How do Small Wheels Ride? (Part 2)

So, last time we looked at some of the issues that lead to small wheels producing a harsher / less comfortable ride relative to traditional wheel sizes. At the end of the article I promised to look at technological solutions to this problem, and true to word, here we are. The best place to start oddly enough is England in the middle of the 20th century where Sir Alex Moulton, fresh off designing the suspension system for the mini (a car with very tiny wheels) decided to improve upon the diamond frame bicycle. Noting that the bicycle had changed little since the safety frame burst on the scene in the waning years of the 19th century, Moulton concluded that, like all other forms of transportation, the wheel size on bicycles should shrink. However, keenly aware of the issues we looked at last time, he decided that a narrow diameter, high pressure tire, in combination with a suspension system could produce rolling comfort and efficiency in line with standard wheel sizes, while having all the advantage that come with small wheels. His first effort was a huge commercial success and an iconic piece of 1960's Britain: The Moulton F-frame. The front suspension is somewhat obvious, and the second picture is a close-up on the rear suspension, which is basically a block of rubber that the rear triangle / fork can compress. (It is in fact more like a fork if you look closely at it.)


This basic concept is employed by a number of other folding bike manufacturers, perhaps most notably by Brompton. The Brompton design, developed by Andrew Ritchie in 1975 employs the rear suspension block in a rather ingenious fashion -- the entire rear triangle is free to swing under the bike when folding, or compress the rubber block while riding.


The Brompton does not offer any front suspension out side of stem flex, which from my personal experience is minimal. One company though decided that through some clever design and user specific tuning of tube thicknesses that comfort could be achieved through stem and seat tube flex. Enter, Bike Friday:

This particular model, the Air Friday employs a titanium suspension bean in lieu of a more traditional seat tube (as is used on most Bike Fridays) along with the custom "Goose Neck" stem that also provides some forgiveness while riding. Just in case this whole frame flex option seems insufficient to you, there is also the Pantour suspension hub. These special hubs offer up to 1 inch of self contained travel.

They are a popular aftermarket upgrade for Brompton Bicycles and are perhaps most easily found on the Dahon Speed Pro, which ships with a suspension front hub.

Dahon also takes a more simplistic approach to suspension in a number of its folding bikes, notably the Curve series -- larger volume tires. Though some of the rolling efficiency of high pressure, narrow tires is lost (as it would be with any balloon tired cruiser), the added comfort is appreciated. Furthermore, since speed loss is minimal, and these particular bikes are not intended for racing, balloon tires can be a cheap and effective way to overcome some of the drawbacks of small wheels.

In contrast to this approach, Alex Moulton further refined his popular design started in the early 1980's and most recently with the AM New Series. Aside from the obvious lattice work "Space Frame", these bicycles feature a more advanced fluid dampened rear suspension and a parallelogram suspension fork. This design was so impressive as to earn a spot in New York's Museum of Modern Art.

One last approach come from Riese & Muller's Birdy line and is in many ways a modification of the Moulton design. It is notable in that the front parallelogram suspension separates and is actually integral to folding the bicycle.

I hope you enjoyed this tour of the wide variety of suspension mechanisms employed in the small wheeled world. The diversity of design found in small wheeled bicycles and folding bicycles in particular is one of the reasons for my continued interest in the subject, so I hope you found this cursory look enjoyable. Next time, I will look at some of less obvious advantages of small wheeled bicycles and talk a bit about my personal experiences riding them; in the mean time though, get up, and go ride.

How Do Small Wheels Ride? (Part 1)

This is a very important question for many people considering a folding bicycle, or the many other small wheeled options on the market, and it does raise a legitimate challenge for small wheels. Before addressing this though, I should thank Tony Hadland as much of my knowledge of this issue is drawn from his excellent articles and books. Anyway, for a given tire, pressure, load, and road surface, bigger wheels roll more easily. This is due to the fact that a larger wheel will roll over many of the small crack and crevasses in the road that a small wheel will sink into. Due to its' larger rotating mass it also rises and falls more slowly than a smaller wheel. Finally, a small wheel will contact the edge of any hole or bump at a steeper angle than a larger wheel. Envision a monster truck as compared to a regular car:
Or, if you like, check out this graphic I had Pixar whip up to demonstrate my point: Pretty convincing huh? Seriously though, it is an issue. This is actually one of the key reasons that small wheeled mountain bikes don't work particularly well.

Another issue impacting ride comfort is the fact that small wheels are inherently stiffer than larger wheels. This is great sprinting or hill climbing since you don't have to worry about your wheels flexing laterally, but not as great for general riding comfort as it means that the wheel is less compliant vertically, and thus produces a slightly harsher ride quality. (Does this bit remind you of anything you have heard in a bike magazine or shop . . . i.e. "this carbon bike is completely laterally stiff, yet wonderfully vertically compliant -- it produces the perfect ride!!!" Yeah, yeah, yeah, tube shaping and layup techniques have worked some magic in this department, but does it strike anyone else as a bit of an oxymoron to claim that a bike is stiff and compliant? Having worked in the bike industry, I can assure you that most of these claims are just marketing, so don't buy into the hype too much!) Well, enough of that digression . . .

All of the aforementioned issues combined with wood or steel rims and the most primitive of tires led to the modern approximately 28" nominal wheel size. It was the largest wheel size that could be easily accommodated in the diamond frame of the early "Safety" bicycles. However, much as the medieval carts of old have evolved into the Mini Cooper of today . . .


. . . modern technology can adapt to these issues and produce excellent ride quality in a folding/small wheeled bicycle. How? Find out next time, as for now, get up and go ride.

Small Wheels are Slower, Right?

Hey, loyal readers! Sorry to disappoint all six of you with the 4 day layoff, but it was a busy weekend of . . . well, nothing. Stuff went down, etc. . . in the future you can expect at least 3 posts a week, sometimes as many as 5 though, so . . . you got that going for you. Anyway, on to the question of the day: Are Small Wheels Slower? This presumption is a common misconception, with some basis in fact, but probably not for the reasons many would expect. The most common point was addressed last time -- different gearing ratios allow small wheels to propel you at the same speed as larger wheels. Beyond this issue, we have to flip back to the physics that govern how a wheel functions. (Before delving into this I'd like to thank Bike Friday, Alex Moulton, and Tony Hadland for contributing to my own knowledge of these issues. I'll summarize what I gleaned from them in this post.)

I'll kick off with some of the more easily understood advantages. 1) Smaller wheels weigh less; 2) they present a smaller frontal area, and thus less aerodynamic drag; 3) the shorter spokes also produce less turbulence as they rotate -- turbulence equates to aerodynamic drag, thus smaller wheel are doubly better in this case. (You can even use disc wheels or some sort of cover for the spokes to further alleviate this issue as in a time trial bike with a much lower destabilizing effect from crosswind)


Ok, so those 3 points are pretty easy to grasp; the next issue relates to inertia and involves both positives and negatives for small wheeled bicycles. When you accelerate from a stop on a bicycle, the vast majority of your energy goes towards putting the mass of your body and your bicycle into forward motion. In the case of the wheels, you are not just moving their mass in the direction you are traveling, but setting the whole mass spinning as well. The lower overall mass of small wheels means this is an easier task, but you also benefit from the fact that the mass is closer to the axle of the wheel.

Imagine opening a door. Normally, the knob is placed far away from the hinges (the fulcrum) and it requires relatively little force to open. Now imagine closing the same door, but instead of pushing near the knob, you apply force very close to the hinge . . . it will be incredibly difficult. The same concept applies to bicycle wheels -- a case in which you are always driving forward momentum by applying a force near the fulcrum point (the rear hub). Thus the larger the wheel, and consequently the further away the rim and tire are from the center of the hub, the more force you will have to impart to start the wheel rotating. (I think that may have been the most simplified explanation of torque and the physics of levers and wheels in all of human history; for a more detailed discussion go here, or here, or check out this book.) The end result of all of this is that is is easier to accelerate a bicycle with smaller wheels. This by the way is not just a hypothetical difference, it is noticeably easier. The converse though is that at speed, you have a smaller flywheel effect from the mass of the wheels tendency to remain rotating. This means that after speeding down a hill on your small wheeled bike, you will experience a little less momentum carrying you up the next hill. I cannot say I have personally noticed this to the same extent I notice quicker acceleration at low speeds, but science says that it is there.

I am sure you as you read all this, you are thinking "That physics stuff is great, and I conceptually understand these effects, but what concrete numbers can I apply to actually riding?" Thankfully someone else wondered the same thing and the end result is that the smaller rotating mass of small wheels is more efficient below 16 mph, and the greater gyroscopic effect of a larger wheel is beneficial above 33mph; between the two speeds the difference is minimal. I am sure that we all think of ourselves as speed demons, but how often do you really go above 33 mph? Not that often right? (If you disagree, then you are deluded -- the record speed in an individual time trial in the Tour de France is a 34.27 mph average over a 4.47 mile course). So in the case of normal riding, small wheels will either benefit you or be no different from regular wheels speed wise. If you live in a city and commute like my self, smaller wheels are especially nice because you are constantly stopping and starting with the flow of traffic.

If you are still skeptical, keep in mind that virtually all human powered vehicle speed records are set with small wheels. Check out the International Human Powered Vehicle Association (IHPVA) for further info.

Varna Diablo II - the fastest human powered vehicle on earth at 81 mph

Moulton Liner II - The fastest upright bicycle in the world since 1986 (51.29 mph)

All in all, I think that should answer any doubts about the speed of small wheels. Next time we look at the ride quality / comfort of small wheels and folding bikes. As for now, get up and go ride.

Don't I Have to Pedal More?

For many people, this is the very first question they will ask when encountering a small wheeled folding bicycle. (I will discuss folding bicycles with normal wheels in the future) I have heard this query more times than I can count, and it is often followed by " . . . really? . . . like you can go up hills and everything?!?" -- and I can assure you that yes, I can go up hills with my folding bicycle. in fact, I can bike at the same speed as a normal bicycle in any situation.

This miracle is brought to you through the amazing simple machine that is gearing. So, if you have smaller wheels, you can compensate by either using larger chainrings, or smaller cogs on the cassette / freewheel / hub gear. Shimano even makes a group specifically for this purpose called Capreo, and despite the need for some new tools to install and remove (a completely uncommon issue in the bike industry), it works really well. In general though, special equipment is entirely unnecessary because most of us bike in the middle range of our bicycle's gearing most of the time. Smaller wheels and standard gearing just mean that you use a higher gear that you normally would to ride at a given speed. Sure you lose that 110 inch top gear, but you may gain some nice lower end gearing to plod up hills (especially nice for commuting). For you roadies out there, this is basically the same concept as a compact crankset, which as you may have noticed is all the rage these days. In all reality, a small percentage of bicycle riders need or even use the highest few gearing combinations they have (53-11 much?). Given this fact, you would be much better served by a lower range with narrower jumps between gears. In fact this will even offer greater efficiency as you have more gears to chose from while riding the speeds you normally ride at, and it also encourages you to ride smoothly at a higher cadence in a lower gear as opposed to stomping on the pedals and wasting energy.

So, to answer the question, no, you don't have to pedal more with smaller wheels. You may not have the same high end gearing available to you as on a traditional road bike, but you can if it is that important to you! However, when you actually take the time to think through how you bike and what you want to use your bike for, I think you may realize that the lower gearing easily offered on a folding bike with standard parts will be a more functional set up. Many of the benefits of folding bicycles come down to this point of functionality; and as with many aspects of life, functional utility is the most important factor driving long term usage and enjoyment of a product.

Sure that Colnago Presidente looks AWESOME hanging in the bike store's window. Fortunately, it will also look awesome hanging on your wall when you try to pass it off as an artistic tribute to modern industrial design while explaining why you don't ride it 6 months after purchase.

Tune in next time for "Aren't Small Wheels Slower?", as for now, get up and go ride.

Why You Should Want a Folding Bike

If you bike frequently, or even just live in a major city, I suspect that you have at some point encountered a folding bicycle. (The fact that you have found your way to this blog also supports this theory, but then again, you may just have time on your hands and I am not one to judge.) I am also willing to bet that you had one of three reactions this first time you saw a folding bike:

1) That . . . is . . . the coolest thing . . . I have ever seen . . . I . . . must have one. (If this is you, then you may not need to read this post)

2) What the hell is that, and why doesn't this strange person have a normal bicycle? Don't they have to pedal more? I should probably keep an eye on them as they may do something else crazy.

3) Ughhhh . . . why is someone bringing a hunk of metal into this store/on the subway/etc? Can't they just drive a car or lock it outside like everyone else?

This is for those of you that fall into the last two categories as well as those of you that have some interest in a folding bike or other alternative forms of transportation, but still have questions and concerns about their practicality. For the time being, I won't go into the modicum of benefits of bicycling and especially of using the bicycle as a means of transportation -- suffice it to say that many of us weigh more than we want to, probably drive a lot and spend a lot of time sitting in traffic, and at least a few of us have concerns about the long term environmental impact of carbon fueled vehicles. Riding a bicycle contributes to resolving all of these issues.

Why not a regular bicycle? Well, in many cases, why not. Personally, I would generally prefer to ride a full size, non-folding bicycle in most situations. The inherent suspension of larger wheels offers a more comfortable ride, the lack on hinges for folding offer a lower weight, and in many cases also offer a more rigid frame, and frankly, a full size bicycle just looks . . . well, better to most eyes.

Case in Point:



However, the reality of the situation is that in a lot of cases, a traditional bicycle is far from ideal. Lets consider a few of them:

1) Travel - whether you are flying halfway across the globe, or taking a short trip upstate, traditional bicycles are inherently bulky and difficult to travel with. If you want to fly you first have to either get a cardboard bike box from a store or spend hundreds of dollars on a case, neither of which will guarantee the safety of what for many people is a substantial investment. Then you have to get this giant box to the airport where you will likely have to pay between $80 and $100 each way for the privilege of lugging it on the plane; or you can pay $40 to hundreds of dollars each way to ship your box where you are going. Also, don't forget that you will have to a) find somewhere to ship it to, b) send it days ahead of time, and c) arrange to pick it up somehow once you have arrived. Sounds like fun, right.

As for driving, you are faced with getting an expensive roof mounted rack, an awkward trunk or hitch mounted model, or fold down the rear seats and jam the bike in the trunk. When you get to your destination, you now likely have the pleasure of riding a wet bike (rain), covered in bugs, and with much of the grease blown out of its seals, or you get to clean the blackest grease you can imagine off your automobile's luxurious interior. Oh, and don't forget that the bikes you strapped to your car eliminated the wind tunnel testing done in the last century and effectively made your car the aerodynamic equivalent of the Beverly Hillbillies sweet ride.



2) Storage - This is an especially important consideration for people that live in cities (like myself) where space is often at a premium It never feels good to know that your bicycle is taking up $200 rental space in your 500 sq. ft. apartment.



3) Theft Prevention - Like it or not, bicycle theft is a HUGE issue in many areas. As much fun as it is to ride your $5000 carbon steed, the 40lbs of locks needed to sort of secure it seem to negate most of the weight savings of that full Record groupo. Most people therefore end up with either an absolute piece of crap salvage job, or some sort of low end bicycle and the 40lbs of locks, with the knowledge that the bike will still inevitably be stolen or vandalized some day. Hopefully, that happens just as the bike has started to fall apart from being left outside all the time, and the fact that it was a lousy bike to begin with.

************** SOLUTION - FOLDING BICYCLES **************

As I discussed earlier, folding bikes are not ideal in all situations, and they certainly have drawbacks relative to traditional cycles; they do however resolve issues that for many people make owning and riding a bike all but impossible. We'll discuss the drawbacks in a later post, but let's look at the folding bicycle in relation to each of the three issues mentioned above.

1) Travel - Many companies, Bike Friday is perhaps the best known, offer cycles that can be easily packed into a regulation sized suitcase. That means no giant bike box, no trip to the bike shop to get your bike taken apart and reassembled, no added fees at the airport or need to ship days ahead of your trip. As for weekend jaunts or trips with the car, a folding bike easily fits into a trunk (you can actually fit quite a few if you are traveling with a group). An additional benefit of this ease of transport is the ability to use multi modal transport. For many trips, especially for many who want to commute to work, the distance is to great as to be practical with a bicycle. However, there may be public transportation, be it a bus, train, ferry, etc. within a few miles of home and work. With a folding bike, you can easily ride to the train, get on without enduring the aggravation of other passengers at bringing a full size bike on during rush hour, and then get off and ride your bike the rest of the way to work having cut much of the distance out of the trip. As population has decentralized, this situation is an increasingly common one, and many people don't even realize that options outside of driving even exist.



2) Storage - This seems almost self obvious. Most folding bikes easily fit in a closet, behind a couch, or even on larger shelving units.


3) Theft Prevention - In many ways the same situation as storage -- folding bikes are easy to bring into essentially anywhere you may want to go (work, stores, restaurants, movie theaters, etc.) In places like my native NYC, theft is a preposterously large issue for would be cyclists to surmount. The peace of mind that comes from knowing that you're bike is in no danger of being stolen or vandalized is incredibly liberating. It allows you a great deal of flexibility in the type of trip you would make by bicycle, from going to dinner, to getting groceries, to seeing a movie at a theater miles from where you live.

***************** CONCLUSIONS *****************

Folding bikes may not be right for you, but I strongly encourage you to think more seriously about them before immediately dismissing them as many people do. They offer a number of benefits, especially to the city dweller, and can be an excellent compromise for many people unsatisfied with some of the drawbacks of a traditional bicycle (even you crazy recumbent riders out there -- folding recumbents do exist!)

In the next post I plan to look at the many unfounded criticisms of folding bikes (as well as some valid ones). From there we will see where this grows too. I hope to look at the wide variety of folding bikes available today and offer some of my thoughts on their individual merits. You can also expect periodic news and reviews of new products along with general thoughts on cycling outside of the folding world. Ultimately, I'd love to bring you interviews with some of the important players in the folding bike world, but I suspect that may be a ways off. Hopefully, you will enjoy the ride as I figure it all out.

Why is this happenning?!?!

In my own attempt to explore folding bicycles I found that information tends to be difficult to find and most of it seems to be brought to you by the English. While this allowed for a charming presentation and many quaint turns of phrase, it unfortunately still made it a challenge to find the information you wanted. This blog will hopefully make it easier on those of you with an interest in folding bikes and provide a resource both for those with years of experience and those just beginning the journey.

Welcome!

So . . . here we are a blog . . . presumably relating to bicycles. I have worked with bikes for quite a while, and got interested in folding bikes a few years ago as an interesting and useful, albeit really quirky subset of the cycling world. I found it more challenging than it perhaps should be to find info on what is out there, and I aim to correct that as best I can with this blog. You can expect my opinions and thoughts on folding bike related subjects, general thoughts on bicycles at times, links to things I found interesting, and lastly whatever other random musings I feel like recording for all the world to not read. I can't really say how frequent postings will be as of right now, but I can promise that over the long term this will hopefully be a good resource for those of you getting interested in folding bicycle . . . as for the rest of you, it will inevitably provide plenty of material to mock and make snarky comments about -- which as we all know is the only real reason for having a blog. Enjoy!