Folding Bikes - Wheel Size--How Much Does It Matter?

Some folks (like those at Bike Friday) say size doesn't matter, at least when it comes to wheels. They maintain that their folders perform as well as good road bikes.

In comparing performance of non-folding and folding bikes, what have you noticed with smaller wheels? Is the ride quality good? Is it "twitchy?" Do you need wider tires? Are you more prone to flat tires or other problems?

Thanks!

In terms of "ride quality", as you put it, no difference whatsoever. I ride just as slowly on my old touring bike as on my Bike Friday. Seriously, the only real difference is that the steering feels more precise to me, which I consider an advantage. I can make sharper turns and have better handling in city traffic.

A small wheel bike tends to ride rougher than a large wheeled bike because the small wheels do not bridge gaps and other pavement defects as well as larger wheels.

Folding bikes tend to also be less stable (twitchy) than full size bikes. I suspect that there is typically less trail in the front geometry to keep the folded size at a minumum.

Having ridden a fair few small-wheelers, tyre quality is way more important than wheel size, certainly in the 16-20" range. Good tyres make for a good ride, bad tyres are wallowy and piggish. The stock tyres on non-premium bikes are usually moderately sucky and its a good upgrade.

How it affects super-tiny wheels like the Handybike or Sinclair A-Bike is another matter!

Twitchiness, I think, is down to the difference in spinning momentum between a small wheel and a big one. But you soon adapt to it - I've not ridden a smally that's been unrideably twitchy.

Having ridden a fair few small-wheelers, tyre quality is way more important than wheel size, certainly in the 16-20" range. Good tyres make for a good ride, bad tyres are wallowy and piggish. The stock tyres on non-premium bikes are usually moderately sucky and its a good upgrade.

How it affects super-tiny wheels like the Handybike or Sinclair A-Bike is another matter!

Twitchiness, I think, is down to the difference in spinning momentum between a small wheel and a big one. But you soon adapt to it - I've not ridden a smally that's been unrideably twitchy.


Thanks, Andy,

Do you have any recommendations with regard to good quality tires in the 20-inch size?

I have read good things about schwalbe tires. You may also wish to look up articles by the folding society .I am fairly certain they will have something to say about tires.Check the dahon bike forums also ,U.S not U.K.

I have been very happy with Schwalbe Marathon and Schwalbe City Marathon tires. I've always used the Kevlar versions and have had very few flats.

Thanks, Andy,

Do you have any recommendations with regard to good quality tires in the 20-inch size?

Ian Sims of Greenspeed Trikes has done a lot of testing on 20" and 16" tires. They had an article about his tests in the lastest Velo Vision Magazine.

You can find a thread in the recent trike list archives that includes his discussion of his tests.

http://www.ihpva.org/mailman/listinfo/trikes

He has used Tioga Comp Pools for is 20" trike tires for years as they have a low rolling resistance. Schwalbe Marathons have a poor rolling resistance, but as I and others can attest they are puncture resistant. Ian said that Primo Comets with Kelvar is a pretty good compromise between puncture resistance and low rolling resistance.

BTW Greenspeed has developed a new tire called the Scorcher that I believe has been released in 16" size and they are coming out with a 20". Based on all the research that Greenspeed has done, I will probably give them a try when they come out in a 20" (406mm) size.

http://www.greenspeedrecumbents.com/

I have Schwalbe Marathon slicks on my new Dahon. They seem to roll well but I have too little experience to talk about resistance to flats.

Regards,

Gary
Greenspeed GTO
Dahon Speed 8

How the bike rides is heavily dependent on the frame and fork geometry. It IS possible to design a small wheel bike that is very stable and rides comfortably. But it is also true that most small wheeled bikes on the market do not have very good geometry and tend to have "twitchy" steering.

In terms of overall speed, it's an interesting question. Long-standing speed records were set on Moulton bikes with 18" wheels so there's no question that small wheels can be ridden very quickly. Also, that fastest human powered vehicles on the planet are faired recumbents and the records were mostly set on recumbents with smaller wheels.

Smaller wheels suffer from increased wheel bearing friction but they are more aerodynamic. Smaller wheels, by virtue of being lighter do accelerate faster than larger wheels.

It would be very interesting to do some tests on this subject. My guess is that for people who don't measure performance in seconds, the speed difference between small and large wheels is probably negligible.

I normally cummute in rush hours by small wheel (16" & 20") folders home>train>work, and have always felt the small wheels are a worthwhile compromise - as taking a full sized 26/28" bikes on the train is such a pain (and now banned, in London in rush hours).

But one day this week I was late and did the same route, after rush hour, on a rigid mountainbike (26" road tyres) and I must say (honestly) the ride was much better - more fun ... the difference was instead of subconciously avoiding pot holes and ridges etc. with improved stability, and comfort with less impact from rough bits, I could just concentrate on riding !!! .... going faster and even enjoying kerb hopping. The journey time was the same - the ride was better although the bike took up an embarassing amount of space on the train !

Overall, logic says that although small wheels have some advantages (as previous posts have said), it has to be said that on this forum we are all folder users and so quote these advantages. Especially as we are in a minority and often are in a position to justify our choices.

BUT the truth is ... for riding - big is best.
OK small wheels with high pressures in tyres can perform OK but need either suspension, lower pressures, to give an acceptable ride over normal roads. They also have aerodynamic advantages - but these advantages are at the extremes of use. Under normal riding conditions, where riding routes and comfort are as important as speed, big wheels are better. And the rougher the route, the bigger diameter of wheel the better.
How many 20" wheel or less mountain bikes have you seen ;-)

How the bike rides is heavily dependent on the frame and fork geometry. It IS possible to design a small wheel bike that is very stable and rides comfortably. But it is also true that most small wheeled bikes on the market do not have very good geometry and tend to have "twitchy" steering.

I think that you are right about bike geometry determining "twitchy" or "quick" steering. I went from a Specialized ATB to a Rans Stratus for my first recumbent bike. The Stratus has steering that was the opposite of "quick". It had a 20" front wheel. But, it also had a long wheel base and with the rear wheel well behind the rider. It was very comfortable to ride but almost ponderous in its steering.

Then, went to a Greenspeed trike. The steering was so quick that it almost scared me to death on the first steep downhill, though I understand that Greenspeed has made some steering geometry adjustments to solve this problem now. This quickness or twitchiness of the steering was with the same 20" wheel as on the Stratus. I have since adjusted to steering and have no problem with it.

Having gotten used to the steering on the GTO, I found the steering on the Dahon Speed 8 with 20" wheels to be quite unremarkable. I guess "twitchiness" is in the geometry and in the eye of the beholder.

Regards,

Gary

I ride a 26-inch 2004 Dahon Matrix and a 20-inch 2003 Dahon Vitesse. The Matrix has a more familiar fork and geomety feel and so feels more secure. But my Matrix has a lot of upgrades. So it's like comparing a Doberman to a Boston Terrier ;-)

I think a real test would be to ride a 20-inch Matrix with upgrades comparable to those of the 26-inch Matrix. But since Dahon is probably not going to market a 20-inch Matrix, we may never know ;-)

However, intuitively, I think folder dude has it right. How frame and fork geometry feels -how the interface feels- rules. A Connemara pony is a much different interface (ride) than an Irish hunter ;-)

This afternoon I saw a K2 Zed 20 and before I read this thread, I wondered what it would be like to do some single track on this little beast. It would be fun to compare the ride feel of this kid's scaled-down mountain bike with a comparable K2 26-inch bike to see if it the 20-inch wheels really make a difference. But since most of us are not the incomparable (5'5") Earl Boykins of the Denver Nuggets, we'll never know ;-)

Also of course. if we were to compare the ride of a 26-inch Matrix with the ride of a future 20-inch (scaled down) Matrix, we would have to find a 26-inch equivalent tire to say, a 20 x 1-3/8" Primo Comet.

On second thought, it may not be far fetched for Dahon to introduce a 20-inch version of the current 26-inch Matrix. A 20-inch Matrix (or 20-inch Zero-G) would be much less hassle to travel with and would be a folder that could go everywhere-even on the train in London during rush hour ;-)

:roflmao: :roflmao: