OK you Adv gurus, can you please explain this:

[XF650]

I had the pleasure of riding the gravel route from Tuakau to Raglan yesterday, sharing rogson's Freewind & DRZ480SM (thanks again Roger). This was the DRZ's maiden gravel ride and we saw some great country but man was it dry, considering it's the NI West Coast. In fact it reminded me of how North Otago was looking just last week.
Anyway what really surprised me was how bloody well the DRZ coped with the gravel, especially as it was shod with the std "motard" wheels & fat slicks. WTF!! This thing just blew away my two best excuses for being a shit gravel rider i.e. small front wheel & not enough grip. OK I admit that things might have got a bit hairy in an emergency braking situation. But we were still both surprised at how well it hung on in gravel (faster test by the owner, slower test by me).
So how does it do it? All we could think of was perhaps trail bike geometry and sticky rubber.
Any other ideas?

[Padmei]

Good question. May I add to it and ask what characteristics do smaller wheels have on gravel compared to the 21 inch? Apart from going over objects easier.

[Willdat?]

Good question. May I add to it and ask what characteristics do smaller wheels have on gravel compared to the 21 inch? Apart from going over objects easier.

From my limited gravel riding experience, the 21" fronts are usually narrower and 'cut through' the loose top layer.

My motard with 17" wheels (50 cc Suzuki SMX...) kind of skimmed over the top which didn't exactly inspire confidence. The compounding factor in this was probably the bikes light weight (sub 90kg).

I never took my DRZSM on gravel ops: so can't comment that way, it was too shiney!

[NordieBoy]

A motard on gravel is more "riding on ball bearings" than a knoblish shod machine. Mainly due to the width of the tyres.

The 17" front makes it a bit twitchy compared to a 21" but I took the Nordie through the Rainbow no issues and that was before I learned to ride gravel and didn't know what I was doing.

I think with the right bike (geometry/weight/tyre pressure) gravel can be good fun.

On the wrong bike however...

[Transalper]

Comparing the Freewind to a DRZ480SM is probably more about the rest of the bike than just the wheels.

[XF650]

Comparing the Freewind to a DRZ480SM is probably more about the rest of the bike than just the wheels.

Fair comment although we weren't really making a comparison, even though the XF is well sorted with mods to suspension, jetting, 21" front etc.
Performance aside (that 480 kit is awesome), the main surprise for us was how much control the motard wheels & tyres had on (dry) gravel. It wasn't "twitchy" & even crossed the mounds OK.
I suppose the good power to weight ratio makes it easier to "point & squirt", but there must be other reasons why it went so well on gravel. It was a revelation for me anyway.

[Motu]

After thinking a 21in front wheel was the only way to ride gravel for more than 30 years,I have changed my mind - with the right tyres my R65 streettracker is better on gravel than an ADV bike.Weight distribution (more on the front,lower CG) and some hefty trail make the front end very stable,and the square section K70's get down to the surface.I've experimented with riding corners right in the thick stuff between wheel tracks - tracks straight and true,and can power out in a slide without the front moving an inch.

[Transalper]

eeeek Motu that's terrible news for an avid fan of the 21" such as myself. Next you'll be telling us the world isn't flat too.
It is however something to consider when time comes time to change bikes, that possibly some bikes may simply work just as well or even better with the horrible small fat wheel.
Only thing left to do is discover which ones... and whether they still work on other surfaces.

[PeteJ]

Probably the best gravel road machine for control I've ever ridden was a 1974 Honda 350/4, with a ribbed 18" front tyre. The low centre of gravity did more for it than a 21" front wheel on any machine, IMHO. My mate Dice was 2nd in a Shell 800 on that thing.

Its short-travel suspension did nothing for comfort on gravel - but the offset to that was a really smooth gutless motor that was a comfort advantage as well as being great for controlled wheelspinning.

[Eddieb]

Brother in laws CB750 used to seem nice and stable on gravel too. I think the 21"inch comes into it's own when you are going through rougher surfaces like rocky terrain, up and down banks, larger rocks, soft sand and gravel etc. On a gravel road it's not so important.

[XF650]

I don't think low COG applies to a DRZ SM !! And remember we are only talking gravel, not off road.
Any other ideas?

[george formby]

I don't think low COG applies to a DRZ SM !! And remember we are only talking gravel, not off road.
Any other ideas?

Weight? I would wager the DRM doe's not load the front to much making it feel stable, particularly under power. My bike has an 18' front & feels great on the gravel until I have to brake excessively or load the front through downhil corners. All of a sudden I'm riding a 200kg bike on sports touring tyres again. A bit of throttle fix's it.l

[Motu]

The CB750 is the worst bike I've ever ridden on gravel,so over weight and top heavy it was really unstable.Trying to work out why the R65 is so good on gravel,I think one of the most important is the amount of trail - 120mm,nearly 4 3/4 in for us old fellas.This gives stability,and in thick gravel stops the contact patch getting ahead of the steering axis.Also for getting some speed on gravel,the short stroke light flywheel engine really hooks up and drives.For instance the XT600 would wheelspin soon as the throttle was opened,and just keep on spinning...even on the hardpack,regardless of tyres.The R65 with only 27 more cc and 4 more HP is a much faster bike on seal and gravel - it will still wheelspin in the loose,but takes a lot more throttle to do so,but when it hits some hardpack it just hooks up and is gone.I can really ride this bike hard and fast....the XT600 and DT230 were just surfing on wheelspin.Getting hooked up is the way to go forward.

[bart]

I used to run 18 inch road wheels on the DRZ400, with road tyres. It used to handle the gravel alright. Back would spin up real easy, but the front was fairly planted in most situations (without going silly). Get the tyre pressure right, and it's no drama. Certainly preferred the bight of the 21 inch with a semi knobbly though.

But hey.....I also rode a lot of gravel on a ZX9R. That was shithouse. You certainly learn throttle control with 140hp on tap.

[PeteJ]

To return to the orginal question, why a motarded DR-Z400 should go so well on the Waikorea Coast road (know it well; I have a bro-in-law farming there).

1. It's a dry gravel road. You don't need a helluva lot of grip through the surface.

2. A bit of gravel rolling under the wider tyres will help you ride smoother, anyway.

3. You sure don't need a huge rolling diameter on the front wheel for gravel riding.

4. The good supension travel makes you feel comfortable, which helps a lot, as does the seating position.

All opinion, of course (just informed by 45 years of gravel road riding; we used to live at the far end of a 40-mile gravel road when I got my first bike).