Diode100

I have to say that chasing ultimate straight line speed on a folding bike seems a bit daft to me, I'm sure if you want to go fast on a bike you can do so for far less money on a fixed frame bike.

fmattheus

Writing such sweeping statements seems a bit daft to me ... there are for example people who don't have space to store a full sized bike. Are they daft for wanting to ride quickly?

Diode100

Hey, where would we be without sweeping statements, life & message boards would be much duller. Folding bikes are a compromise, always, you have to be able to perm any two requirements from three, or you are done for. I know what you mean, i live in a shoe box and have had bikes stolen from outside, so i have a folder which has attributes to enjoy way beyond what speed my puny legs will get it up to. If you want a folder that is inteded to go fast, they are available, you just have to compromise on price and generally folded size. Even, what is possibley the most modded folder, the R20, fast as it can be made to go, is not a folder in the contemporary sense, in that it has a simple hinge in the middle, try lugging that up the stairs and onto the top of the wardrobe. - another compromise to dial in.

Are they daft for wanting to ride quickly ? If it has to be a yes or no answer, then to avoid another sweeping statement, it would have to be no, but in reality if you want to go fast on a folder you have to put speed at or near the top of your essentials list when picking your bike.

itsajustme

Yup. The magic pixie dust is handlepost hinges. In the end all the stuff you mention is really meant to keep the handlebars in a rigid position because apart from the BB (which is still triangulated on most folders) that's where most of the flexing forces are applied.

Dahon has many different handlepost and handlepost hinge designs which make for completely different bikes just as the different handlepost designs differentiate Swifts and Bike Fridays from other makes.

Point taken

Your argument is specious because the paradigm of the bike needing to be built to size is not so applicable to bikes without top tubes or tight wheel clearances. It's like using a belt with a single notch made to length versus one with multiple notches. A multiple notch belt is not "one size", but many sizes manufactured at once just as folders with appropriately sloping seat tubes are not one size but infinitely many sizes. The fit options are not limited, but enhanced.

Finally, the answer to your last question is an unequivocal yes because the infinite number of tries available to the owner guarantees that they will eventually get it perfect as opposed to the LBS who is limited to a few stabs with whatever he's willing to stock. The owner with an adjustable bike gets to "cheat", like taking a multiple choice test over and over until he gets all the answers right which I admit is completely unfair to the LBS.

Bike Friday's frame sizing is a gimmick catering to people who want to emulate what they're accustomed to regardless of whether it's better or worse. They sell one notch belts in multiple lengths to people like yourself who can't wrap their heads around the concept of multiple notches.

Look at the tikit vs Brompton debate. Brompton has already solved many of the "problems" the tikit supposedly addresses, but to a man with a hammer everything looks like a nail and some folks think they need a one notch belt in "their size" just because that's the only way to get a good fit on a nonfolder.

IMHO chasing the ultimate straight line speed seems a bit daft period. Why straight line? It's not going to get you to work any faster (though a bike with good acceleration might) and even if it would shouldn't you be in a streamliner? If you want to ride in a bunch the question is moot because, by definition, then you'll want to ride whatever the others ride.

duke_of_hazard

I am a little offended by this strong negative language describing my bike, which makes it hard for me to believe the rest of what you say. If the D7 is as bad as you claim it to be, then what kind of speeds should I be expecting out of a 'good' folding bike? Is 25-30 mph speeds what the typical 'Urban Utility' rider does? If so, I have yet to cross paths with that person!.

duke_of_hazard

The D7 only has 7 gears, so you feel a big force change when shifting. If you try and spin at the high force you will quickly get tired. Accelerating slooowly is what works for me, or should I be doing something else?

itsajustme

In Baccaigalupe's defense, he did say that "as a general principle, really the best way to improve your performance is via training" and emphasized that ultimately the greatest gains will come from training.

Obviously you're a quick trainer and that's the main reason why you've picked up some techniques so easily and learned to be so fast. I think we can all agree that when it comes down to it a bike is a bike is a bike and the engine is always the most important element. I have no doubt that Lance Armstrong could beat me on a $50 Walmart bike with a flat tire any day.

However, if you don't mind me asking. How can you be so sure about your speeds? I don't use a speedometer myself, but reading the forum I get the impression that perhaps some peoples' speedometers aren't very well tuned, especially if they're considering the "as the crow flies" speed versus the bicycle wiggle. Some food for thought: oscillating a meter left/right per second amounts to an extra 3.6km per hour, which is probably a bigger difference than a Walmart bike and a Cerevelo for you're average rider.

duke_of_hazard

I did calibrate my speedometer by doing a simple rollout of one revolution. I am fairly sure it is accurate +/- 3% . I never oscillate when I ride, just stick to the left most edge of the right tire track patch. But I am curious how oscillating will increase your speed?

AEO

for D7 with 20x1.5" and 11-30 7sp cassette

• gear / GI / difference

1. 52x30 / 33.11 / 25.00%
2. 52x24 / 41.38 / 14.29%
3. 52x21 / 47.30 / 16.67%
4. 52x18 / 55.18 / 20.00%
5. 52x15 / 66.21 / 15.38%
6. 52x13 / 76.40 / 18.18%
7. 52x11 / 90.29 / 0.00%

typically, on a road bike, you want less than 9% jump between gears at the tall end.
even then, you need something like a 60T to get over 100GI.

fmattheus

Just a tip.

Doing a roll out of two or three rotations while sitting on the bike, and then dividing by two or three creates a much more accurate measurement. Much more so than a car speedometer.

itsajustme

Well because if you add the "forward" distance traversed to the "sideways" distance traversed you get a larger overall distance and thus a larger overall speed even though the sideways distance is not useful motion. All bicycles oscillate sideways or else they wouldn't be physically able to stay upright. It's just a matter of how much and, like I said, 1 meter per second (or 50cm deviation from center) equals 3.6km or 2.23 miles per hour which affects even a perfectly calibrated speedometer. I'm not saying you wobble that much, but it's something to consider.

I'm just saying that even if your tire always touches the fog line line the wobble error is probably greater than your measurement error and, together, could be over 6% which is close to the difference between the best and worst bicycles for a well trained rider.

Although, personally I don't see what the point is since speed in mph or kph is not really a useful measurement. Only time over a given route is useful and the route itself will affect that time more than anything else. I guess that that's not very helpful for roadies who only choose the most favorable routes, but it's true.

Bacciagalupe

I'm sorry to tell you that I'm simply stating facts. The D7 is one of the cheapest bikes Dahon makes, and that's mostly due to component choice and limited gearing. It's made for a broad swath of cyclists -- and as such, there is no reason for Dahon to really optimize it for speed.

This is not to say it is a bad bike; clearly it's working for you. It's that there really isn't much you can do to it to make it fast.

In contrast, a bike like the Cervelo S2 is designed from the ground up for pure performance. Everything from the shape of the tubes, to the geometry of the bike, to the carbon fiber layups, to even routing the cables inside the frame, are chosen to reduce aerodynamic drag, increase lateral stiffness, add vertical compliance and improve power transfer. These are not the criteria and decisions you use when designing a general-use, affordable folding bike like the D7.

As to what kind of speeds you'd get with a better bike, I can't quantify it for you, but I can say that a Swift or a 700c road bike will be noticeably faster -- even on a test ride. Or to put it another way: there isn't much about a Swift, BF or 700c entry-level road bike that will slow you down. With the D7, several aspects are designed for general use rather than speed -- e.g. seat tube angle, wheel type, wheel width, tire width and pressure, flexy handlepost, gearing range and gaps between gears, etc etc.

And again, and we probably can't emphasize this enough, the real key is that changing the bike will only do so much for you; training will provide much more significant results, and produces continual improvements over time. Remember, these are bicycles, not motorcycles -- YOU are the engine here. And more power from the engine means more speed....




I hope you won't be shocked when I disagree.

I will heartily say that for many riders, all that's needed is an adequate fit. For example, if you commute 5 miles each way and do the occasional 10-20 mile weekend ride with your better half, then all you need is a fit that doesn't cause injury. For these individuals, a one-size-fits-all approach is perfectly acceptable.

However, the more you ride, the more important fit will become; and if you add performance and/or are doing long rides, it becomes critical.

Different humans have different bodies -- namely, different leg, torso and arm lengths. So if my torso and arms are shorter than yours, you'll need a different reach. Seems pretty basic to me.

It should also be clear that certain specific geometry constraints will impact both aerodynamics and power generation. E.g. a steeper seat tube allows the rider use different muscle groups and generate more power. If the reach is too long, the rider will be too stretched out; too short, and the rider will be cramped. Tolerances can be pretty tight as well -- a 0.5" difference can be enough to make a bike uncomfortable (as I've found from experience).

So let's say you want a bike with a mid-range seat tube angle (for a nice blend of power and riding comfort); a slightly long wheelbase for extra stability and shock absorption; and bars just below the saddle for some aero advantage without straining your back. And you figure out that a specific reach works well for you. Bike Friday? No problem. 700c road bike? You've got lots of models to choose from, and you can swap out the stem, change the bars, change the bar angle, adjust the location of the hoods.... Swift? Pacific Reach? Well, you can adjust the stem, but you're stuck with one seat tube angle and one wheelbase. Dahon? Birdy? Downtube? You're stuck with whatever geometry that bike has (and isn't always published), and in most cases, stem adjustments are minimal or non-existent unless you're willing to sacrifice the fold.

And if you're going to stipulate that the LBS is always incompetent, there's no way they will know which Dahon will meet the characteristics you're looking for.

Or, to put it another way.... Let's say you need a tuxedo, and go to the tux shop. One suit comes in sizes "S, M, L." Another comes in two dozen sizes, e.g. 38 Long, 42 Regular. A third is a custom / bespoke tux. You might get lucky with the Medium -- especially if you only need it for one night and no one's going to pay close attention. But really, which of the 3 types do you think will fit you better...?

If you're a general-use or casual cyclist, one-size-fits-all is fine. If you ride a lot and/or you want to optimize your bicycle for a specific purpose (e.g. long rides or performance), then you will benefit from the ability to select the various geometry and fit options.


... except that if you don't know what you're doing, it's far from a given that even with an unlimited number of tries, you're going to get it right. And if you fall into the category of rider where fit is important, it doesn't help when you can't change a critical parameter like reach.

E.g. I don't have the foggiest idea anymore how to calculate the cosine of an angle. Unless someone teaches me how to do it again, the only way I'm going to get the correct answer is by accident.

I agree that some LBS employees don't know anything about fit, but others are pretty good. YMMV.

AEO

ya, I don't think the fold is compromised enough to matter. it's either a bit fatter or a bit taller.
https://i199.photobucket.com/albums/a...er/folded2.jpg

https://i199.photobucket.com/albums/a...er/folded4.jpg

https://i199.photobucket.com/albums/a...er/folded6.jpg

itsajustme

I agree with everything said here, but then...

Wrong, wrong, and wrong. You are stuck in the nonfolding bike paradigm where the design constraints create different consequences than we see with folding bikes.

First of all, seat tube angle does absolutely not affect power generation because if the relative seat, hand, and pedal positions are the same then the seat tube angle used to achieve it can't possibly affect power generation. Sure, if you build your bike with the seat tube connected directly to the bottom bracket so that you can't change the horizontal seat position without changing the seat tube angle, then yes it will affect power generation, but folders (in particular Dahons) are not designed like that. The seat tube is offset which frees the seat tube angle to define the correct proportions which frame builders and bike fitters would use to portion a fixed frame, except without the welding.

The key idea here is that a folding bike is designed so that one parameter (seat tube length) can be used to specify many (effective seat height, effective reach, effective seat tube angle, etc) to as close of an approximation as you're likely to find in an off-the shelf "permanently sized" frame. Just as a million pixel image of a circle can be specified by just 2 parameters, fitting parameters do not need to all be adjusted independently if the bike is appropriately designed.

I also hate to point out that your notion of 0.5" making a difference is a complete fantasy. It can't be true because between frame flex, saddle choice, muscle growth, and the wage of the LBS employee that fit you there is absolutely no way to achieve 0.5" accuracy and you can give me a referral for your bike fitter if you'd like to prove otherwise.

Even if a nonfolder is like a suit, a belt is not and neither is a folding bike and if you fall into the category of gentleman where fit is important than you're not going to get by without the adjustability of a belt even if you picked the best of three sizes. Don't get me wrong, obviously a completely custom made to measure bike will fit better than an off the shelf one. I just think that, with infinite gradations over a sizeable range, most folders offer a better fit than you can get from a similarly priced nonfolder that comes in S, M, or L. I've never been able to get as good of a fit from a fixed frame as I do for my folders and after this discussion is it not obvious why?

Adjustable size and one-size-fits-all are not the same thing.

stevegor

Sometimes all this technical jargon befuddles my simple brain, all I know is that as an experienced cyclist who loves going very fast...give me a 700c bike, for commuting and touring give me a SWB and for serious MTBing give me a MTB. I can ride with fast bunches on my SWB but the 700c is better, IMHO.
Each bike serves it specific purpose, end of story.

csisfun

Hello,

In your opinion, what is the one part that should be upgraded that gives the biggest improvement in speed on a stock Dahon Speed D7?

itsajustme

A well put and logical conclusion.

JCFlack

Fast? What's fast? I max out at 14-48 with 16" wheels - fast is a foreign concept to me.

duke_of_hazard

For sure the bar ends which lets you be more aerodynamic and cut through the wind at speeds > 15 mph.

Downhillwuss

So did I! and changed the rear wheel and gearing to make faster speeds possible. (Note... I didn't say it made the bike any faster; as some have already said - its the riders physiology and will that makes faster speed happen)

Why wouldn't you want to go fast on a folder? I ride road and MTBs and now this folding thing. I want to go as fast as I can on all of them! The fact that I am fastest on the 700c road bike is a bit irrelevant - I can't go fast on that when I am sat on the folder!

griftereck

some of the smaller SPD clipless pedals come with a clip on plastic platform that makes the pedal bigger for riding with normal shoes.
Small SPD pedals arent much bigger than folded pedals.

I agree with reving out then changing gear. Its bad practice to short shift. Especially on a bike with wide gaps between the gears. As its going to drop your pedaling rate low. And might hurt your knees with the increased pressure on them.

stevegor

If more people persisted when trying drops and they got used to them then they would find out how comfortable and aerodynamic they make a bike.....they make it easier to go faster. A lot of guys here use flatbars with bar ends, but I've found it's not the same, I don't understand the negative views on drops. If you don't like them in an aggressive down position, flip the stem so they angle up. As a lot of guys often ask about increasing the reach in the cockpit, I would have thought drops were the most commonsense answer.
Changing the size of the front ring/s is another easy way to get more speed, that's obvious, but having the strength and fitness to use a bigger ring is other thing.

griftereck

I used to ride racing bikes all the time. I would race in time trials and go touring.

I got a MTB and found it was easier to ride with the more upright position and stronger brakes.
I didnt get such a sore neck and had more confidence in the bike.
But then again. I never rode an MTB for more than 50 miles.

Ive built a couple of road bikes now. My Whirlwind single speed that has upturned drop bars that are cut off. And my 12 speed Raleigh Flyer that has normal drop bars and downtube shifters. I have them with the stems at maximum height. At first I had the bars set so the levers were fairly high. Not to bad an angle though. I was still a bit nervous riding them though. As the brakes dont have the bite of MTB ones. Probably just the old pads that were on the brakes though. Now Ive rotated the bars down a bit. So my arm muscles have a more direct path. Instead of my wrists being twisted. I feel a bit better like this.

It seems sensible that a small wheeled bike would have drop bars. As there narrower than MTB flat bars. Dont need all that leverage on a small wheel. I narrowed the flat bars on my folding bike. Ive only got grips, brake levers and a Sturmey Archer trigger shifter on my bars though.
Though drop bars quite often have a slightly thicker diameter for the handlebar stem. Can be tricky to fit in non road stems

stevegor

It takes time to get used to drops, when starting it just seems wrong, the neck, wrists, shoulders and back may hurt, but that's usually because of a poor set up. Once you strengthen up in those areas it's the most comfortable position there is on a bike IMHO. Oh yes, I've got bikes that have flat bars, and I rode one on a 100 mile ride with a BoB trailer and it killed my wrists, drops rarely do that.

thatsut

hello all,

i commute approx 15 total daily, since the weather started getting nice. there be a slight infestation of the dreaded "fair weather rider" . anyway i ride a brompton normal at 15mph average looking out at the hills enjoying myself listening to bob marley or if im feeling energetic tinto peunte. anyway this morning some guy overtake me.

now im used to being overtake cars, lorries, fighterjet, motorbikes even the faster tractors the slower one i like to race though! !!! but never in 18 months is it by a bicycle. so as i see this young guy pass me on his racing bike. the man part of me (my d**K lol!) said "what are you gonna take that". so i stepped it up a notch pursued him for around 1 mile at 17mph then on the straight part stepped it up to a steady 20 -22mph. dont you just lover the brompton wide range hub. so at the t junction looked back after 3 miles and could bearly see him.

yes yes its stupid. but lots of fun!!!!