Ok experts, figure this out

[FROSTY:Me]

One of my shop bikes is a boulevard 800 with a great big 21 inch front hoop.
Riding it at 30mph/50kph I start to turn into a corner. well ferk me I turn the steering in the direction I wanna turn.
Nahh that can't be right -Next corner --sure enuff 50km/h steering turned into the corner like a car.
so what happened?

[FJRider]

With the 21 inch hoop, its not getting/giving the gyro effect of a 16 inch'er... slower RPM, taking longer to do one full revolution of the front wheel...taking longer to turn corners...

[GaZBur]

I noticed the same thing today with the DR650 after changing from 17in motard to 21in dirt rims for the gravel hillclimb tomorrow - unnerves me every time. It feels the same as the VX800 which had a longer rake and the same problem despite not having a bigger front rim. The rake of the VX is probably similar to a Boulevard and it only seemed to improve over 80kph.

[mnkyboy]

One of my shop bikes is a boulevard 800 with a great big 21 inch front hoop.
Riding it at 30mph/50kph I start to turn into a corner. well ferk me I turn the steering in the direction I wanna turn.
Nahh that can't be right -Next corner --sure enuff 50km/h steering turned into the corner like a car.
so what happened?

My lil cruiser does the same thing and thats a 17" wheel - rake would be about the same

[Chooky]

If you mean it falls into the corner.......?
Pump your tire up.....

[ajturbo]

same thing happens when i was riding "shorty legg's custom..!!!!

[BAD DAD]

Does it feel like steering a penny-farthing?

[smoky]

It feels the same as the VX800

Who'd want to buy one of those

[madbikeboy]

You checked your tire pressures and your steering head bearings?

Or are you riding a trike?

[pzkpfw]

It won't be a gyroscope thing (which I think is a myth anyway).

The larger diameter wheel is going the same speed at the edge as the smaller wheel (at the same road speed) - which should give it more gyroscope effect (due to that larger diameter - the mass at the edge is further from the axis of rotation).

I'd say it's because the different diameter changed the point on the road that the steering axis (the line through the steering head) points at; and this will also change the shape of the tyre at the point of contact, in relation to the turning effect.

[Crasherfromwayback]

You should try riding a chopper with HUGE rake...they try to rip the bars outta your hands turning in at low speed.

[HenryDorsetCase]

"chopper flop" is a function of caster angle (if I recall a Kevin Cameron column about steering properly)

[Motu]

You should try riding a chopper with HUGE rake...they try to rip the bars outta your hands turning in at low speed.

Definitely the rake - I used to ride a mates BSA chop back in the '70's that flopped the front 90 degrees,it was a shit of a thing at low speeds trying to control the flop.Certainly not the 21in wheel,off road bikes are renowned for their low speed handling.

[Crasherfromwayback]

Definitely the rake - I used to ride a mates BSA chop back in the '70's that flopped the front 90 degrees,it was a shit of a thing at low speeds trying to control the flop.Certainly not the 21in wheel,off road bikes are renowned for their low speed handling.

You know it! Lucky you've still got all (I'm asuming you do) of your limbs!