My own experience clashes somewhat with the majority view here - my view is that smaller wheels eg 16" does not give a harsher ride than 700c wheels. In fact my experience is to the contrary - big-wheeled bikes I have ridden were harsher over those sharp bumps such as the edge of pavements.
Due to the frequently expressed majority view here, I have begun to waver in my opinion, that perhaps my riding style has imperceptibly changed such that despite smaller wheels' alleged harshness, my style renders the effect of smaller wheels irrelevant. Such a riding style might be to slightly lift myself off the saddle a very small amount on encountering a rising bump, as well as giving the handlebars a small jerk to lift the front wheel over such a bump.
Anyway, I did a mathematical analysis and some simulations of the axle displacement when riding over a square bump, the worst case. The bump I investigated is a square edge 25mm rise and later a fall (opposite sequence of a flat pothole) at a speed of about 20km/h. The findings were very interesting.
I compared a 16" 305x50 wheel with a 700c 622x28 wheel. The 16" 305 wheel is less than half the diameter of the 700c wheel so any effect would be like a worst case. Adding a tyre changes the ratio quite a bit; the 305 wheel got a 50mm tyre (eg Big Apple) and the 700c wheel got a 28mm tyre. So the effective radius of the 16" wheel was 202.5mm and that of the 700c wheel was 339mm.
I looked at the horizontal distance between each axle and the front edge of the bump as the wheel first touches the edge. The ratio between the 2 cases is 1.31 (700c wheel being the largest).
First of all, the result with extremely hard pumped tyres. The vertical acceleration ratio between the 2 cases was also 1.31. Makes sense of course. The 16" wheel suffered the highest vertical acceleration as expected.
Then I dropped the pressure on the 16" wheel by that same ratio, 1.31. So if the 700c wheel was 100psi, the 16" wheel was 76psi. For this, the 2 cases' vertical acceleration amplitude was essentially equal albeit with different shapes. Furthermore, if the pressure of the Big Apple is dropped to say 40psi, the 16" wheel acceleration drops to 60% of the 700c wheel's. The 16" wheel does experience a much bigger rebounce, though, but still very small in the grand scale of things - only about 2mm. Such rebounce would be completely obscured by something like seatpost flex.
So as far as I can see, here is proof: Smaller wheels with everything else being the same, are harsher, but with tyres pumped to realistic pressures, the situation is much the same or even reversed.
:thumb:
jur
05-20-08, 10:58 PM
Here are the 3 cases, 300psi, 75psi and 40psi in that order. For the 1st, both cases had that pressure to establish the base line; for the other 2, the 700c wheel was at 100psi and the 16" wheel as above.
Vertical scale in mm (25V=25mm). Axle1 and accel1 is that of the 16" wheel.
snafu21
05-21-08, 12:58 AM
:bike:
Crikey!
werewolf
05-21-08, 01:43 AM
As a new small wheel (20") rider, I have not found them harsher, but I have found them less stable. Even riding with one hand makes me nervous - forgedabout no hands! That being said, I like 'em!
EvilV
05-21-08, 01:52 AM
Surprising results.
Your point about rising out of the saddle as you spot an upcoming bump is a good one. A long time ago I picked up that tip in Richard's Bicycle Book which I read about 1980. It makes all the difference in the world when hitting a rough patch of tarmac on hard pumped tyres. Richard Ballantyne made the point that by taking your weight on the feet and holding the bars lightly, the bike pivots around the bottom bracket, transmitting much less road shock to your body since your legs act like springs anyway, bending slightly at the knees. I think this riding style puts less strain on the bike itself too rather than sitting out the bumps in the saddle like a sack of potatoes.
werewolf
05-21-08, 02:08 AM
"...Such a riding style might be to slightly lift myself off the saddle a very small amount on encountering a rising bump, as well as giving the handlebars a small jerk to lift the front wheel over such a bump."
That sounds like just an inherent part of riding any bike to me. I thought everybody did that, regardless of wheel size.
EvilV
05-21-08, 05:47 AM
"...Such a riding style might be to slightly lift myself off the saddle a very small amount on encountering a rising bump, as well as giving the handlebars a small jerk to lift the front wheel over such a bump."
That sounds like just an inherent part of riding any bike to me. I thought everybody did that, regardless of wheel size.
ince reading that advice in the Ballantyne book, I have done it on all unsuspended bikes.
makeinu
05-21-08, 06:44 AM
Harsh and noodlely are two sides of the same coin. Notice that for higher pressures although the peak of the acceleration is higher for the smaller wheel, the decay is also much more abrupt.
In other words a larger wheel has more memory. So if you want to control and contain the impact of a series of jolts (for example, by "getting light in the saddle" or "lifting the wheel") the larger wheel will make it more difficult to do so because instead of trying to predict/compensate for each jolt individually you'd need to predict/compensate for them two or three at a time. Also, for an isolated jolt the jolt is "active" for a longer period of time, which again is more difficult to contain/control because it takes more time to contain/control.
More than anything I think this simulation reinforces the fact that larger wheels are a form of suspension like any other.
invisiblehand
05-21-08, 07:55 AM
Excellent work Jur. :thumb:
SesameCrunch
05-21-08, 08:08 AM
Jur, you are indeed the Doctor!
http://deephousepage.com/smilies/respect.gif
vik
05-21-08, 08:32 AM
I rode my Tikit to the next town [25kms] for a meeting recently. I've done this ride many times on a Cannondale road bike with 23mm 700c tires. The 40-349 Greenspeed Scorchers [@ ~50/55psi] on the Tikit completely eliminated the road buzz from rough sections of pavement and even crossing over the rumble strips was considerably less dramatic with the Tikit. I had to look down several times since I wasn't getting the usual feedback from my bike that I had come to expect from these road features.
Foldable Two
05-21-08, 09:03 AM
Nice work, Jur, but it sounds like you've had too much time on your hands since fracturing the folding handle bar on your Downtube Mini.
(Once the replacement part arrives, he won't have time for such "nerdy" analysis. :D )
Simple Simon
05-21-08, 09:07 AM
Nice 1 Jur !!
I think you may be 'preaching to the converted' here tho'
Have you tried cross posting over on Road cycling (http://www.bikeforums.net/forumdisplay.php?f=41) .... they would love to hear this .. I am sure they will give you a nice friendly response :D
cooker
05-21-08, 09:15 AM
If I understand you correctly, you are saying the harsher ride of a small wheel bike can be offset but putting fat squishy tires on it.
The trade off, of course, is rolling resistance. You can soften your ride but it slows you down.
Fat Boy
05-21-08, 09:20 AM
I would say that there is the a couple other issues to look at.
The first would be wheels. Since the smaller wheels generally have more spokes and are all around more stout, there is going to be less wheel defection with a 16" bike as opposed to the 700c. Some 700c wheels are quite flexible. Likewise, the fork and frame of the small bike are both smaller and more sturdy which would tend to transmit more road input to the rider. Generally, we are dealing with a longer seatpost and handlebar post, so that will work in the other direction. I think it would be very difficult to estimate the total road transmissibility without throwing a couple accelerometers on the thing and going for a ride.
My BF with 451 wheels rides nice. The Ti seat boom has a lot to do with it. It rides better than my uber stiff Cannondale TT bike, but not as nicely as my C'dale Six13 road bike. In particular, the front end of the BF bounces around a bit. Since I'm running similar tire pressures on both (Stelvio's on the BF, Mich Pro2Race on the 'Dale) I guess this is to be expected.
Interesting analysis none the less. Great work, Jur.
kb5ql
05-21-08, 10:45 AM
I find this analysis to be utter rubbish. The best ride ever is experienced on an ordinary bicycle (http://en.wikipedia.org/wiki/Penny_farthing).
60" wheels should be the norm for all bikes.
PS -- did I mention that Sturmey-Archer hubs SUCK???
;)
BikeLite
05-21-08, 11:04 AM
kb, maybe ordinary back in the dark ages?
Fat Boy
05-21-08, 11:04 AM
'Boneshaker' just exudes thoughts of a smooth, supple ride, huh?
invisiblehand
05-21-08, 11:55 AM
If I understand you correctly, you are saying the harsher ride of a small wheel bike can be offset but putting fat squishy tires on it.
The trade off, of course, is rolling resistance. You can soften your ride but it slows you down.
I don't have the citations handy -- my apologies -- but I seem to recall that on imperfect surfaces that the increase in rolling resistance due to lower tire pressure is minimal.
Fatter tires, however, are definitely heavier and at the very edge of the wheel. And I would guess that they require fatter rims and fatter tube. Does anyone suppose that there is a meaningful aerodynamic difference?
CaptainSpalding
05-21-08, 03:57 PM
Fatter tires, however, are definitely heavier and at the very edge of the wheel. And I would guess that they require fatter rims and fatter tube. Does anyone suppose that there is a meaningful aerodynamic difference?
Not a meaningful aerodynamic difference, no. But possibly the ride is affected in other ways.
Jur, I assume your analysis and your post were at least partially motivated by our discussion in another thread, here (http://www.bikeforums.net/showthread.php?t=418458). Your analysis is great, and your technical acumen and simulation-fu are definitely superior, but I respectfully submit that the scope may have been too narrow, and misses the big picture.
It seems to me that the dynamics among rider, bike, and road are really, really complex. In your analysis, you model the behavior of wheels and tires on a bike moving on level ground and hitting a square-shaped obstacle head on. You included as variables wheel diameter, tire size, tire pressure, wheelbase, and speed. Your model excluded other variables that may be quite relevant. I suspect that rider/bike weight is a factor. Various profiles of obstacles. The hardness of the obstacle. The incident angle of the tire to the obstacle. Rake/trail/overall geometry. Gyroscopic effect. Weight distribution as affected by an incline. All of these contribute to the perceived comfort of the ride. I would also suggest, for the sake of the integrity of the comparison, that if you are going to choose Big Apples for the 16" wheel (arguably the cushiest tirer available in that size,) you should also do a comparison between the same 16" wheel and a 26" mountain bike rim with a 2.125" dia. tir. Otherwise the conditions of the test tend to skew the data to favor the 16" rim. ;)
It's because of all these variables that, in the thread I referenced, where I generalized, I said that the compromise is between folded size and comfort, rather than wheel size and comfort. I would also add that there are more things that contribute to the perception of overall comfort than just the beating that the wheels, frame, and other components transmit from the road to one's wrists and butt.
Which brings us back to your comment, invisiblehand. It could be that the added weight of the larger tires, owing to gyroscopic effect, mitigates somewhat the twitchiness of the steering, and makes the bike easier to handle over bumps. :)
jur
05-21-08, 05:26 PM
I generally agree with all the comments re the effect of other parts of a bike on the overall ride quality of a given bike. But I was interested in isolating the effect of wheel size and tyre pressure from everything else, to see how much merit there is in the oft-repeated statement that "smaller wheels give a harsher ride". There are other statements which are also dubious, such as certain laced wheels giving harsher rides than others (hooey (http://sheldonbrown.com/gloss_ra-e.html#radial), the amount of vertical compliance is vanishingly small) and certain frame materials giving harsher rides (also hooey (http://www.foldingcyclist.com/folding-bike-frame-metals.html), the geometry and design dominates).
jur
05-21-08, 06:30 PM
I find this analysis to be utter rubbish. The best ride ever is experienced on an ordinary bicycle (http://en.wikipedia.org/wiki/Penny_farthing).
60" wheels should be the norm for all bikes.
PS -- did I mention that Sturmey-Archer hubs SUCK???
;)
The way a wheel rolls over a bump (let's say a blade-like obstacle, up and directly down again) is that the axle locus describes an arc with radius equal to the wheel radius. I didn't realise this before doing the analysis. So the bigger the wheel, the longer drawn out that bump's effect will be. Tyres in the days of the ordinary bicycle were solid, hence the development of the biggest possible wheel that you could handle (that and the gear-inch issue).
Dahon.Steve
05-21-08, 07:03 PM
Surprising results.
Richard Ballantyne made the point that by taking your weight on the feet and holding the bars lightly, the bike pivots around the bottom bracket, transmitting much less road shock to your body since your legs act like springs anyway, bending slightly at the knees. I think this riding style puts less strain on the bike itself too rather than sitting out the bumps in the saddle like a sack of potatoes.
Agreed.
This is the reason why the majority on the forum thinks the smaller wheel is harsher. Ballantyne was talking about what one does on a road bike where the geometry of the rider is not straight up but in a crouch. When the rider is bent over, lifting your weight is easier than if you were sitting straight up like one does on a Brompton. Ritchie to his credit put a rear suspension to make the bike comfortable and it works. Moulton added suspension because he knew the ride was going to be harsh running high pressure tires even though the geometry was similar to a road bike.
Most 16' inch wheel folders have the geometry of either a beach cruiser or comfort hybrid and become quite uncomfortable after an hour of riding. Here's the reason why. After two or three hours, you can't lift your weight straight up for the ruts, bumps and potholes. As a result, you end up hitting all the road abrasions sitting straight up!
Of course, you can get a Brooks Champion Flyer, Thudbuster or suspension seat post to smoothen the ride.
jur
05-22-08, 12:10 AM
I would also suggest, for the sake of the integrity of the comparison, that if you are going to choose Big Apples for the 16" wheel (arguably the cushiest tirer available in that size,) you should also do a comparison between the same 16" wheel and a 26" mountain bike rim with a 2.125" dia. tir. Otherwise the conditions of the test tend to skew the data to favor the 16" rim. ;)
I did this already for a look-see; there was no big difference between the results. Interestingly, when both cases' Big Apples are pumped quite soft, the difference becomes virtually indistinguishable. So a blindfolded chap would not be able to tell which bike was which from a purely wheel feedback POV. (That is to say if he could ride blindfolded in the first place.):injured:
EvilV
05-22-08, 01:07 AM
I find this analysis to be utter rubbish. The best ride ever is experienced on an ordinary bicycle (http://en.wikipedia.org/wiki/Penny_farthing).
60" wheels should be the norm for all bikes.
PS -- did I mention that Sturmey-Archer hubs SUCK???
;)
I prefer my velocipede any day over the ordinary. Here is a sketch 'snapped' by an artist I passed whilst overtaking an overweight rider last week.
This is the reason why the majority on the forum thinks the smaller wheel is harsher. Ballantyne was talking about what one does on a road bike where the geometry of the rider is not straight up but in a crouch. When the rider is bent over, lifting your weight is easier than if you were sitting straight up like one does on a Brompton. Ritchie to his credit put a rear suspension to make the bike comfortable and it works. Moulton added suspension because he knew the ride was going to be harsh running high pressure tires even though the geometry was similar to a road bike.
Most 16' inch wheel folders have the geometry of either a beach cruiser or comfort hybrid and become quite uncomfortable after an hour of riding. Here's the reason why. After two or three hours, you can't lift your weight straight up for the ruts, bumps and potholes. As a result, you end up hitting all the road abrasions sitting straight up!
Of course, you can get a Brooks Champion Flyer, Thudbuster or suspension seat post to smoothen the ride.
Interesting thoughts.
I watched that film of Alex Moulton talking about the development of his small wheeled suspended bikes. He claims that small wheels allow extra efficiencies, but that to really exploit them, he needed high pressure tyres. This meant a harsher ride, hence he developed his suspension systems from ideas used on the motorcycles of old.
Moulton film - worth a look -> http://video.google.com/videoplay?docid=-8522870086389552343&q=moulton
jur
05-22-08, 01:13 AM
I prefer my velocipede anyday over the ordinary. Here is a sketch 'snapped' by an artist I passed of late whilst racing a gig last week.
Yeah - the hovering horse concept will never catch on like the velocipede. Nothing like as practical.
werewolf
05-22-08, 01:49 AM
[QUOTE=EvilV;6739483]I prefer my velocipede any day over the ordinary. Here is a sketch 'snapped' by an artist I passed whilst overtaking an overweight rider last week.
The only reason you passed me is because you caught me by surprise, and I would have soon caught up with you and left you in my dust, but - luckily for you - my hat and powdered wig flew off in the wind, and I had to stop to retrieve them.
badmother
05-22-08, 03:54 AM
Sometimes I prefer the horse. Reason is my energy is limited (due to disease) and I am always afraid of ending up in a situation where I need more energy than i have. Talked with some friends yesterday and said what I often do: Good thing about the horse is if you end up in a nasty situation the horse would get extra energy needed to save its own life, and thereby also mine.
Reason for saying this is I told them about an old friend of mine from when I worked in Zambia. She was 86 at the time, british, daughter of missionaries but educated in UK (doctor) and came back to work in Zam. She wrote a book about herself, her husband and theyr familys. Her husband was much the same. Borned in Africa, educated in UK and back to A to work. Once he came back from UK with a new bike(, must be approx 80 yrs ago). By boat to west africa and then by bike following the Congo river up to the north of Zam. Not sure I would like to do that. Much more wild animals, no roadsigns, sleeping in the bush, maps and so on. That must be "Touring" in it`s right meaning.
Fat Boy
05-22-08, 09:49 AM
There are other statements which are also dubious, such as certain laced wheels giving harsher rides than others (hooey (http://sheldonbrown.com/gloss_ra-e.html#radial), the amount of vertical compliance is vanishingly small) and certain frame materials giving harsher rides (also hooey (http://www.foldingcyclist.com/folding-bike-frame-metals.html), the geometry and design dominates).
Hooey or not, Jur, I promise you that the differences in both wheel stiffness and frame stiffness are quite noticeable by a rider. Isn't it only logical that a 16 spoke wheel would feel different from a 32? And isn't is also logical that a big-tubed aluminum frame could potentially be more stiff than a steel one with a standard tubeset? C'mon now, you've got the background to recognize the many variables at play here.
I like my folders for what they are, but I don't attempt to make them something they're not.
makeinu
05-22-08, 10:48 AM
Hooey or not, Jur, I promise you that the differences in both wheel stiffness and frame stiffness are quite noticeable by a rider. Isn't it only logical that a 16 spoke wheel would feel different from a 32? And isn't is also logical that a big-tubed aluminum frame could potentially be more stiff than a steel one with a standard tubeset? C'mon now, you've got the background to recognize the many variables at play here.
I like my folders for what they are, but I don't attempt to make them something they're not.
I believe Jur's contention is that, different as they may be, things like wheel, frame stiffness, etc can not result in enough physical variation to be important.
My contention, on the other hand, is that small as the physical variation may be, the body is not nearly a linear measuring device. Small physical variations clearly result in large differences in physical sensation in a wide variety of circumstances. The problem with the kinds of physical analysis employed in this thread is that the results must be filtered through the lens of the body.
I for one, am perfectly comfortable riding my 8" wheels over what must be some of the worst potholes in the country. I have a good extra half meter to prepare myself for any hits and another half meter at the end to settle down again, not to mention how much easier it is to control the lighter wheels (while conventional spokes may be good for larger wheels, 3 spoke cast aluminum are clearly a superior choice at 8").
No suspension in the world, whether it be a larger wheel, a spring, or a supple frame, can literally make bumps disappear like the intelligent control of a human being. I am far more comfortable riding the streets around here on 8" wheels than even a car because I hit every pothole with a car and no potholes on my 8"er. As I said before harshness and noodleliness are really two sides of the same coin. Suspension is a fundamentally ham handed approach which, in my opinion, is entirely inappropriate on a vehicle with a dedicated jolt avoidance computer built into its controller.
Not to discount Jur's analysis, but mechanical engineers have a few things yet to learn from video processing engineers when it comes to haptics. While the amplitude of oscillations are easy to understand and analyze, I'm skeptical as to how relevant they really are to actual sensation. One thing that's sure is that that particular flavor of analysis is about 20 years behind the times when it comes to analyzing visual stimuli. That's why all I'm willing to conclude from these results is when it comes to behaving like a conventional suspension, fatter tires (like big apples) can do just as well of a job as larger diameter wheels under appropriately equivalent circumstances (note that "all else being equal" is impossible, for example, spoke count and spoke density can not both remain equal under a change in wheel diameter).
EvilV
05-22-08, 12:37 PM
[quote=EvilV;6739483]I prefer my velocipede any day over the ordinary. Here is a sketch 'snapped' by an artist I passed whilst overtaking an overweight rider last week.
The only reason you passed me is because you caught me by surprise, and I would have soon caught up with you and left you in my dust, but - luckily for you - my hat and powdered wig flew off in the wind, and I had to stop to retrieve them.
LOL - I like your style werewolf.
:)
Actually, I just returned from walking about 105 miles in Spain and carrying my kit. There were many times when I'd have loved to sail down hill on a velocipede just like the ones in the picture. We laugh at these crude machines that are the forerunners of our bikes and understandably so, but they did provide wonderful relief from walking when it came to a downhill stretch. Walking down hill carrying a bag is a pain in the bum.
I felt especially regretful when passed by people on mountain bikes. It just looked so easy by comparison to walking.
Actually, I just returned from walking about 105 miles in Spain and carrying my kit. There were many times when I'd have loved to sail down hill on a velocipede just like the ones in the picture. We laugh at these crude machines that are the forerunners of our bikes and understandably so, but they did provide wonderful relief from walking when it came to a downhill stretch. Walking down hill carrying a bag is a pain in the bum.
I felt especially regretful when passed by people on mountain bikes. It just looked so easy by comparison to walking.
Were you doing the famous Santiago de Compostela pilgrimage?
rhm
05-22-08, 01:03 PM
Before I come to the point, here's a little background on my current situation....
A few days ago, just minutes after I arrived at my office, the rear tire of my Downtube Mini blew out. It was a Primo Comet 16 x 1.35 with less than 500 miles on it. I was pretty glad it didn't blow out in traffic (or worse, on the train!). I think the tire was defective; the hole is in the side wall, apparently unrelated to any other damage. Fortunately the tire tread was not affected, so I patched the tube, applied a liberal amount of duck tape inside the tire as a boot, and rode home at relatively low pressure. Since then, not yet having had time to change the tire, I've resorted to Plan B, which is, at the moment, riding a 1969 Triumph 3-speed to the train station, where I store it in the rented locker where I store the Strida, which I then take onto the train so I can ride it when I get to NYC.
So, anyway, I had very recently been riding only my (16" wheel) Mini; and am now riding my (16" wheel) Strida and my (26 x 1 3/8" wheel) Triumph; and so am in a good position to compare the comfort level of these three bicycles.
Coming to the point, finally: The Triumph, with its steel frame, steel rims, and big wheels, has by far the harshest ride of the three. Aren't steel frames supposed to be supple and lively? Well, both Strida and Mini, with their aluminum frames and small wheels, are more comfortable on the bumps. I notice this mainly in my hands; the Triumph still has its original Brooks mattress saddle, complete with springs.
Agreeing with Makeinu, part of the difference seems to be that the smaller wheels give the Mini and Strida a nimbleness that allows me to avoid bumps on shorter notice than is possible on the Triumph.
Speedo
05-22-08, 02:39 PM
Hooey or not, Jur, I promise you that the differences in both wheel stiffness and frame stiffness are quite noticeable by a rider.
I would agree that this is a true statement.
Isn't it only logical that a 16 spoke wheel would feel different from a 32?
Why? What if the 32 spoke wheel and the 16 spoke wheel were designed to be equally stiff? To quote yourself back to yourself:
C'mon now, you've got the background to recognize the many variables at play here.
And isn't is also logical that a big-tubed aluminum frame could potentially be more stiff than a steel one with a standard tubeset?
Yes, but the fact that it could potentially be doesn't mean that it will always be so. To quote yourself back to yourself:
C'mon now, you've got the background to recognize the many variables at play here.
The devil is in the details. What Jur is saying is that there is there is no (or little) fundamental reason that small wheels should be harsher than big wheels.
Speedo
Fat Boy
05-22-08, 03:56 PM
Why? What if the 32 spoke wheel and the 16 spoke wheel were designed to be equally stiff? To quote yourself back to yourself:
Grow up.
jur
05-22-08, 05:04 PM
Hooey or not, Jur, I promise you that the differences in both wheel stiffness and frame stiffness are quite noticeable by a rider. Isn't it only logical that a 16 spoke wheel would feel different from a 32? And isn't is also logical that a big-tubed aluminum frame could potentially be more stiff than a steel one with a standard tubeset? C'mon now, you've got the background to recognize the many variables at play here.
I like my folders for what they are, but I don't attempt to make them something they're not.Sorry Fat Boy, apparently you misunderstood me. I actually completely agree with you! :)
werewolf
05-22-08, 05:43 PM
[quote=werewolf;6739549]
LOL - I like your style werewolf.
:)
Actually, I just returned from walking about 105 miles in Spain and carrying my kit. There were many times when I'd have loved to sail down hill on a velocipede just like the ones in the picture. We laugh at these crude machines that are the forerunners of our bikes and understandably so, but they did provide wonderful relief from walking when it came to a downhill stretch. Walking down hill carrying a bag is a pain in the bum.
I felt especially regretful when passed by people on mountain bikes. It just looked so easy by comparison to walking.
Thank you, you long-legged velocipede terror of the public byways!
Actually, those things were more than halfway there, I think. They made going downhill fun, and on level ground they were fun too, like scooters, and you just pushed them uphill, and bicycles were never very good going uphill anyway, then or now, ultra low granny gears and all that nonsense notwithstanding.
I was hiking through Holland once, years ago, through the beautiful tulip fields. I don't remember seeing any other hikers in the country. Everybody was either in a motor vehicle or on a bicycle.
East Hill
05-22-08, 06:55 PM
I've done some thread cleanup, and would just like to remind everyone that we are here to ride bicyles :) .
Thanks!
East Hill
Speedo
05-22-08, 08:48 PM
Grow up.
??????
Pretty sensitive. Maybe you shouldn't participate in these discussions if you're so thin skinned.
Speedo
Fat Boy
05-22-08, 09:53 PM
Honestly, dude, what you wrote was pretty ignorant. 1 spoke would feel the same as 32 if it were big enough, wouldn't it? You knew exactly the point I was getting at and were being obtuse. 'Grow up' was a pretty fitting under the circumstances and not overly harsh.
awetmore
05-22-08, 10:09 PM
So as far as I can see, here is proof: Smaller wheels with everything else being the same, are harsher, but with tyres pumped to realistic pressures, the situation is much the same or even reversed.
Everything is not the same when you compare a 50mm tire to a 28mm tire.
alex
awetmore
05-22-08, 10:11 PM
As a new small wheel (20") rider, I have not found them harsher, but I have found them less stable. Even riding with one hand makes me nervous - forgedabout no hands! That being said, I like 'em!
I think that has much more to do with the bike's geometry than the wheel size. I don't think that small wheel geometry is well understood. Many small wheel bicycles just copy the steering geometry (head tube angle and fork offset) from a large wheel bicycle without realizing that trail and wheel flop depend on wheel size.
alex
awetmore
05-22-08, 10:14 PM
The trade off, of course, is rolling resistance. You can soften your ride but it slows you down.
Not always. Tire rolling resistance has much more to do with construction than with the pressure used to inflate them. There are low pressure tires that have lower rolling resistance than very skinny high pressure tires.
Too high of a pressure can increase rolling resistance because the wheel bounces along instead of conforming to the pavement.
We demonstrated both of these in the tire tests in Bicycle Quarterly.
jur
05-22-08, 10:55 PM
Everything is not the same when you compare a 50mm tire to a 28mm tire.
alexIn practical terms yes, but for this which was a purely theoretical exercise, the tires did not have their own part to play except to provide a somewhat damped springiness. I the only parameter which was taken into account was tyre width for determining final wheel radius. But for everything else I assumed that the tires were identical in that they were modeled by an ideal damped spring.
So again, the aim of the exercise was to determine the merit of the general statement, "smaller wheels give a harsher ride", with no parameters other than wheel size and tyre pressure having a say in the matter. Tyre construction and material and frame influences were very deliberately excluded. I even excluded the effect of the square edge digging into the tyre as the wheel first hits the edge.
jur
05-22-08, 11:00 PM
Everything is not the same when you compare a 50mm tire to a 28mm tire.
alexOh yes, and the other thing which I haven't mentioned is that I chose the tyre widths because that is a typical choice for the wheel sizes involved. You would hardly ever put a 50mm tyre on a 700c wheel, or a 28mm tyre on a 16" one. (Well the last one is more common in which case the ride would be harsher, perhaps necessitating suspension a la Moulton.)
awetmore
05-22-08, 11:20 PM
Oh yes, and the other thing which I haven't mentioned is that I chose the tyre widths because that is a typical choice for the wheel sizes involved. You would hardly ever put a 50mm tyre on a 700c wheel, or a 28mm tyre on a 16" one. (Well the last one is more common in which case the ride would be harsher, perhaps necessitating suspension a la Moulton.)
That is true for those two sizes, but it isn't typical that larger wheels use narrower tires. If you were to compare 349 and 590 for instance you'd have been dealing with a normal 35mm (1 3/8") width.
Tire width is important in your test because it sets the minimum lowest pressure to avoid pinch flats.
jur
05-22-08, 11:36 PM
That is true for those two sizes, but it isn't typical that larger wheels use narrower tires. If you were to compare 349 and 590 for instance you'd have been dealing with a normal 35mm (1 3/8") width.
Tire width is important in your test because it sets the minimum lowest pressure to avoid pinch flats.Correct, but even that has been disregarded as each tyre is wide enough to avoid a pinch flat on a 25mm bump.
* goes away, repeats simulation for a humongous 50mm edge with possibility of pinch flats included *
jur
05-23-08, 12:10 AM
Correct, but even that has been disregarded as each tyre is wide enough to avoid a pinch flat on a 25mm bump.
* goes away, repeats simulation for a humongous 50mm edge with possibility of pinch flats included *
Well, I'm not actually sure what I intended to do there... sure at some soft pressures there's pinching... I suppose you could say that you couldn't get 2 fat tyres to have similar responses because the small wheel would get a pinch flat if it was soft enough over a big enough bump where the bigger wheel would make it across without flatting.
But the original purpose of the analysis was to compare an idealised road wheel with an idealised 16" wheel on an idealised surface to evaluate the merit of the harshness statement.