Adventure Supermoto

[Greenman14]

I'm interested in the 17" front wheel but don't like the idea of a rear wheel offset. I also think that maybe the GS doesn't needed a 180 section back tyre.

Any suggestions for tyre sizes front and rear 17" with the original back wheel? My old CBR 600 managed quite nicely with a 160 rear and c100bhp.

 

[Bendy toy]

Mine is running standard GS wheels while the wires are stripped and powder coated. TBH the alloys suit it very well and while they wont give the handling of a 17" front and fat rear tyres its pretty damn close.

Few riders on "normal" bikes can keep up with a well ridden GS. When I'm pressing on, the few riders who get by are complete nutters happy to overtake on blind bends.

 

[Nick V]

I'm interested in the 17" front wheel but don't like the idea of a rear wheel offset. I also think that maybe the GS doesn't needed a 180 section back tyre.

You're right: it doesn't need it - in the same way that the BMW M5 doesn't need another 40 BHP with every new generation.
However, if you do want it, it is nice to have.

Re. the offset: I've had the opprtunity to compare an R1200RT rear wheel and K1200S rear wheel back-to-back on the same GSA.
Oddly, it's the R-series wheel that has the most offset. The K-series wheel seems to be tracking more-or-less dead straight.

From what I hear on the grapevine, the R1200S wheel has the same offset issue as the R/RT/ST-pattern wheel. I can't confirm this, since I don't have an R-S wheel handy.
But since the K-series rear seems to track straighter on the GS, why not try a 'standard'-pattern (K1200/1300GT, K1200/1300R) or 'turbine'-pattern (K1200/1300S) K-series rear?

Any suggestions for tyre sizes front and rear 17" with the original back wheel? My old CBR 600 managed quite nicely with a 160 rear and c100bhp.

It can be done - only thing is, you're going to sit with two very different wheel designs on the same bike. I don't know how you'd feel about that. Personally, it's not something I'd do, but to each their own.

If you want to go that route, it obviously hasn't been documented by BMW (nor, I think, by anyone else here), so the best thing to do is experiment.
You must bear in mind that each tyre width/aspect ratio is deliberately designed around a rim of specific width. 5.5-inch rims accomodate 180-section tyres happily. 6-inch are meant to accomodate 190-section.

For the standard-width rear rim, you're pretty much stuck with a 150-section. You could go up to a 160-section, but I wouldn't recommend it - you're risking possible handling quirks (mainly due to excessive latitudinal sidewall flex.).

The best-looking way to go about your chosen route might be to stick with an original rear GS wire wheel, but use an original front hub and discs in concert with an aftermarket 17-inch rim and suitable spokes. (Since these are commonly available for supermotos, they shouldn't be difficult to get. ) To the best of my knowledge, no one has yet done this - so you'd have something truly unique.

 

[DING-DONG]

The best-looking way to go about your chosen route might be to stick with an original rear GS wire wheel, but use an original front hub and discs in concert with an aftermarket 17-inch rim and suitable spokes. (Since these are commonly available for supermotos, they shouldn't be difficult to get. ) To the best of my knowledge, no one has yet done this - so you'd have something truly unique.

Its has already been done Pidcocks had a rallye that had a relaced 17" front wheel, the rear wheel was stock spoked.

 

[Neil W]

For the spoked look find a set of r1200r classic wheels

 

[Nick V]

Its has already been done Pidcocks had a rallye that had a relaced 17" front wheel, the rear wheel was stock spoked.

Oooooo.
Now that, I would like to see a pic of...

 

[Nick V]

For the spoked look find a set of r1200r classic wheels

The R1200R Classic was never sold here...
What are the rim widths front and rear?

A fellow I work with owns an R1200C. About a month ago, I was eyeing his wheels and wondering if THAT might work.
But with a 15" rear and 18" front, thoughts of 'Moto-ing will get you nowhere...

 

[Bendy toy]

The suggestion of a 160 rear tyre instead of the stock 150 had me thinking. (dangerous I know)

It "might" cause handing quirks, but having fitted one to a Yamaha Diversion 900 that normally uses a 150 rear tyre the only palpable difference was the gear ratio dropping a few percent. The 160 had a smaller aspect ratio than the 150 so even crimped slightly by the narrower rim it gave a reduced rolling radius. It wasn't much but unwelcome on an already under-geared bike. The GS might be less of an issue with its 6th gear.

The handling was considerably better but that's because I was running much more sporty rubber than normal.

The universal wheel offset spacers mentioned earlier might be fine. However they wont have the locating lip the standard wheel carrier has. Tighten the wheel bolts VERY evenly and check for run-out at the rim. A custom spacer could be made with a locating lip avoiding the problem but as ever presenting others.

 

[Deleted account 211025001]

My experience of running 160's on a rim meant for 150's is limited to SMs - no real advantage that I noticed but defo a bit slower steering and not a very linear feel to tipping in - no great shakes really but as I said, no real advantage.

I now run 160's on the correct sized rim and the above traits are gone other than very slightly slower steering which is easily compensated for by raising the forks in the yokes (not something you can do on a GS).

Andres

 

[Nick V]

The R1200R Classic was never sold here...
What are the rim widths front and rear?

A fellow I work with owns an R1200C. About a month ago, I was eyeing his wheels and wondering if THAT might work.
But with a 15" rear and 18" front, thoughts of 'Moto-ing will get you nowhere...

Well, a quick poke around the internet for R1200R Classic info revealed the following:

Front Wheel Width: 3.5 in.
Rear Wheel Width: 5.5 in.
Front tyre dimensions: 120/70-ZR17
Rear tyre dimensions: 180/55-ZR17

So, identical to standard R1200R, RT and ST.

...Now, someone with foresight needs to pick up their tools, and build it.

 

[Greenman14]

Looks like the tyre combination would be 110/70 17 front and 150/70 17 rear. Only difference is the standard front is an 80 aspect ratio tyre so the 70 should give a more rounded profile and slow the turn-in?

 

[Nick V]

I'm afraid I have some bad news for you...

Looks like the tyre combination would be 110/70 17 front and 150/70 17 rear. Only difference is the standard front is an 80 aspect ratio tyre so the 70 should give a more rounded profile and slow the turn-in?

It doesn't quite work that way.
Remember, if you're not going for a 'moto conversion purely for image reasons, the point isn't just to gain quicker turn-in; it's also to be able to take advantage of more aggressive tyres for more grip.

A quick search of my local retailer unearthed the following in 110/70-17:

• Kenda Cruiser
• Metzeler Lasertec Front
• Michelin Pilot Activ Front

Neither of the first two are exactly state-of-the-art - they're designed for very mediocre cruising/commuting applications. The Activ is sportier, but designed for much lighter bikes such as 400 4-strokes.

The tyre manufacturers consider 150/70-17 mainly a 'dual-sport' category - which means that 90% of what you'll find in this size is meant for big trailies anyway. The 'sportiest' tyres I managed to find were the Tourance EXP and Pilot Road 3.

So, the sizes you mention make the conversion essentially self-defeating - you'd be better off sticking with what you've got.

I have a hunch that you may be trying to try this on too tight a budget. I'd urge you to consider at least a 3.50in rim and 120/70 tyre at the front, and a rim that will enable you to take at least a 170/60 at the rear.
This will let you use tyres that can take advantage of the better turn-in by letting you hold a line without sliding.

 

[Bendy toy]

Front tyre dimensions: 120/70-ZR17
Rear tyre dimensions: 180/55-ZR17

Those are the easily available tyre sizes when buying pairs.

For example http://www.mandp.co.uk/productinfo/536138/Tyres/Road-tyres/Continental

 

[Deleted account 211025001]

.................
I have a hunch that you may be trying to try this on too tight a budget. I'd urge you to consider at least a 3.50in rim and 120/70 tyre at the front, and a rim that will enable you to take at least a 170/60 at the rear.
This will let you use tyres that can take advantage of the better turn-in by letting you hold a line without sliding.

Whilst what you say is true to an extent it's pretty theoretical, in the real world there are plenty of sticky tyres in those sizes which are more than capable of out performing most riders.......

Random examples would be Avon Storm2 Ultra or Dunlop Sportmax Mutant

Andres

 

[Nick V]

Those are the easily available tyre sizes when buying pairs.

For example http://www.mandp.co.uk/productinfo/536138/Tyres/Road-tyres/Continental

+1. That's another important consideration when going for non-standard wheels/tyres - what sort of tyre availability is there in your chosen size(s)?

Since 120/70-17 and 180/55-17 are the 'baseline' sizes for 600cc supersports, England is pretty much guaranteed tyre supplies for the forseeable future (barring an asteroid strike).

 

[Nick V]

Whilst what you say is true to an extent it's pretty theoretical, in the real world there are plenty of sticky tyres in those sizes which are more than capable of out performing most riders.......

Random examples would be Avon Storm2 Ultra or Dunlop Sportmax Mutant

Andres

Ugh. I don't know how this little third-world People's Republic I live in ended up with a virtual monopoly by Michelin with everyone else fighting for the scraps, but all Avon tyres, most Dunlops, and plenty of others are unobtainable here.
Most South Africans have never even heard of Pneumant.

Track-day tyres? Nearly all are Metzeler Racetec and Pirelli Diablo Supercorsa, with a (very) slight sprinkling of Dunlop D211.

Another weird thing: 170/60-17 rear tyres (in road/sport configuration) are almost pure unobtainium here.
Dog help you if you have a bike with a 5.00" rear rim: you'll be forced to choose between 160/70 or 180/55. I first encountered this problem when I owned an R1100S.

 

[Deleted account 211025001]

Ugh. I don't know how this little third-world People's Republic I live in ended up with a virtual monopoly by Michelin with everyone else fighting for the scraps, but all Avon tyres, most Dunlops, and plenty of others are unobtainable here.............................

That's really pants, lots of choices here in Europe - surely that has to be a good excuse to do some group buys of tyres with your mates, shipping shouldn't be too bad spread across a decent order

Andres

 

[Nick V]

That's really pants, lots of choices here in Europe - surely that has to be a good excuse to do some group buys of tyres with your mates, shipping shouldn't be too bad spread across a decent order

Andres

The trouble here is that corruption - leading to jealously-guarded profit monopolies - is omnipresent.

Doing that is a great idea in theory, but in practice, importing direct means that prices at the prevailing Rand/Dollar exchange rate go from 'eyebrow-raising' to 'horrific'. And because no one manufactures bike tyres locally here, there are no local-content points for them. So whack some extra import duties on top of that.

You could get around this by signing a franchise agreement with a manufacturer. But to bring the price down to levels below retail means buying so much stock that you'd be better off becoming a full-time tyre merchant. And even then, the established fitment centres here have so much of the market that there's no guarantee you'd succeed.

The business ethos here seems to be: "I don't mind competition - as long as I don't have any."

 

[Deleted account 211025001]

The trouble here is that corruption - leading to jealously-guarded profit monopolies - is omnipresent.

...........................

Feel for you

Andres

 

[Greenman14]

Fair point about doing this on a budget, but my other consideration is I don't like the offset rear wheel on principle. And the full conversion is 2 wheels plus a new exhaust as the standard one doesn't have clearance for the wider tyre. Agree that 120 front and 180 rear is a good combo and gives loads of choice.

Ps not doing this for the looks of it, just want the handling, and lower seat height is a bonus as well.