Last week I was on a road trip to southern Utah. While stopped waiting in a parking lot for the rest of my group, I was holding the rear brake as I was in neutral on a slight incline. I grabbed the front brake lever and with both brakes applied and standing still, the idle changed a little and the bike seemed to shake more. Release either the front or rear brake and the idle goes back to normal. Grabbed them both again and it shook again. I repeated this a few times.

All I can think of is actuating both brakes engages the ABS and that may be the reason why. It's probably normal and nothing to worry about, just curious if anyone else has noticed this?

 

it could be a weak battery...when you pull the brakes it turns the brake lights on which loads the elec. system, which draws down the voltage, which causes the stator to ramp up, which loads the motor and slows it down...usually the battery will provide the extra current/voltage, but if the battery is weak the stator needs to provide the elec..

 

The vibes from the bike are usually transfered to the front wheel which is ever so slightly rocking back and forth, if the brakes are applied the tire can't rock back and forth on the ground so the vibes are transfered to everything else. I'm not sure if I'm explaining it right but if you've ever noticed a Harleys' front end shake at idle you know what I'm talking about.

 

This is exactly it. It's completely normal to feel more vibes while sitting still if the front brake is applied. Not sure about the rear brake as I've never noticed it, but definitely feel the vibes with the front applied. And the idle speed - that shouldn't change.

 

Just coincidental timing of an earthquake.

 

That sounds reasonable. Thank you.

I didn't think there was anything wrong with the bike, just something I guess I haven't noticed before.

 

+1 (look at larger off road bikes)

 

I had a 1977 Yamaha TT500 "Thumper" and if I let it idle on the carport for more than a minute or two it would start to walk away, vibrating/dragging the kickstand as far as 10-15 feet depending on how amusing it was to me at the time. The front tire wobbling a good 1/2 back and forth the whole way.

 

This is the answer! 100%

 

A couple of good explanations here. Sounds like no reason for worry. I'll have to look for that on my ride -- interesting!