Folding bike and "stability"? Or "track-ability"?
 

Maybe I should ask in the Mechanics subforum but I'll try here first.

My wife and I bought a pair of inexpensive BSO folding bikes from a local big box outlet. They were reeeally cheap so I can't complain about its value.

But a slightly annoying thing is that they don't track very well. I'm not sure if I'm explaining it right but if you don't pay attention, the bike wanders a bit when you ride it. You almost have to constantly make steering corrections to keep it in a straight line. It takes a bit of the enjoyment out of riding it. And for my wife, who isn't that great at bike riding, it's a bit disconcerting.

Is there anything that can be done about it or is that how folding bikes are?

Twitchiness? What's the wheel size?

Wheelsize isn't usually as important as wheel base. Longer bikes feel more stable.

Many of the cheapo folders aren't designed with riding geometry thought through well. Things like rake/trail, weight distribution, wheelbase, etc, all impact the riding qualities of a bike. Smaller wheels can feel less stable too, although with some saddle time and a properly designed bike, that largely goes away. I have no problems riding hands free on my 20" folders.

Its Not how my Brompton or Bike Friday are , a short trail steering @~35mm ala for the B , is not ' twitchy '.

With a front bag load, the ride is even more solid. so load up the front end..?

I expect it's a YGWYPF issue .. :innocent:

don't know those bikes
can you put an aber hallo on it ..
aber hallo is a stem of sorts ... moves the handlebar front .... ie. puts some counterweight on the rotating handlebar
should stop the twitching to a point
thor

Strong disagreement.

By far the biggest impact on steering stability in a bicycle, and indeed in nearly any steered vehicle, is mechanical trail. This is the tendency of the front wheel to want to act like a caster, or put another way, its tendency to resist being steered away from straight. On a bike, various factors impact on mechanical trail, but assuming the steering axis is at a standard angle, the big one is wheel size: small wheels are much more twitchy than big wheels. The other big one, which could be a design flaw in his admittedly crummy bike, might be a high rake, which will also strongly impact on trail.

Wheelbase does have an effect on perceived steering stability but it's nothing close to the effect due to trail.

It's possible that the OP has other problems (headsets etc.) which should be looked at by a competent shop tech. But all other things being equal, yes, the effects he's describing are symptomatic of the kind of bike he bought, and its likely quality.

I agree with Thor an Aber Hallo will help. However, I would try bar ends first. Riders with bar ends hold the handlebar further to the outside, giving more leverage. It helps remove the twitchy feel, and should not hinder the fold as much as the Aber Hallo.

Thanks,
Yan

I'm not disagreeing that trail is more important. My point was that wheel base is more important than wheel size (assuming everything else stays the same).

I'm the OP. I dug up the info on the bike. They are Schwinn Tango 20-inch folding bikes. We got a pair of them for the equivalent of $120 USD each at an end of season clearance a couple of years ago.http://bikeforums.net/attachment.php...hmentid=459298

They do their job and the price was right.

I was just hoping there could be an adjustment made to make them track better. I think the "trail" / "caster" suggestion might have merit. Could one bend the forks to increase this aspect of geometry?

Also, the gearing is way too "low". You can't ride very fast in them without needing to peddle like a Speedy Gonzalez. Could the big cog at the crank be switched out?

Bending the fork straight ? (more rake lowers trail)

Bigger gear ? You will throw away the chainguard too.

SRAM Dual drive rear wheel hub puts a 3 speed IGH in the cassette Hub, so the actual high gear is 25% higher, 4/3rds of the chainring/cog ratio.

the upgrade for each will cost more than Both purchases ..

save Money? Slow Down ! ... What's the Hurry?

I would not sink a single dime into those bikes, I'd ride them just like they are, quirks and all.

Stop looking down over the front wheel.
Ride them more often, say four times a week. I bet you the wiggle fades. If Not, $120 for the pair,,your not In deep.

Trade up..

People often learn too late that when you upgrade a cheap bike, It will still ride like a cheap bike but no longer be cheap..
Ok Ok so what, I was dropped on my head when I was a baby:P

First order test: Ride thru a puddle in as straight a line as possible, then look back at your exit tracks. If the rear track isn't on top of the front track: 1) the frame isn't straight 2) the rear wheel is misaligned and/or 3) either or both the dropouts are canted.

Check the steering bearing for over-tightness. The bars must turn completely free without having play. If the bearings bind a bit, this will ruin the basic balance act of cycling and make you veer all over the place.

Other than that, just keep on going for a few trips at least, if the steering bearing (known as the headset) is set up well, then soon you should get used to the bike handling characteristics and it should cease to be an issue.

I have had a very wide variety of folding bikes; they vary in the steering feel. But I got totally used to all of them.

Along the same lines, make sure the hinge frame clamp is completely closed.

I rode a Dahon Mu model for a month before realizing that the hinge wasn't completely locked in and the frame consequently bent to the left slightly at the joint.

Oddly enough, it still handled just fine and there was no flex at all perceptible while riding.

I would carry more weight on the front wheel instead of the rear. So a pannier or basket in the front rather than the rear should slow down the steering and take advantage of the low trail geometry.

If it's a standard crank then sure, the chainring can be swapped out. But some of the cheaper bikes use nonstandard parts.