Wheel sizes? Scrambler build

[littleslip]

Looking around people seem to use different combinations of wheels for their scramblers.

I'm going for that triumph scrambler look.

I've seen 17 rears with 18 front.

17 rear, 19 front

even 17 rear 21 front.

What sort of width rims are people using for both? Was thinking 3.5" rear but not sure about the front?

I have a Harley sportster rear hub to lace up, was going to look out for a XS front hub with a modern single disc set up, probably R1 or the like.

Thoughts? Experiences?

On top of that I've got to consider the rear tyre size for clearance issues etc. I've got hold of an XJ600 swingarm to put in. First looks are it just needs some spacers making up as its smaller at the pivot than the XS arm. Then sort some buses out to take the XS swingarm bolt.

Thanks

 

[arcticXS]

For a single disc front wheel, I would recomment a Virago 535 front hub. Just like an XS hub, except for only 1 disc mount flange. Cleaner looks, possibly less weight (?) and no need for the trim ring to cover up the unused disc mount holes. Maybe even easier to find than an XS front hub.
I guess you may know this already, but a 17" rear rim will lower your gearing, unless you use a very tall tyre. I had a custom rear wheel built with a 2.50x18 rim, but I already regret not getting a 19" Modern MXers use 19" rear tyres, as well as the flat trackers, you can even get K81 in 19" rear tyre sizes. A larger rear wheel gives more freedom to play with gearing/ sprocket sizes, which is especially handy if you wish to use long shocks.

 

[littleslip]

I don't think 19" front and rear would suit the look I want to be honest. Can the gearing not just be adjusted for with different sprockets? I may have to have a custom sprocket made up anyway to suit the sportster hub.

Like the Virago hub idea will keep an eye out? Have you done this mod? I imagine an adjuster ring will need making up to suit a modern disc

 

[arcticXS]

The Virago hub has the same disc mount dimensions as the XS hubs, 6 bolts on an 80mm centreline circle.
The required disc spacer ring depends a bit on which disc and caliper you plan on using. The common 320 Brembo (Ducati) discs have a 10 mm offset, and will need a spacer between 10 and 13 mm thick, depending on caliper.
On my 77D, I ordered a custom ISR disc with 23 mm offset, so no spacer required. This disc has between 1 and 2 mm clearance to the fork slider, so is close to the limit.
MotoLanna have both 10 mm disc spacers and caliper adapter for the 4-piston Brembo caliper with 40 mm between mounting lugs. Nice machined alloy parts.
Regarding rear wheel and sprockets. Most other hubs will not allow the small(ish) sprockets that is preferred by most. Also, a small rear sprocket will lead to the chain rubbing on the swing arm, especially when longer shocks are used. Since you plan to build a Scrambler, I assume you also plan on a bit longer shocks

 

[GreasyC]

Old bikes had the front wheel taller than the back, while modern looking bikes have the opposite. Off-road bikes have an even bigger difference in size with the front rim commonly over 20". A scrambler is both an old and off-road styled bike so if that's the look you want you're looking for taller front than back. Note that the visual height is dependent on more than rim size. If you make both rims the same size the rear will look taller because of the thicker tire. You usually need to make the front rim at least an inch larger just to make the tires look equal height.

Don't start by thinking about rim sizes, start by shopping for a tire set, and when you settle on one that gives the look you want check the manufacturer's recommendation for ideal rim to run it. The catalog will have ideal rim size + acceptable limits either side.

 

[db1337]

Just for your reference, here's my build in progress with 18 rear, 19 front...

Update:
Can't post pic, site crashes on my iPad when I click on the photo insert button.

 

[littleslip]

Old bikes had the front wheel taller than the back, while modern looking bikes have the opposite. Off-road bikes have an even bigger difference in size with the front rim commonly over 20". A scrambler is both an old and off-road styled bike so if that's the look you want you're looking for taller front than back. Note that the visual height is dependent on more than rim size. If you make both rims the same size the rear will look taller because of the thicker tire. You usually need to make the front rim at least an inch larger just to make the tires look equal height.

Don't start by thinking about rim sizes, start by shopping for a tire set, and when you settle on one that gives the look you want check the manufacturer's recommendation for ideal rim to run it. The catalog will have ideal rim size + acceptable limits either side.

Thanks, didn't think of that

 

[littleslip]

Just for your reference, here's my build in progress with 18 rear, 19 front...

Update:
Can't post pic, site crashes on my iPad when I click on the photo insert button.

Shame, I'll inbox you my email