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Swift folders

Old 10-11-06, 02:57 PM
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Originally Posted by james_swift
Hey, that's really great you can build your own wheels. Have you thought about building a set of 451 wheels?
I did, but Peter mentioned some issues about brake compatibility in the rear. I know two brakes aren't especially fashionable on a fixed gear, but I live in an area with some very steep hills, and where I'm not comfortable with just one when the conditions are sub par--wet, icy, gravel, etc., especially since I commute a lot at night. One brake is a good as two on dry, smooth asphalt, but I'm not going to see a lot of that over the next 4-5 months.

Plus I knew it would be harder to spec parts for 451. Right now I want to try some wider tires. The current issue of Bicycle Quarterly has some empirical testing showing that, contrary to popular opinion, wider tires have less rolling resistance, all else being equal, and presumably up to a point. The Stelvios are okay, but they're not especially round, and while they're wider than my current 700c tires, I'm curious to trying something in the 1.5 - 1.75 range. I don't recall seeing many offered for the 451 rim size in those widths, but maybe they're out there.

Also, since the 406's are so much closer to a 700c than I expected in terms of ride, I can't help but wonder if I'd be able to tell any difference at all between 406 and 451. All that said, I'm not arguing against 451's, and if Peter hadn't mentioned the rear brake issue, I might have gone in that direction.

As for wheelbuilding--it's not very hard if you read up on what Sheldon Brown and Jobst Brandt have written. They both offer step by step instructions. While I use a nice stand and tensiometer, all you really need is spoke wrench and some patience. You can use any bike frame as a stand.

Jack
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Old 10-14-06, 04:10 PM
  #702  
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No particular reason for this posting other than I enjoyed a lovely ride in the autumn sunshine today (14th October) and thought you might like to share a bit of the experience. The lake is Ullswater in the English Lake District and is just 30 minutes, by car, from my home. The road sign warns motorists to look out for red squirrels - incase the printing is not too clear. I put the Swift in the car and drove to one end of the lake and rode along the water side for the afternoon. Only did about 15 miles but what a ride! Just love the bike.
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Old 10-16-06, 06:06 PM
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What are the odds I can get an old-school friction shifter working with the SRAM derailleur that came on my Swift? I just can't seem to get into the grip shift.
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Old 10-16-06, 10:05 PM
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Originally Posted by zepi
Now I wonder about: what is the difference in the handling of the bike with 406 and 451 wheels?
somewhere in the web I found the following comment:
"20" tires come in 2 flavors. The 451 size is a taller and skinnier version of the BMX (406) size.
Tires and rims are not interchangeable. The 451 size is usually lighter and faster. The wider BMX size is more designed for touring and commuting."
"lighter and faster" is of course exactly what I have in mind and I got a little turned off by the term "touring and commuting". I have my plain gipiemme track bike hubs here, so I still have the choice to pick the size of the rims...
I like the look of the dahon hammerhead that uses 406 wheels. Smaller wheels will also make a smaller fold, right?
I ride alot and would like to avoid sluggish handling. Smaller wheels result in a higher rolling resistance, but my hubs are good track-quality and I hope they will give me some support in that issue.
I would really appreciate some ideas on the topic. Maybe someone tried out the two different rides and will give a little outline on the handling...
Thanks
Z.
As much as rim size will have an effect on handling, tire choice will likely even have a great effect. I personally like the 406 size just for the shear number of tire choices available in this size. Keep in mind that a tire and rim combination that looks fast (tall and skinny) may not be as fast as something like a Big Apple setup especially on rough roads. If you are just wanted to build a track type bike then a 451 with a Stelvios might be the way to go if you are riding on pretty smooth ground.
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Old 10-16-06, 10:06 PM
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Originally Posted by bigbenaugust
What are the odds I can get an old-school friction shifter working with the SRAM derailleur that came on my Swift? I just can't seem to get into the grip shift.
I believe friction shifters will work with pretty much any derailleur. I have an old 70's Raleigh with friction shifters, and I find them quite ok to use - though given the choice I would probably stick with the gripshift. But you could always give it a try, and it should take too long to change back if you changed your mind.

/. Magnus
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Old 10-17-06, 04:55 AM
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Originally Posted by Wavshrdr
As much as rim size will have an effect on handling, tire choice will likely even have a great effect. I personally like the 406 size just for the shear number of tire choices available in this size. Keep in mind that a tire and rim combination that looks fast (tall and skinny) may not be as fast as something like a Big Apple setup especially on rough roads. If you just wanted to build a track type bike then a 451 with a Stelvios might be the way to go if you are riding on pretty smooth ground.
This jibes with my experience: if you want to run narrow, high-pressure tires, you'll generally get better handling with the larger diameter. But you can get even better handling, and comparable (or better!) performance, with a wider tire in the smaller size.

The 50-406 Big Apples are only a few mm smaller in overall diameter than 28-451 Stelvios, but they improve handling and shock absorbtion dramatically.

Try some well-constructed wide tires on your Swift before switching to 451s.
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Old 10-17-06, 08:31 AM
  #707  
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Originally Posted by trentschler
The 50-406 Big Apples are only a few mm smaller in overall diameter than 28-451 Stelvios, but they improve handling and shock absorbtion dramatically....
So how do the Big Apples (20" x 2.0") compare to the Stelvios, and the stock Kenda Kwests, for performance, any idea?
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Old 10-17-06, 10:33 AM
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On glass smooth pavement, the Stelvios are one of the fastest tires your can buy if you run them at high pressures. The ride quality isn't the best. The Big Apples (BA's) may appear to be slow but in reality they are pretty efficient.

A while ago I did roll-down testing between bikes I had with Stelvios and BA's. On a hill with a very smooth bike path, the Stelvios were faster coasting down the hill but not by a huge amount. On another comparable hill and rougher pavement, the BA's had a bigger advantage over the Stelvios than the Stelvios did over the BA's on smooth pavement.

Now for the caveats, the BA's are heavier but they are definitely more flat resistant. I have yet to get a flat on a BA. I have had 5 on Stelvios with less miles. The BA's are heavier so if you are a weight weenie that might matter to you. The BA's ride better than any tire out there that I've tried. They are downright plush and often negate the need for suspension for most folks.

BA's don't look cool to some people. I don't care. The BAs WILL be slower if you can actually push your bike over 20mph as aerodynamically they are less efficicent due to their wider width. If you are one of the elite cyclists who will be consistently riding over 20mph (average) then the BA's will not slice through the wind as efficiently.

I love my BA's and have no put them on almost every bike I can fit them on. I can air them up and eek out a bit more performance or run them at 50psi and have a super plush ride. They work great off road in moderate dirt, sand and grass (not good in mud). I don't mind cutting through a grassy playground as I know I won't knife into soft ground.

If you are building a super light track bike I'd pass but not because of lack of efficiency but if you are the aforementioned weight weenie you'd probably not enjoy the reaction from other bike nerds who don't know the BA's. The BA's are super popular in Europe to the point they design entire bikes (Balloon Bikes) around the wide version of the Big Apples. Their are special Dahons setup with these big fat tires.

I spoke with Stargaze48 extensively before getting him to try a set on his Swift. He was so concerned about many aspects of the tire's performance UNTIL he bought a set. I still have set of Stelvios on a bike but it is sole purpose is maximum speed and ride quality be damned. I do of course carry a tire repair kit with that bike but I gave up doing it on my BA equipped bikes.
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Old 10-17-06, 02:58 PM
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Boy, I'm really tempted to try these. I am convinced that wider does not necessarily mean slower, at least up to a point, so right now I'm mostly concerned that I'll find them too heavy. So now I'm thinking about the Marathon Racer, which is 1.5" in the 406 size. I currently run the folding Stelvios on my Swift. I like them fine enough on pavement, but I occasionally ride gravel, and they are quite poor on loose surfaces, worse even than narrower 700c tires, for reasons probably more related to frame/fork geometry than the tires themselves.

So should I jump all the way up to the 2" BA's, or take the intermediate step of the MR's, and save some weight? One problem is that I ride several different bikes, so it takes me forever to wear out tires, and makes it hard to justify replacing good expensive rubber.

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Old 10-18-06, 01:40 AM
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I loved my BAs and agree with wavshrdr (hi wav) but while in Tucson I got 3 flats in 3 weeks in the rear tire, so I put back the rear Marathon Plus tire. One flat was caused by a large bent nail, no tire could prevent but the 2 other flats were caused by the local thorns. I havn't had a flat in over 3 weeks with the MRs. The front BA hasn't had any yet. When I get to Thailand next month, I may switch back to the rear BA.
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Old 10-18-06, 03:19 AM
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So should I jump all the way up to the 2" BA's, or take the intermediate step of the MR's, and save some weight? One problem is that I ride several different bikes, so it takes me forever to wear out tires, and makes it hard to justify replacing good expensive rubber.
The weight penalty of replacing folding Stelvios with 20 x 2.0 BAs (50/406) is going to be about 320g+ per tyre (+ 50g or so for each of the larger inner tubes). This is a fairly significant weight increase, and it will be immediately noticeable. However, if the road conditions are such that you think they will be beneficial, than BAs are the way forward.

BAs are comfortable and make the bike feel very stable (like tank tracks!) If I were you, I would probably go for a Marathon Slick or Marathon Racer as an interim compromise – more comfortable than a Stelvio and still pretty fast. If they still feel harsh, than a BA may be for you (I know a number of Birdy riders who are swopping sluggish Marathons for the BA in the 50/355 size).

Oh, and if you are going to fit BAs to a fixed Swift, don’t forget that you will now be riding a bike with an extra gear inch or so, and bottom-end acceleration will be particularly affected by the increased rotating mass/size of the wheels – something to think about if you ride in high-density traffic.

I wear out small-wheeled tyres at an alarming rate, so put more miles in, if you want new tyres!

Last edited by Fear&Trembling; 10-20-06 at 09:15 AM.
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Old 10-18-06, 10:25 AM
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Originally Posted by Fear&Trembling
The weight penalty of replacing folding Stelvios with 20 x 2.0 BAs (50/406) is going to be about 320g+ per tyre (+ 50g or so for each of the larger inner tubes).
Wow! I hadn't actually done the math, but adding almost a pound to my 19lb Swift is, as you say, significant.

Originally Posted by Fear&Trembling
I wear out small-wheeled tyres at an alarming rate, so put more miles in, if you want new tyres!
I've only got a couple hundred miles on the Stelvios, so no significant wear, but I also hadn't considered all the extra revolutions per mile. Maybe I'll be able to justify those Marathon Racers sooner than I thought.

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Old 10-18-06, 03:12 PM
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Wow! I hadn't actually done the math, but adding almost a pound to my 19lb Swift is, as you say, significant.
It is (particularly as the extra weight is on the wheels), but the benefits of the BAs may make it worth it.
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Old 10-18-06, 06:28 PM
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Originally Posted by JackJ
Wow! I hadn't actually done the math, but adding almost a pound to my 19lb Swift is, as you say, significant.
How did you get the bike weight that low?
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Old 10-18-06, 07:28 PM
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Originally Posted by Bacciagalupe
How did you get the bike weight that low?
Yeah, my fixed Swift with everything stripped off it just barely tips in at 18.9lbs (digital bathroom scale). JackJ has bigger bars and front and rear brakes, so yeah, 19lbs seems about right.

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Old 10-19-06, 10:59 AM
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Originally Posted by Bacciagalupe
How did you get the bike weight that low?
I weighed it at 19 lbs on my digital bathroom scale, which only has .5 lb resolution. No idea how accurate it is. But 19 lbs was with the stock bars/stem--everything else as shown in the photos. The saddle, pedals, and tires are all much lighter than typical, and the rest comes from no derailleur, no cassette, shorter chain, fewer (and probably lighter) spokes, and probably lighter rims.

I now I'm thinking about adding an extra pound or more in fat tires/tubes. Hmmm....
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Old 10-19-06, 12:13 PM
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FYI - As has been mentioned before, the new steel Swifts have an anticipated delivery of Spring '07.

Approx. weight w/ a Nexus 7 or 8 internal hub is 27 lbs. Pricing will range from $700-$1000 or more depending on how you outfit it.

If you want to email Peter to get on the contact list for when the new steel frames will be available, PM me for his new email address.

And no, I'm not a shill.
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Old 10-19-06, 02:08 PM
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Originally Posted by JackJ
Now I'm thinking about adding an extra pound or more in fat tires/tubes. Hmmm....
True, but what's one pound? One pound won't turn your light bike into a heavy bike! It will still be light, and it will surely be more comfortable.

It depends on your goal(s), of course, and your riding style and environment.

Going from Stelvios to Big Apples will certainly be a change, but I think the width and overall diameter will produce the most noticeable effects, rather than the one additional pound.

And re Big Apples: You might not like 'em! I didn't at first, but I sure do now.
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Old 10-19-06, 05:48 PM
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Originally Posted by JackJ
I now I'm thinking about adding an extra pound or more in fat tires/tubes. Hmmm....
I'd give it some careful thought.

I switched from 20x1.35 Comet Kevlars to the 20x1.50 size, which added 65 grams per wheel. After adjusting my gearing to match the gear inches I had with the smaller tires, I noticed a significant loss in acceleration with the heavier tires. It's a trade-off for a more plush ride to deal with the rough pavement here in SF. I can't imagine adding an extra pound of rotating weight though.

I read somewhere that 1lb of rotating weight is the equivalent of 2lbs on the bike (you can ask the roadie forum).

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Old 10-19-06, 08:32 PM
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Originally Posted by james_swift
I read somewhere that 1lb of rotating weight is the equivalent of 2lbs on the bike (you can ask the roadie forum).
Who needs the roadies?

The energy required to raise a mass M to a speed V is the familiar:

Et=0.5*M*V^2

The energy required to rotate an object with moment of inertia I to a rotaional rate omega is:

Er=0.5*I*omega^2

If the mass M is distributed at the radius R, the the moment of inertia is:

I=M*R^2

For a wheel moving forward at speed V, the rotation rate is:

omega=V/R

so Er=0.5*M*R^2*V^2/R^2=0.5*M*V^2

So a non-rotating mass requires energy

Et=0.5*M*V^2

While a rotating mass requires both the translational energy and the rotational energy to get up to speed.

Et+Er=0.5*M*V^2+0.5*M*V^2 = M*V^2; twice the non-rotating energy.


But, who cares? The energy isn't lost. It's preserved in the angular momentum of the wheel. You might take more time to spin up, but having spun up, the higher angular momentum will give the bike a more stable feel. Unless you are a racer for whom the ability to accerate quickly is critical, I wouldn't fuss overly much about rotating versus non-rotating mass.
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Old 10-20-06, 12:01 AM
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I don't get the weight weenies. Look at the actual change in the total bike and rider weight TOGETHER. A one pound increase on a combined bike and rider weight of 200lbs is NOTHING! You are not spinning these tires up to high rpms so even the energy loss of due to acclerating the extra mass isn't super significant. Keep in mind how much less energy is lost due to the higher efficiency of the BAs if you have rough roads and it isn't funny.

I have crappy roads where I live and the BAs are a treat to ride on and on most courses near my house I am faster on my BAs than my Stelvios. If I lived in Florida it would not be the case but we have a lot of frost damaged roads. I can't ride a Stelvios through grass either and the BAs I easily can.

I used to think (wrongly) that my BAs were a lot slower than my Stelvios because the bike felt a little less snappy. Riding on my test course at an average pace told a different story. My roll-down testing likewise showed that what may feel faster may not actually be. The Stelvios ALWAYS felt faster but that was in part due to the amount of road vibration I felt so they seemed more responsive. Maybe if I had to stop and start every 100 feet then the extra effort to spin up the BAs might almost matter. In the real world I can diet and shave off more weight than the BAs add.

If you are building a track bike, then don't buy the BAs. The vast majority of the people who try them love them. One thing almost all tire companies agree on, higher volume tires are more efficient than lower volume tires when it comes to rolling resistance.

The downside is higher volume normally means adverse impacts on the aerodynamic aspect of the tires. So if you are fast (20mph+) then this might actually matter a little bit when you are up in the speed range where aerodynamic drage becomes the predominant force you must overcome. On my Swift I am not worrying about that too much, on my recumbent it is a different story.
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Old 10-20-06, 04:13 AM
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Unless you are a racer for whom the ability to accerate quickly is critical, I wouldn't fuss overly much about rotating versus non-rotating mass.
However, it is not only racers who need to accelerate quickly – when cycling along congested roads, where the “concertina effect” of traffic is inevitable, the need to accelerate quickly is crucial (well for me anyway). Gaps in the flow of traffic emerge and disappear apace. That said, rider weight/strength/fitness is indubitably far more important than an extra 1lb on your wheels…


You are not spinning these tires up to high rpms so even the energy loss of due to acclerating the extra mass isn't super significant
Jumping from nominal 28/406 to 50/406 makes the circumference of the wheels bigger, not hugely of course, but this also has an effect on acceleration.

Agreed, wind resistance plays a far more important role (above 12mph or so) than issues relating to rotational mass. The key issue with significantly heavier tyres/tubes is the additional weight that you have to lift and carry when the bike is folded...

One thing almost all tire companies agree on, higher volume tires are more efficient than lower volume tires when it comes to rolling resistance.
But at which point do we enter the realm of diminishing returns – 60mm 70mm, 80mm and with which rim/tyre size, on what surface and at what psi? There are so many variables…

I now only use a Stelvio in conjunction with a Pantour suspension hub on one of my folders. I rode with BAs for 2 weeks on my commute and I did not like them. FWIW, I find tyres around the 40mm mark suit my daily requirements in the 20” size (I like Marathon Racers, Primo Comets, Scorchers, Marathon Slicks), but of course, it depends on where and how you cycle. There is no perfect tyre out there; it is all about compromises…

Last edited by Fear&Trembling; 10-20-06 at 08:40 AM.
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Old 10-20-06, 08:58 AM
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Originally Posted by Fear&Trembling
There is no perfect tyre out there; it is all about compromises…
I also suspect that there are differing personal preferences that swamp the other considerations. Many years ago I was talked into riding wider tires on my road bike. When I tried them there was no question that they didn't have the snappy response of the narrower, lighter tires. But they were more comfortable, and with them the bike had a much more stable feel. Of the two effects, the more stable handling is what I enjoy more. I've never gone back.

I imagine that there are people who would describe what I'm feeling as ""sluggish handling" and would hate it.
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Old 10-20-06, 12:44 PM
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I just bookmarked this page in case there's a physics test later.
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Old 10-21-06, 06:48 AM
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All ur bike r belong Enki
 
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I switched-out my Greenspeed Scorchers for my Primo Comets (same size) and thicker tubes last week when it started to rain (although the Scorcher is a nice, light and fast tire, I highly recommend that you DO NOT run them in the rain ). The Comets are 10gm heavier per tire than the Scorchers...not sure how much heavier the tubes are, but let's just say 10gm as well. I haven't noticed a huge loss in acceleration overall, but what is definitely noticeable is the added inertia. I'm riding fixed now, and brake primarily through backpedal force. I can really feel the difference in my legs when beginning my backpedal, to where I'm applying max force coming to a stop, and most definitely when going downhill. After about a dozen intersections, I feel my legs getting shakey in the backpedal, and find myself tapping on my brake a little to compensate. With the lighter Scorchers, I can go brakeless through my entire commute.

I can see now that for fixed riding, the less inertia, the better.
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