I like this line of reasoning you provided. :) But I don't it really works to cause a messier situation.

I agree that in principle, mud stuck on a 20" wheel is more likely to be flung off a small wheel than a large wheel following this argument.

But (a) once it's flung off, it will be flung off at the linear speed of the wheel (and that will be the same speed regardless of radius) and (2) a wheel will saturate with mud relatively quickly and any new mud that gets on the wheel will come off regardless.

The only other factor that I' haven't already mentioned that I can see making a real difference is if you run the 20" tire at a lower pressure so it has a wider contact patch than the larger tire.

I've ridden larger tires in the rain at lower speeds and been quite covered with mud specks. Fenders are a good thing regardless of tire size.

Cheers,
Charles

To the OP - tomorrow will be a great example of the folder advantage.

Advantage 1 - I'll get up in the morning and if its raining I'll catch the bus just down the street (with the folded bike inside the bus) and get dropped off 2-3 minutes (by folder) from work.
Advantage 2 - After work, I'm meeting up with some friends and I'll simply fold the bike up into the corner of the pub.
Advantage 3 - If I feel like riding home I will, but if not, I'll fold it up and throw it in the back of my friends truck for a ride home.

This would not work with the Vaya.

Linear velocity may be the same, but the angular velocity is higher by however much the difference is in tire circumference. 35% higher in the case of a 20" tire vs. 700c tire.

Yes, I get that.

When you fling mud off of a tire, you aren't really flinging it off of the tire so much as the mud stops sticking to the tire and keeps going whatever direction it was going in*. So it's the linear speed that matters here.

Cheers,
Charles

* When mud flings off of a spinning wheel, it isn't the so-call centrifugal force (which is often called a fictitious force)throwing it off the wheel. Rather, it is the sudden lack of centripedal force that stops acting on the mud and therefore the mud happily moving along how it was (meaning tangentially to the wheel).

We have now turned this thread into a discussion of college-level physics and mathematics :p

yeah, sorry for that. all i know is that, from my experience, an unfendered small wheel folder is considerably messier in the rain than an unfendered full-size bike at equivalent speeds. i do not know all of the science for why that may be. it just is what it is.

but it doesn't much matter because, as has been pointed out multiple times now, fenders are a very wise investment for any bike that's ridden in inclement weather.

Mission accomplished! :D

There is a lot of truth to that and it can be explained with physics. :)

Assuming everything being equal (mainly the friction/adhesion force of the mud on the tire but this is a complicated function of rubber compound, tread design, mud wetness and even mud composition).

Assume the big wheel and the small wheel are traveling with the same linear speed, v, (such as 10 mph).

Mud can only stay on the tire if there is enough centripetal force, which is provided by the friction/adhesion force.

For the same linear speed, the mud on the smaller wheel needs to have a higher centripetal force to stay on because

Centripetal force = m * v^2 / R, where

m is the mass of the mud (same for both big and small wheel),
v is the linear speed (same for both big and small wheel),
R is the radius of the tire (smaller for the small wheel).

So the requirement for the centripetal force is greater for the small wheel, the mud cannot "make the cut" so it flies off along the tangent.

So it is like you have $100 so you can only buy a Wal-Mart blue light special for $88. The LBS $980 deal will fly you off along the tangent. Not everyone will be riding a LBS bike.

This was the same argument that was was presented already. Both the big wheel and the small wheel will quickly become saturated so that any new mud quickly flies off. Once you reach this point, big wheel, small wheel, doesn't make any difference.

Wider/lower pressure tires will fling up more crap because of wider contact area. And folding bikes have the rider closer to the ground and that probably amplifies the effect, too.

This is probably getting somewhat silly. If you're concerned, get fenders. :)

My distance from the ground is determined by the length of my legs and the need for some clearance between the ground and the pedals. I doubt that there's more than an inch difference between my bikes - and I'm not sure if I'm higher or lower on my folder. I pump up my folder tires to slightly higher pressure than in my other bikes, and the tire width is in between that of my road bike and my touring bike.

I haven't noticed much difference in the amount of water/dirt flung from the tires in wet conditions but haven't tried to make any kind of controlled experiment to compare.

I should be more careful about categorically stating there is a difference in height. In general, the bottom bracket is about the height of the wheel hub (although this doesn't have to be true) and your height is (mostly) set relative to the bottom bracket*. So, you will often (but not always) find that folding bikes with 16" or 20" wheels have a lower bottom bracket compared to a bike with 700c or 26" wheels.

Cheers,
Charles

* I set my seat height based on what's comfortable to pedal, and then hope that I can get a foot down. If you set your seat height based off of getting the same amount of foot down regardless of bicycle type, then, yes, you'll be the same height regardless.

I was fitted to my road bike by the LBS shop owner, and then replicated the pedal spindle-to-saddle height on my MTB. The MTB has a higher BB so that means the saddle itself is higher off the ground than on the road bike. Similar thing would happen on a folder with small wheels I would think. If you replicate spindle-to-saddle of other bikes, then the saddle itself will end up lower to the ground. You would also have to be more careful about crank arms or pedals hitting the ground if you pedal through a turn, assuming you use the same crank arm length as on normal bikes.

This is basically what I would expect. I'll also note that folders generally have smaller cranks than full size bikes, so this will affect things as well.

Shorter length crank arms you mean? I was not aware of that. That could mess with things if you're used to a certain fit with a certain crank arm length.

Which is actually kind of funny because a lot of them seem to have a higher BB than usual so you'd be able to use longer cranks and still be able to pedal through corners without running the risk of touching down. Yes I mainly ride a folding bike and prefer it to any of the large wheeled bikes in my stable for commuting or touring.

Concerning rain and road grime in relation to small wheels... we could argue theories all day of whether small wheels or large wheels are 'messier' but my experience has been that, in the conditions I've ridden and at the speeds I ride, I've thrown taller and more voluminous rooster tails and have received larger racing stripes up my back on large wheel bikes than small wheeled bikes... but of course that argument is moot since it's advisable to use fenders anyway. ;)

That would be a big deal for me. I absolutely love standing. Would that be common for all folders?

I wouldn't think so but IMHO that depends on how well the rider can adapt to the feel of a folder. I have been able to stand on all of the folders I've ridden but then I don't see why that's really necessary when the ride isn't for competition and if the bike has a low enough gear to spin.

It's not necessary...I like the workout. :thumb:

Yes Dan, I agree. Back when I started commuting by bike, the Metro didn't have "bike cars" so the folder was necessary, or at least much more appropriate. Now that there are "bike cars" (actually the area is designated for strollers and luggage too), I've been riding my 700Cwheel road bike.

Neither bike has fenders, by the way, so I won't get into the mud slinging that's been going on between the wheel sizes!

Rick / OCRR

Hahaha... nice. :thumb:

Folders tend to have small wheels and upright seating. Their obvious attraction, for some anyway, is their ability to fold for carrying onto mass transit or storing. However, I'm curious, would those of you who ride folders be willing to ride the same bike even if it didn't fold? In other words, is the bike size/shape attractive enough to you to consider it for commuting whether or not it folded (for those of you who don't need it to fold)?

Some people do, because there are in fact bikes out there that have the same form factor and appearance as folding bikes, but do not actually fold up.

Hi,

I agree that many folding bikes are often non-standard sizes and more upright positions (as they come). First, with some modifications, this issue can be greatly ameliorated. Second, some manufactures (Bike Friday, for example) try hard to make bikes that are sized to fit as a regular road bike would.

The folding bike I'm putting together now will fit me almost identically as my regular bike (although right now it is geared higher than my regular bike; I'm trying to fix that now).

For many people commuting, folders make a lot of sense. If it doesn't appeal to you, then don't get one. :)

Cheers,
Charles

Actually, I'm intrigued by them, especially some of those (photographed here) with front and rear racks, they look like great touring bikes. But, if I am to consider one of these, I certainly don't anticipate a need for folding which is why I asked.

No, not for me. I ride the folder because it can fold to a relatively small size (mine has 16" wheels), but if it didn't have the fold feature I would never have purchased it.

Rick / OCRR

people commonly tour them over here because you can bring them on the high speed (330kph/205mph) trains, whereas you can't do that with non-folding bikes.

No. in my opinion a full-size diamond frame bike is across the board superior to the small wheel folder (Dahon Speed P8) that i sometimes ride, with the sole exception that my small wheel folder can fold up real small. that convenience is the sole reason why i own such a bike.

in my opinion: bigger wheels = better ride.

Absolutely. If I could justify the cost, a Moulton TSR9 would be my primary bike. Quite frankly I find large wheels to be cumbersome. If I want to ride a bike with big hoops, I still have my Flying Pigeon PA-02 (635 hoops) for that experience.

+1. Even though my present folders are a one size fits all deal, I have them adjusted to suit my riding style... most notably flat bars set 2" below the top of my Brooks saddle. The Bike Friday that is being built for me at this time will fit me more like my favorite big wheeled road bike which has the same ergo's as my folders aside from a slightly extended reach (2.5") from saddle to bars.

The same applies to bottle generators... the smaller wheel spins faster and so does the dyno.

My new Moulton has very small wheels and a Shimano generator wired to a Halogen lamp... even at low speed the output is exceptional on what is typically used as a higher speed light.

I commute on a Brompton and Spez Tricross. If the Brompton does not fold, I don't think I would ever ride it :-)
The ride quality for me is better on the Tricross. The Brompton shape is OK, but it would not be enough to sway me to get one.