19inch vs 21inch

[Alang]

Can someone tell me what the advantages of a 21inch front wheel has over a 19inch on a dual purpose bike and why?

[Warthog]

I'm no expert but generally I believe that the smaller diameter makes for easier and quicker steering on the road, whilst the larger makes shorter work of obstacles off-road as well as not getting as stuck in mud/sand etc.

I'm sure there are more in-depth reasons that will follow. Tyre choice is a pratical issue to consider: stickier rubber for 19s and more knobbly profiles for 21s...

[Pigford]

The larger the diameter of the wheel, the better it'll cover rough ground (smooth out the bumps & pot holes).
Honda did try 23" on the old XL's but that didn't catch on... just a bit too big!

[Tony P]

Originally Posted by Warthog

Tyre choice is a pratical issue to consider: stickier rubber for 19s and more knobbly profiles for 21s...

Not just tyre type - consider tyre size availability too.

For example, BMW's F650 has a 17 inch rear - not a very common size in remoter parts of the World where other sizes are more usual.

[*Touring Ted*]

21" front is for offroad bikes

17" is for road bikes...

The 19" was meant to be a happy medium between them both. Offering a compromise of handing and offroad capability/handing.

A 19" is nice but sadly tyre choice is very limited, especially out of the western world.

I've had no problems with road handling on 21" wheels but try taking a 17" wheel offroad !! Not fun (and i've done Supermoto offroad)

[Mick O'Malley]

21" has three advantages: 1) As above, the larger diameter rides road imperfections better. 2) The thinner tyre section bites better on loose surfaces, giving stronger castor action and 3) The larger diameter increases the wheel's gyroscopic effect which means it's not only more difficult for road imperfections to deflect it, but also it returns more strongly after deflection. IMHO, having ridden dirt on my GS1100 (19") and my current Honda Dominator (21") I would say there's no contest in the controllability stakes.

Regards, Mick

[*Touring Ted*]

yeah.. sadly, like most things in life ! More inches the better