Suspension issue

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Graham

New member
Approaching 3000 miles on my GT. I sense what feels like the forks "topping" out when riding on rough pavement, over manholes, or rippled pavement. Two dealers have checked it out and said its ok.
Just seems that a BMW should be tighter than that. I have also noticed that the handlebars start to shimmy if I let go...is that normal? My RT could be ridden no hands using cruise control.
Are these scooter characteristics that I should get used to?
 
S

Snowdog

New member
There could be many reasons, check the steering geometries of both bikes. Does the RT have a steering damper? And why are you letting go of the handlebars, and does your mother know you are doing this?
 
Eccles

Eccles

Member
Graham said:
I have also noticed that the handlebars start to shimmy if I let go...is that normal? My RT could be ridden no hands using cruise control.
Click to expand...
This could likely be tyres out of round/cupped or in need of re-balancing. As for RT, cruise and one hand lightly rested on bars, helps me get around the curves:p.
 
G

Graham

New member
Thanks for the replies. The no hands thing is not really an issue, just an observation.
I am, however, still concerned about the front end and a perceived looseness when the road is rough or hitting bumps.
 
SteveADV

SteveADV

Active member
Hey Graham...

For what it's worth, it is not a problem for me but another post from awhile back talked about feeling every bump. After 3,000 miles you no doubt have the feel of the GT vs the RT so it probably isn't the "new to you" bike difference. I rented an RT and noticed a big difference in how it handled, of course. Can't say I prefered the RT because the GT fits me so well ergonomically even though the RT is made from the ground up to do huge miles in a day.

Maybe you're just becoming more sensitive to the bumps as you age:D
 
JaimeC

JaimeC

New member
The smaller wheel diameter isn't going to "swallow" road irregularities as smoothly as a larger, more traditional motorcycle wheel. It also has less gyroscopic "resistance" to changing direction, so I can see how someone jumping off a motorcycle on to one of these puppies might find some of the sensations "strange." I know I did.
 
TwoPort

TwoPort

Member
JaimeC said:
The smaller wheel diameter isn't going to "swallow" road irregularities as smoothly as a larger, more traditional motorcycle wheel. It also has less gyroscopic "resistance" to changing direction, so I can see how someone jumping off a motorcycle on to one of these puppies might find some of the sensations "strange." I know I did.
Click to expand...

The feeling about the front suspension "topping out" was something I wondered about when I first got the bike. It felt like it was "knocking" on bumps or rough areas. After the 6K miles service, it stopped - as well as otherwise it seemed to be more smooth riding even over bumps. When I posted about what I thought was happening the consensus was I was experiencing something like "service syndrome" which was also probably true. But reading this thread I went back to the service notes and found that the dealer notes stated they "checked the steering bearings." Don't know if that is common for 6K service.

Does it seem like that process of checking the steering bearings may have resolved that the steering stem could have been loose and now resolved?
 
G

Graham

New member
The steering bearings certainly could be the/an issue, and worth a look. Maybe I'm just being too sensative, but I will say "it's fun to ride, suspension issue or not".
Thanks for all the replies, I will continue to enjoy the ride...and look for the solution.
For everyone, I can't stress enough, that I live in the perfect town (Hot Springs, AR) to own a scooter. Other than rainy days, a commute on the GT is paradise on wheels.
 
C

clayfeet

New member
It felt like it was "knocking" on bumps or rough areas.
Click to expand...

No one has mentioned the huge unsprung mass issue

https://www.youtube.com/watch?v=9FZrJBWQ7-g

Unlike conventional motorcycles, most all scooters (BMW, Aprilla, Vespa) with the variator / centrifugal clutch CVT style final drive suffer from rear-end "hop".

The late John Britten recognized this

Britten V1000 - Wikipedia, the free encyclopedia

when designing a bike that I was lucky to view (and ride alongside in practice) at Road Atlanta and Daytona.
 
SteveADV

SteveADV

Active member
Uhhh, Graham....I'm with you man, but any day is a good day to get out and ride a UMV.

And for those that haven't been there, Hot Springs (and the surrounding areas/lakes) really rock. It would be a great Central/Southeast meet up place this coming summer.
 
yellasei

yellasei

New member
the front end i would put down to steering bearings need adjusting up. also, you will find when they have been adjusted, as long as your tyres are good, the bike will steer without the shimmying you report.
 
Skutorr

Skutorr

Active member
Properly set-up, you should be able to take your hands off the bars at 50mph and engine brake to walking speed without any balance issues..
 
S

Snowdog

New member
Skutorr said:
Properly set-up, you should be able to take your hands off the bars at 50mph and engine brake to walking speed without any balance issues..
Click to expand...

Indian Larry thought he should be able to do that , and stand on the seat. May he rest in peace.
 
S

Snowdog

New member
clayfeet said:
No one has mentioned the huge unsprung mass issue

https://www.youtube.com/watch?v=9FZrJBWQ7-g

Unlike conventional motorcycles, most all scooters (BMW, Aprilla, Vespa) with the variator / centrifugal clutch CVT style final drive suffer from rear-end "hop"

The late John Britten recognized this

Britten V1000 - Wikipedia, the free encyclopedia

when designing a bike that I was lucky to view (and ride alongside in practice) at Road Atlanta and Daytona.
Click to expand...

If you look carefully and compare our BMW CVT's with others, you will see that ours are designed to minimize unsprung weight.
 
Skutorr

Skutorr

Active member
Snowdog said:
If you look carefully and compare our BMW CVT's with others, you will see that ours are designed to minimize unsprung weight.
Click to expand...

Actually, no. The CVT mechanism is incorporated into the engine, which is attached to the frame and is Sprung Weight. In front, the upside down forks minimize un-sprung weight, unlike all other scooters (until the new 2015 Tmax). In the BACK, though, it's still a chain-drive mechanism like your typical scooter. A traditional motorcycle's drive chain has reduced un-sprung weight, compared to that. Oh, and the Tmax from 2012 with belt drive...:cool:
 
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