"Understeering" on a motorbike

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Mr Moofo
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"Understeering" on a motorbike

Post by Mr Moofo »

My old bus of a Speed Triple doesn't do it,
The Triumph Scrambler doesn't do it

But the Diavel - when cornering always wants to turn less then I want it to. (When I say understeer it is not the tyre breaking away and skipping over the tarmac, more it just doesn't quite want to go where I want it to - other than with a bit more leverage)
My guess is this could be a nature of the geometry of the bike, or suspension, or perhaps I just need to counter steer harder.
A quick google brings up MCN saying it is down to too soft front suspension ( which I would be surprised at)
My other solution would be to jack up the rear ride height.

Is there anything that I am missing ?
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Re: "Understeering" on a motorbike

Post by KungFooBob »

Tyre pressures?
Last edited by KungFooBob on Sat Jun 25, 2022 2:06 pm, edited 1 time in total.
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Re: "Understeering" on a motorbike

Post by Mr Moofo »

They are 34 front 36 back - which is more or less what the manual says ...
but good point.
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Re: "Understeering" on a motorbike

Post by Alan PBTD »

It's too light on the front - and u can shorten the wheelbase. Drop the front forks in their yokes @ approx 2mm invervals and see how she turns - max @ 6mm. It'll put more weight on the front - better grip and make it turn quicker. You could raise the rear ride height - therefore changing the geomentary putting more weight on the front but I'd put everything to std first / drop the forks and take it 1 stage at a time.
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Re: "Understeering" on a motorbike

Post by mangocrazy »

What size rear tyre/wheel does the Diavel have? From memory it's pretty massive. Too big a rear tyre tends to make the bike run wide on corner entry and also makes it harder to get the bike to turn.

My TL1000S was a bit like that. It had a 6" rear rim with a 190/50 tyre on as standard and behaved as I describe. I swapped the standard rim for a GSXR600 5.5" rim with 180/55 tyre and it went exactly where I wanted it to.
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Re: "Understeering" on a motorbike

Post by slowsider »

How wide are the bars compared to the other two? Is it maybe just leverage?
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Re: "Understeering" on a motorbike

Post by Horse »

Can you get to a dealer for a ride on another bike?

Reasons could range from stuff already mentioned to "they all do that sir".

Once in a turn, if you take any pressure off the bars, does it 'sit up' and go straight?
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Re: "Understeering" on a motorbike

Post by Mr Moofo »

slowsider wrote: Sat Jun 25, 2022 3:05 pm How wide are the bars compared to the other two? Is it maybe just leverage?
The bars are pretty wide . Leverage gets it round - but not on the track it naturally wants to take.
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Re: "Understeering" on a motorbike

Post by Mr Moofo »

However, god obviously hates me.
Just went out to use the bike to go somewhere

And I have a puncture!
Good news is it is my drive
Bad news is that no 240 rear tyres exist in the UK :-(
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Re: "Understeering" on a motorbike

Post by mangocrazy »

According to one spec sheet I've seen online, the rear tyre is an otherworldly 240/45 ZR17... :wtf:

Wider than a very wide thing and very low profile - that alone should make it steer like a barge...
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Re: "Understeering" on a motorbike

Post by Mr. Dazzle »

I've just clocked what bike it is.

I think certain expectations need to be set when comparing turn in on a Triumph Scrambler and a Ducati Diavel...
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Re: "Understeering" on a motorbike

Post by Couchy »

It’s the bike, the geometry the tyre sizes the style. Ride with a lot of pressure on the inside bar and it’ll hold a line. Ride relaxed and with a light touch it’ll understeer like loads of cruisers do even the diavel which is one of the best.

As for the tyre mates diavel has been off the road most of the year waiting for one !
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Re: "Understeering" on a motorbike

Post by Dodgy69 »

I was following a Diavel once and he wasn't hanging about, twisty B. Reckon you've just got to boss it about more than a speed triple. 👍
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Re: "Understeering" on a motorbike

Post by wull »

Couchy wrote: Sat Jun 25, 2022 8:00 pm It’s the bike, the geometry the tyre sizes the style. Ride with a lot of pressure on the inside bar and it’ll hold a line. Ride relaxed and with a light touch it’ll understeer like loads of cruisers do even the diavel which is one of the best.

As for the tyre mates diavel has been off the road most of the year waiting for one !
This but I’d recommend riding relaxed but when it comes to steering inputs for example incorporating counter steer etc you can still apply force but be relaxed, it’s when you’re not relaxed and too stiff that you won’t be able to man handle it.
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Re: "Understeering" on a motorbike

Post by Couchy »

wull wrote: Sat Jun 25, 2022 9:19 pm
Couchy wrote: Sat Jun 25, 2022 8:00 pm It’s the bike, the geometry the tyre sizes the style. Ride with a lot of pressure on the inside bar and it’ll hold a line. Ride relaxed and with a light touch it’ll understeer like loads of cruisers do even the diavel which is one of the best.

As for the tyre mates diavel has been off the road most of the year waiting for one !
This but I’d recommend riding relaxed but when it comes to steering inputs for example incorporating counter steer etc you can still apply force but be relaxed, it’s when you’re not relaxed and too stiff that you won’t be able to man handle it.
That’s what I meant, need to be a bit pro active rather than just sitting there and as you say stay relaxed
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Re: "Understeering" on a motorbike

Post by Horse »

wull wrote: Sat Jun 25, 2022 9:19 pm
Couchy wrote: Sat Jun 25, 2022 8:00 pm It’s the bike, the geometry the tyre sizes the style. Ride with a lot of pressure on the inside bar and it’ll hold a line. Ride relaxed and with a light touch it’ll understeer like loads of cruisers do even the diavel which is one of the best.

As for the tyre mates diavel has been off the road most of the year waiting for one !
This but I’d recommend riding relaxed but when it comes to steering inputs for example incorporating counter steer etc you can still apply force but be relaxed, it’s when you’re not relaxed and too stiff that you won’t be able to man handle it.
And allow time & distance, take off the mental pressure.

Slow a bit sooner, get the speed a bit lower, a little throttle open while still straight and upright so the bike is settled, grip the tank with your knees and relax your shoulders, then:
- look - point your chin where you want to go
- press - keep pressing until you get the lean angle you need

Ok, you might know all this.

But ...

The point is to go back to basics. Assuming there's nothing wrong with the bike, learn how to ride it. Take the mental 'Aaargh it won't steer' element out. Then, once it's fluid, build pace back in.
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Re: "Understeering" on a motorbike

Post by demographic »

Never ridden a Diavel but damn nearly every 80s bike used to understeer off the throttle.
Open em up a bit and they started to actually follow a line.

That was just what they did.
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Re: "Understeering" on a motorbike

Post by mangocrazy »

It's a cruiser style bike with a ridiculously large rear tyre (twice the width of the front), so it's never going to steer precisely. There are ways to mitigate this up to a point but ultimately it's all about decisions made at the design (or more likely marketing) stage that mean it's just the way it is.
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Re: "Understeering" on a motorbike

Post by Mr Moofo »

just waiting to see if I can get a new rear - going rate 230 GBP!
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Re: "Understeering" on a motorbike

Post by mangocrazy »

Allegedly available for £216.19 here:

https://www.mytyres.co.uk/search?vehicl ... eedRating=

You will need to make your own arrangements for fitting, though...
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