shaped so the tyre contact remains under the CofG when the bike leans. A wide tyre on a narrow rim or narrow on a wide rim will affect all that.

A square tyre fitted on a bike handles badly because as the bike leans the contact patch moves towards the side of lean cancelling out the effect of the lean against cornering forces. The bike has to lean even more to give the same cornering speed - steering feels slow. If the contact patch could effectively move the other way, the bike will need to lean less so steering feels faster.

 

[babble]

in my opinion, anyone who tries to ride one all year round on real-world roads is kidding themselves. If we're at all honest with ourselves, that's not what it's built for.

Having ridden a Daytona 675 as my sole daily transport for 18 months, I think you'd find yourself surprised at how easy they are to live with.
Noisier than a GS (sreen)? Have you ridden a GS??!!
A GS being nearly as fast on a mountain pass? Not even nearly. A Daytona will leave the GS for dead everywhere, on any road. Riding the Daytona fast soon shows why it needs that big 190 section tyre, any why a GS does not.

The latest model GS will not have been fitted with a bigger tyre for more grip - the old size tyre was at it's maximum load rating, and the bigger tyre will allow for a heavier bike, carrying more load.

My 08 GSA ... is by far the best handling bike I have used on the road....

The bike is limited by the roads not by its ability....

This is why I'm not bothered about fitting wider rubber. It's simply not needed and it might even spoil a good overall setup.

Agreed that the GS is fabulous as a balance package, but in pure out and out handling performance, you really don't look far to find better.
I fully agree with your point about limitations - that was my main reason for selling the Daytona. It was too easy to go much faster than anyone else on the road could reasonably be expected to react to my presence. Better to ride a bike that is rewarding and fun to ride at more modest velocities.

...Within limits, wider tyres give a larger footprint, but with the same weight bike the contact pressure goes down...

The very best handling will happen with a knife edge tyre as the contact remains perfectly under the bike CofG.

It is the reduced contact pressure that is desirable, since the miu value increases slightly as the pressure reduces.

A theoretical knife edge tyre will not work well at all. The 'cone' effect of a tyre gives it side thrust and generates cornering grip - and you need width to get this effect. I'm far from an expert on such matters - but I know that much.

 

[Bendy toy]

Im talking about handling in terms of lean angle. Grip is another issue.

To get adequate grip the tyre has to be wide enough and that affects how the tyre will lean. A wide tyre should have more grip (as always within limits), but extra width causes the moving centre of contact issue that we dont have with a narrow tyre. That laterally moving contact requires a larger lean angle to give the same cornering speed as a narrow tyre. Designers come up with special profiles and rubber compounds but the basic compromise play-off between narrow width for handling and and wider width for grip dont change.

Its a compromise that explains why we wear the (rear) middle so much faster than the sides even when we are doing lots of corners. The front tyre is yet another issue as that has to generate the cornering forces that cause the bike's lean angle to change.