Lacing a 19" rim onto f800gs front wheel

[Alan R]

This is probably no more than idle musing on my part.... I'm wondering if it is practical to fit a 19" rim to the existing hub of my f800gs. My reasons are to have a greater tyre choice and wider profile than the existing 21" rim allows.
I don't know what effect such a change would have on the abs setup as the rolling diameter of the new tyre would be less than that of the 21" wheel.
The owners manual does mention such a change and refers one to a dealership to effect a change to the abs control parameters.
Again, I don't know if is actually possible and the reference will end in a negative response from the dealer, simply because they have never done it before.
Any experience or thoughts?
Alan R

 

[Schtum]

It's certainly been done before, as indeed has fitting a 17" front wheel. From memory, going to a 19" front doesn't increase the front wheel speed enough to upset the ABS. However, I very much doubt that you'd get a BMW Motorrad dealership to do the work as it's unlikely to be approved by BMW and therefore they wouldn't be able to warrant the work. You'll need to find an independent wheelbuilder who can lace a 19" rim onto your existing hub or find another hub to have onto which you can have the rim laced.

You'll find that fitting a smaller wheel will steepen the steering head angle a bit and the bike should turn more quickly than it does with the 21" wheel.

You'll also find yourself magically transformed into a stunt rider....

<iframe width="560" height="315" src="https://www.youtube.com/embed/btRvVLA0KzM" frameborder="0" allowfullscreen></iframe>

 

[Alan R]

Oops!

 

[Alan R]

From memory, going to a 19" front doesn't increase the front wheel speed enough to upset the ABS. However, I very much doubt that you'd get a BMW Motorrad dealership to do the work as it's unlikely to be approved by BMW and therefore they wouldn't be able to warrant the work. You'll need to find an independent wheelbuilder who can lace a 19" rim onto your existing hub or find another hub to have onto which you can have the rim laced.

You'll find that fitting a smaller wheel will steepen the steering head angle a bit and the bike should turn more quickly than it does with the 21" wheel.

You'll also find yourself magically transformed into a stunt rider....

there's not a lot of abs going on in that video! I've just measured from axle centre to the floor on my r1200gs and compared it with the same on my f800gs. The 800 sits less than 1/2 inch higher off the ground so the head angle should not be an issue. The rolling diameter difference would seem to be about 6" greater on the rim diameter alone, but the tyre profile seems to suggest that in reality it may be less.
I wasn't considering having the work done by a dealer so warrantied work is not an issue. My only concern was if a dealer would be able to reprogrammed the abs to accept a different size wheel. I seem to be answering my own question and together with your response Schtum, think that this is viable.
Alan R

 

[JJH]

Is the wheel from the f700 not 19inch? Would that not be an easier way to achieve a 19 inch front wheel. I think that if I was going to the trouble of getting a new rim laced to the hub on my 800GSA I would be trying for a setup that would allow me a tubeless option. The same as 1200gsa. JJH

 

[Alan R]

Fair point, but then I would need to do the rear wheel too to match. Also, I don't know if the disc carrier bolts and abs sensor ring from the 700 are compatible - bear in mind that the 700 has conventional forks.
Alan R

 

[Dean]

I'm sure where there's a wheel there's a way

 

[mrjim130]

If you were to use the 700 wheels you would have the added befit of tubeless tyres.

 

[JJH]

If you were to use the 700 wheels you would have the added befit of tubeless tyres.

That's the point I was trying to make. We seem to sacrifice a lot for the "benifet" of spokes. JJH

 

[Alan R]

As stated earlier, I don't know if the 700 front wheel is compatible with the upside down forks of the 800. I'm not one of those people who is anxious about tubed tyres - I used them throughout the 1970's when there was no choice.
Alan R

 

[JJH]

So did I. First bike was a Honda 125SS a little twin that was mersesslessly trashed and then trashed 2 up to most corners of Ireland. I was 16 and didn't have a clue. I got so good at mending punctures that I didn't bother to take off the wheels. (Try that today.) It would have been better to straighten out the bashes on the rims and stop the spokes puncturing the tube. The amount of time I spent fixing them. And sliding down the road as the tube finally lets go in exerpation. Tubeless please. JJH

 

[Alan R]

Had a measuring/calculation session today and discovered the following:-

800 front tyre circumference is 84,3/4" with a 3,1/2" tyre width. Axle centre to floor is 13,1/2".
Rear tyre circumference is 80" with a 6" wide tyre.

1200 front tyre circumference is 83" with a 4" wide tyre. Axle centre to floor is 13".
Rear tyre circumference is 80" with a 5,1/2" wide tyre.

All of this leads me to consider that as Schtum said, the difference of 1,3/4" front tyre circumference will not confuse the ABS or ASC.
So, a hub, spokes, rim and wheel building costs in addition to tyre and tube will let me use a greater range of tyres and have a bigger contact patch on the front which will reduce the twitchy wandering feeling sometimes experienced at higher speeds on windy conditions.
This feels like a winter project when the current tyres are ready for replacement.
Alan R

 

[Dellis]

21" front gives plenty of grip....

<iframe width="560" height="315" src="https://www.youtube.com/embed/Zj-o_z5NyPE" frameborder="0" allowfullscreen></iframe>

 

[Micky]

21" front gives plenty of grip....

Indeed ... never had a problem myself in over 114,000 miles with the F800GS

While the 'footprint' might be slightly narrower it is also slightly longer

Can't see what all the fuss is about misen

 

[karlp]

Is the wheel from the f700 not 19inch? Would that not be an easier way to achieve a 19 inch front wheel. I think that if I was going to the trouble of getting a new rim laced to the hub on my 800GSA I would be trying for a setup that would allow me a tubeless option. The same as 1200gsa. JJH

Kineo wheels

Tubeless
Spoked
19 or 21

That is what I am putting on mine but I am sticking with the 21 front

 

[Alan R]

as I stated in my original post, just idle musings really, I always felt that the handling suffered in comparison to my r1200gs. Having fitted hyperpro springs fore and aft which vastly improved the handling, I wondered what to do about the tendency for the Anakee tyres to twitch and break contact on white lines and over banding. I tend to set tyre pressures to 36/42 on my bikes but believe that this does not suit the Anakees and have reverted to manual recommended pressures: not much improved, hence my musings.
One thing that did improve my confidence in the bike was to take it to the TT for a week and throw it about over there for about 500 miles. Much happier now but still not sure about the Anakees.
Alan R

 

[SuperTed]

I have a 19" rim on the front of my 08 F800GS and the improvement in the handling is very much worth it. Having only ridden the bike a couple of times before changing the rim I was actually starting to have doubts but due to circumstances beyond my mechanical knowledge (see my thread about battery life) I had to hire a standard F8GS for our trip round France and the difference in the handling is obvious when you ride the two 'back-to-back'.
The difference in rim circumference has no effect what-so-ever on the ABS. As the nice man at Hagon's said: it doesn't change the speed the hub spins at, and that's where the sensor is.
SuperTed

 

[Schtum]

As the nice man at Hagon's said: it doesn't change the speed the hub spins at, and that's where the sensor is.

The nice man at Hagon's is wrong. With a 19" front wheel on which the tyre has a smaller circumference than the 21" tyre and wheel combination, of course it increases the wheel RPM in comparison with the original front wheel at any given road speed. However, that increase appears to be with the parameters of differential front / rear wheel speeds which the ABS system can cope with.

 

[shaunj]

I'm currently running a 17in front on my road wheels. This is enough of a difference to cause the ABS to have a moment when you brake heavily. Basically lose the brakes for a moment until it decides to turn the ABS off. Now I just turn it off before each ride or you could just disconnect the sensor if you're forgetful, Whether the 19in makes enough of a difference to affect it I can't say.

As for steering angle I have 50mm longer forks so the bike sits the same as a 21in with std suspension. When I first did the set up I had the front lowered about 1in and found that when cornering at speed the front felt like it wanted to wash out.