no-hands balance: what makes a bike squirrely?

[teamgomez]

Great feedback, fellas. Appreciate your thoughts and thanks for the advice, Roadhouse...

Checking out Cornell's site...thx!

~John

 

[BicyclingGuitar]

I also have a '77 Sportabout. I understand that green color was the only one offered that year, and the only year it was offered.

Yes it is a fun bike to ride! If you want to share photos and info on the internet about it, I could host a page or two about your bicycle on my web site. Please email me if interested.

They made them in '78 too, and yellow was another color option (mine was originally yellow). There is an April 1, 2008 joke page at oldtenspeedgallery.com about a famous bike racing team switching to 1978 lime green Schwinn Sportabouts:

Rock Racing Drop De Rosa For Sportabout

 

[alienator]

That bike isn't anywhere near ugly enough to be a Rock Racing bike. Michael Ball likes to live his lack of taste out loud.

 

[BicyclingGuitar]

That bike isn't anywhere near ugly enough to be a Rock Racing bike. Michael Ball likes to live his lack of taste out loud.

I haven't seen the team, but a while back someone told me in an email that the Rock Racing team apparently has a lot of money behind them as evidenced by their equipment, their clothing, and the impressive graphics on their bikes and their transport vehicles. Apparently they drove up in a bunch of brand-new shiny black Cadillac SUVs (if I'm remembering his email correctly; if not it's my mistake not his). The writer of the email was impressed by them.

Whether or not Ball has lack of taste, this Sportabout story shows he has a good sense of humor! Besides, chacun à son goût.

Oh, back to topic. I was riding yesterday afternoon and found that the gusts of wind were pushing my front wheel around so much it was not safe to play guitar as I rode on a busy street in town doing errands. I grew up next to Travis A.F.B. where the biggest cargo planes in the USAF are based because of the winds there, and I was used to riding in wind with the steel wheels, handlebar and stem my bike used to have. I live in Oregon now and just switched to aluminum wheels, handlebar and stem this year.

I definitely noticed a big difference today from the wind pushing the front wheel around. I could see the wheel turn as a gust of wind hit it, necessitating my stopping playing guitar to grab the handlebars for safety. I guess the difference in weight of all those aluminum parts compared to steel is significant for the front wheel's stability in wind when riding with no hands. I hadn't really noticed much of a difference until yesterday, but it was noticable yesterday. On the good side, there is also a noticable difference in how much easier it is now to go UP hills! My bike is about eight percent lighter than it was before the upgrades.

 

[ecarpet1]

Didn't really know what to title this thread...but I've got a 58cm 5.2 Madone that I put about 350 miles/month on and have owned it for 3 yrs after upgrading from my trusty steelie. Smooth ride but always been curious what part of the bike geometry makes a bike unstable when you sit up/no hands for a break.

This came to light when I rode a Ridley Damocles yesterday and really noticed the difference. I used to be comfortable *bombing* down hills on the steelie with my mitts on the handlebar stem...would never attempt same on Trek. The Ridley brought back that same confidence...very stable. It was also a great deal firmer of a ride and seemed to be much stiffer in the headset area (virtually zero give in the forks under braking...my Trek forks track aft at least 1cm at the tip under braking).

Geometry specs- Trek top tube about an inch longer thus I'm just guessing that this places the center of gravity farther aft and the potential root cause of a less stable platform. Thoughts???

I knew I shouldn't have ridden that Ridely...now I know what I'm missing....

Often the thing we like the most about our new bike--the lively feel---is what we miss the most about our oud bike--the no handed stability. I agree with several of the posters that it could be frame alignment, headset and even rear wheel dish can have an effect.

 

[teamgomez]

Problem solved. Specialized SWorks Tarmac. No more squirrels in the headset

 

[sogood]

has anyone mentioned the headset ? if it is overtighten you get this balance problem

Similar if the saddle is poorly positioned.

I doubt that the geometry is the problem given how big a difference there was per OP's description. After all, track riders ride hands free all the time on track bikes with very sharp geometry.

 

[dhk2]

Problem solved. Specialized SWorks Tarmac. No more squirrels in the headset

That was a simple fix....enjoy the stability of your new ride

 

[rikdee]

Well, let's avoid the whole "rake" debacle for now, as the proper use of "rake" in 2 wheeled industries is all over the map.


Trail is usually what dominates the re-centering force. Trail is the distance between two points:

1. Where an imaginary line drawn along the axis of the head tube hits the ground
2. The center of the tire's contact patch.

On a bike and most every two wheeled machine, the contact patch is behind the intersection of the head tube axis and the ground. Typically on a bike, trail is on the order of 5-6 cm or so, give or take some millimeters here or there. The more trail there is, the greater the re-centering force (all else being equal). Steeper head tube angles generally have shorter trail numbers, all else being equal. However, with bikes, all else isn't equal because of another dimension called fork offset or rake. That's the horizontal distance from the center of the dropouts to the head tube axis. More offset or rake gives less trail, while short offset or rake gives more trail.

Front/rear weight bias can change steering characteristics, but weight bias doesn't usually change dramatically between road bikes.

A very nice, concise capture of trail. I placed it into my cycling file. Thanks!

Rick

 

[keesue]

has anyone mentioned the headset ? if it is overtighten you get this balance problem

Yep, it sure can. Just a wee bit too tight and the steering can get unstable.

 

[alfa011]

Fork geometry first
Wheel base length second

Velociclo