17" spoked front wheel on F800GS - Who's done it?

Nick V

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Hi all. :D

As per subject line: I need to get in touch with fellow (ab)users who run 17" spoked front wheels on their F800GSs.

What I have in mind is starting off with the F800GS front wheel hub as a base, and rebuilding it using a 17" rim and compatible spokes.

The trouble, as you may already have guessed, is that a) local vendors who stock the needed parts are thin on the ground, and b) most SA BMW riders have a deeper reservoir of money than of technical know-how, and are more likely to whine: "So why don't you just buy an HP2 Megamoto / KTM 990SM / Whatever?".
As a result, I don't know what brand names to be looking out for (aside from obvious ones like Excel and Marchesini).

Did anyone here complete their 17" front conversion without having to go to their bank manager with hat in hands? If so, practical advice would be greatly appreciated.

Oh, and to anyone who wants to bestow nuggets like "So why don't you just buy an HP2 Megamoto / KTM 990SM / Whatever?" as if they're original, I have one sincere request:
Don't.
Just don't.
 
While not a 17" my 19" front rim is an SM Pro Wheels item with spokes to match from the nice people at Hagon Shocks.
The nearest outlet I can find to you is in New Zealand, which isn't that close, but at least I've looked.
Does this mean that the GS/ST hybrid is back on track?
SuperTed.

Or you could just buy a......:augie
 
Ta! I appreciate it. :bounce1

A list of as many possible vendors from as many different sources as possible would do the trick - even info on El Cheapo Chinese rim suppliers, if they make what I need.
This isn't intended to be a cost-no-object/unlimited-budget project. At the moment, it's a curiosity - like almost everything else I do, I want to see if this conversion can be undertaken on an 'Impecunious Enthusiast' basis. The bike in question is a 2010 F800GS with 40 000 Km on the clock, that cost me a grand total of R63 000.
At this time, I'm not even thinking of changing fork springs - but I do propose to rebuild the front wheel all by myself.

The GS/GT hybrid was never off track. ;)
The bike that is the subject of this thread has nothing to do with that project... That one is still in my garage, waiting for the extended period of time it will take to complete it to come free.
My brother-in-law has translated the frame adaptor plate drawings to *.DWG format - they are ready to be fed into a laser cutter so the required pieces can be cut from high-tensile steel and welded to the frame.
I've decided against using the stock F800GS forks on that project. At the moment, I'm hunting for adjustable ex-KTM WP forks (or similar) that I can use. I want something quite recent, so I can incorporate radial front brakes as well. :thumb

The whole thing about people whining "Why don't you just buy bike X?"... I wouldn't mind so much if all it was, was a low-key suggestion.
But it still amazes and saddens me to see how insistent people get on that point - as if it were a debate between Catholics and Protestants about how many angels can dance on the head of a pin... :blast
 
I've done a 17in supermoto conversion, basically had a 3.5x17 morad rim laced onto the standard hub up front to suit a 120/70 tyre and a 5.5x17 rim on the rear to suit a 180/55 tyre.

I have modified forks with an extra 50mm of travel so suspension geometry remains basically the same as standard when using the SM wheels, although taller up front with standard wheels but personally i find that better off road
 
I've done a 17in supermoto conversion, basically had a 3.5x17 morad rim laced onto the standard hub up front to suit a 120/70 tyre and a 5.5x17 rim on the rear to suit a 180/55 tyre.

I have modified forks with an extra 50mm of travel so suspension geometry remains basically the same as standard when using the SM wheels, although taller up front with standard wheels but personally i find that better off road

Hi Shaun!

What you've done with the front is exactly what I have in mind.
Who did the fork mods? What exactly was done - I'm guessing longer custom stanchions, and longer springs?
Could you post a link to any pics of your bike? I'd really like to have a squizz at it. :bounce1

I'm planning on keeping the standard rear rim width and tyre dimensions, to let the bike turn more easily.
My GS/GT hybrid project will carry standard F800GT alloy wheels (3.5x17 front, 5.5x17 rear). Tyre sizes will be 120/70-17 front, and more than likely 170/60-17 rear (once again, to let the bike turn more quickly - the GT uses a 180/55-17 as standard).
 
Hi Shaun!

What you've done with the front is exactly what I have in mind.
Who did the fork mods? What exactly was done - I'm guessing longer custom stanchions, and longer springs?
Could you post a link to any pics of your bike? I'd really like to have a squizz at it. :bounce1

I'm planning on keeping the standard rear rim width and tyre dimensions, to let the bike turn more easily.
My GS/GT hybrid project will carry standard F800GT alloy wheels (3.5x17 front, 5.5x17 rear). Tyre sizes will be 120/70-17 front, and more than likely 170/60-17 rear (once again, to let the bike turn more quickly - the GT uses a 180/55-17 as standard).


I modified the forks myself basically bored out the fork bottoms and used husqvarna wr125 internals and bitubo springs,

All the info you need will be in here
http://advrider.com/index.php?threads/f800gs-rxv-shivered-fork-conversion.603554/

I'd say that the bike actually turns quicker with the 180/ 55 as its a pointier profile whereas most 150/70 have a flatter profile
 
I don't have too much time to spend on the mechanics of this, as I'm prepping the 800 for an Iron Butt run in two weeks. But what I've established so far is this:

- At R2 000, a new 36-spoke, 3.5x17" Excel front rim, laced onto a spare F800GS front hub I own, is going to be the cheapest way to go. The price includes a good set of stainless-steel spokes. I already have a spare F800GS front wheel I can rob for bits, and a good 120/70 R17 front tyre.
- Supermotos are not really popular in SA. As a result, spares are hen's teeth.
- Before the new wheel goes on, the standard front forks will be modified with longer, stiffer springs and slightly heavier-weight oil. I'll be having these springs custom-made by any of five local manufacturers.

More to come when I have some free time. :)
 
- Supermotos are not really popular in SA. As a result, spares are hen's teeth.
- Before the new wheel goes on, the standard front forks will be modified with longer, stiffer springs and slightly heavier-weight oil. I'll be having these springs custom-made by any of five local manufacturers.

More to come when I have some free time. :)

Longer springs won't really benefit you unless you are changing the damper rods/cartridges to give you more travel but even then the std springs are long enough. just need to make preload spacers to suit.
 
Longer springs won't really benefit you unless you are changing the damper rods/cartridges to give you more travel but even then the std springs are long enough. just need to make preload spacers to suit.

My thinking here is to keep the suspension geometry approximately the same as standard (taking into account the reduction in static ride height by two inches when the 21" is exchanged for 17").

As regards longer travel, the only problem I forsee is the front suspension topping out under hard acceleration, so maybe a bit more 'flighty'?
Bear in mind, this bike almost never sees off-road.

Good idea with the preload spacers, though. Sounds like the most effective solution for the least overall hassle. :thumb
 
My thinking here is to keep the suspension geometry approximately the same as standard (taking into account the reduction in static ride height by two inches when the 21" is exchanged for 17").

As regards longer travel, the only problem I forsee is the front suspension topping out under hard acceleration, so maybe a bit more 'flighty'?
Bear in mind, this bike almost never sees off-road.

Good idea with the preload spacers, though. Sounds like the most effective solution for the least overall hassle. :thumb

I don't think topping out the suspension is a good idea even for just road use, as your sag settings will be way out which could affect cornering.


Personally unless you're going to modify the forks to correct the geometry i'd just buy a 21in road tyre, I used to run a bridgestone bt45 on my kle500 and that had enough grip to mix it with sportsbikes on a track day
 
Okay, next problem....
I've managed to source a suitable Excel front rim.

But I can only find two suppliers in SA who are capable of supplying the needed spokes.
One has no listing for spokes to graft an F800GS hub to the Excel rim; the other is somewhere in Cape Town but my local goodie shop refuses to give me the name of the supplier. :mad:

Can anyone help with a spoke length?
 


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