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  1. #26
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    The only way to change the stiffness is to replace the seat tube with a thicker or thinner tube. On my Pocket Rocket I use an 11-28 8 speed in the back and a 46-60 in the front. I would agree I that I spend alot of time in the 60. This is a picture of a "Classic Friday". Roger
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  2. #27
    Wheelsuck Fat Boy's Avatar
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    Quote Originally Posted by rhenning View Post
    The only way to change the stiffness is to replace the seat tube with a thicker or thinner tube.
    OK, that makes sense. I thought maybe you could run the seat boom more or less 'engaged' in the chassis. It seemed to me that running it less 'engaged' would be softer, but a little hard on the clamp, so I didn't try it. Changing the whole seat boom is a better way to go about it.

    I think your gearing is probably what I would have done if I was ordering it new. What is your shifter / derailleur setup. I would like to run the same cassette basically the exact same lash-up but 2 teeth taller on the chain ring (since I already have a 62).

  3. #28
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    The shifters are Shimano 8 speed bar-ends and the derailluers are 8 speed Ultegras front and rear. The drivetrain is about mid 1990s amd has worked so well I never saw a reason to change it. The highest gear is 109 gear inches and the lowest is 32 gear inches. I did tweak it a bit when I first got the bike. Changed from a 12-24 cassette to the 11-28. Roger

  4. #29
    Wheelsuck Fat Boy's Avatar
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    After talking with Hugh from BF, I've found out some more info about my bike. It's a late 90's vintage. The shifters are 9 speed 600 (Ultegra). The cassette is an 8 speed cassette, which caused me to scratch my head. It turns out it's actually a 9 speed cassette with the biggest cog left out. That gives it a narrow stack height and the 9 speed spacing, but 1 fewer gear. It also explains the 11-23 8-speed cassette, which isn't supposed to exist. I'm going to get an 11-32 9 speed cassette, ditch the 32 and end up with an 11-28. That will give me 114 gear inches on the top and with a 48 small chainring will give me about 35 on the bottom.

    All in all, it should be a pretty sweet runner after I get done playing with it.

  5. #30
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    When buying the 11-32 make sure that you get a lower level one that doesn't use a spider or carrier for the largest cogs. You'll need to drill out the rivets that holds the cassette together.

    Cheaper SRAM or Shimano cassettes make a good choice.

    Bike Friday did the 8 on 9 thing to get 8 speeds on the 3x7 hubs before the DualDrive came out. I think it's a good solution, it gives you wide range gearing but lets you get wheels with less dish. A 135mm wheel built for a 7sp width freehub is close to dishless.

  6. #31
    Wheelsuck Fat Boy's Avatar
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    OK, I've had 2 somewhat short rides on my Air Friday, so I'm going to do a little bit of a review. I have 2 other bikes that I'm going to compare it with, neither of which is really a good comparison. The first is my Downtube FS IX, the second is my Cannondale road bike.

    1. I gave BF a call and talked to them about my bike. After I gave them the serial number, they were able to tell me about the original owner, and all sorts of stuff about the bike. It's pretty impressive the records they keep. Hugh was the guy I talked to and he had all sorts of advice for me. Keep in mind, I bought the bike used...BF hasn't made of dime off me.....but they will. If you are buying a used Friday, get the serial number and talk to someone at BF about the bike. They'll probably know a lot about it.

    2. My bike is a 1997 model. It has Shimano 600 (Ultegra) components. The bike itself doesn't really look like it has that many miles. Everything feels pretty tight and I don't notice many squeaks or areas of concern. It seems to have been well taken care of. It's pretty amazing that a 10 year old bike has held it's value as well as this one has. I think that is the biggest testament of the BF quality. If you were to buy a $20k car in 1997, it might be worth $5k now. I'd say I paid about 1/2 of what it was originally purchased for. It's held it's value well.

    The 600 shifters take a lot of motion to change gears. I think that's just part of the design, but that's the biggest thing I notice about it compared to my road bike with newer Ultegra components.

    3. I was concerned about the Air Friday seat beam. People talked about the bouncing that you can get into with them. Well, it does exist. At certain cadences, the beam does bounce a little. That cadence is a bit above what I normally ride at (it happens at maybe 110 rpm), so I only hit is when going downhill and I should shift. The beam really smooths out of the road. I road for 45 minutes on Tuesday and Wednesday on an unoccupied car racetrack. No traffic, but it's a little bumpy. That beam really soaks the bumps up. It also seems to soak up the stuff from the front end as well as the rear. Having said that, it doesn't feel like it soaks it up in the same manner that a suspension bike does. It's as smooth as my DT FS over bumps, but it does so in a much more controlled manner. The DT seems to 'pop off' over bumps a lot. This doesn't. I think because the pedaling loads contribute to the problem on the DT.

    I didn't have any big hills to climb, but if I did, I'd guess that there is a fair bit of flex in the handlebar/stem area. It's fine when you're just cruising (even at road bike speeds), but in a sprint or on a steep hill out of the saddle I could see it being an issue. The rear triangle / frame is pretty stinkin' stiff. The actual frame of the bike is pretty solid. In a completely unfair comparison, the DT frame moves around _a lot_ more than this does. I've always felt like my DT frame clamp was pretty solid, but the swingarm is an issue. Like I've said many times, if I were to do it over, I'd have gotten a hardtail DT.

    4. The Downtube folds faster and more completely. It wins this competition hands down. The Air Friday seat beam slides out of the frame after loosening a couple bolts, and then the rear triangle folds around after undoing another bolt. All in all, I had it in my car trunk in about 2 minutes without taking the handlebars off (2 more bolts for the handlbars and a QR for the stem). The DT would have taken 20 seconds and included the handlebar fold. The difference of this is that the Friday is more of a 'packable' bike than a 'folder' that you'd use on a daily basis on a train. They're meant for different uses. The Friday fits better in a suitcase for air travel because it's disassembly is more complete and designed around that criteria. The DT is quicker and more meant to stick in a bag and hide on a metro train. In this they are just different horses for different courses.

    5. The Friday is a fast bike. Forget fast folder, it's a fast bike. I'm not sure if I'm a quite as fast and on my Cannondale, but it's got to be close. The 451 tires roll smoothly and beg to be ridden at full speed. The gearing is good road gearing. I'd be just fine on a group ride with all varieties of high dollar road bikes. I'm one of those that don't believe smaller tires are faster, but I will say that these are about as close as you're going to get to a 700 wheel.

    6. At medium speeds (Maybe, 8-12 mph) the DT is probably the better handling bike. It feels maneuverable, but not twitchy. At that speed, the Friday is twitchy. You're in a road bike posture, with the front having a lot of weight on it. The front feels twitchy compared to the more upright position of the DT. Once you get going, the Friday smooths out nicely. At around 20 mph it's handling is similar to my road bike and the ride is smoother. I think this is a bit of a testament to how well thought out the DT geometry really it. In the range of speed that a DT spends most of it's time, it's a very nice handling bike. When trying to make time on a DT, though, I'd only get to 15-16 mph. On the Friday it's going to be 19-20 for a similar ride.

    7. By having suspension front and rear the DT has some pretenses of being an off-road bike, which it's not. The Friday makes no bones about it. Don't ride me anywhere but on pavement.

    So there you go. That's what I've figured out about my bike so far. I can see upgrading to newer Ultegra shifters and new tires (the old ones are showing minor dry rot). The gearing has already been discussed, but that's about it. Oh ya, and a seat. Right now it has a Bontrager that I don't care for. I'll need a Terry Fly to make me happy.

    So there we go.

  7. #32
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    Fat Boy I think the twitchyness at slow speed comes from the small light wheels. With less centrfugal force than 700c wheels the steering turns much quicker with the same input on the handlebars. As speed increases you get more centifugal force and that feeling goes away. I have let a lot of people try my Pocker Rocket and always warn them that it will be twitchy at first. Most who have ridden it more than 10 miles have agreed with that. They say they do not notice the twitchyness after riding yhay distance. Roger

  8. #33
    jur
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    Quote Originally Posted by rhenning View Post
    Fat Boy I think the twitchyness at slow speed comes from the small light wheels. With less centrfugal force than 700c wheels the steering turns much quicker with the same input on the handlebars. As speed increases you get more centifugal force and that feeling goes away. I have let a lot of people try my Pocker Rocket and always warn them that it will be twitchy at first. Most who have ridden it more than 10 miles have agreed with that. They say they do not notice the twitchyness after riding yhay distance. Roger
    I used to think along those lines too. But I wonder if is not rather the angular moment around the steering axis which determines the twitchiness. Obviously a big wheel has much bigger angular steering moment, so no twitchiness even at slow speeds.

    Reduction of twitchiness at high speed could also be ascribed to the effect of trail. Likewise tiller effect.
    My folding bike photo essays www.dekter.net/

  9. #34
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    Jur in science class did you ever do the experiment of holding spinning bicycle wheels of different sizes by the axles and trying to change the direction of the wheel quickly. It is amazing how much easier it is to do a 20 inch wheel than a 27 inch wheel. Since most bikes people ride have bigger wheels. They naturally get used to pushing with a given amount of force to turn the bike. When I have been riding my 700 wheel bike and then get on my Rocket the same amount of force that would put me in a gentle turn on the 700 bike will cause a sharp turn on the Friday. It just takes a mile or so to get used to it. I will say mine is a little squirely on a fast (35MPH) down hill with a rumbly road. The bike I have is a very early production bike and I have ridden newer ones on the same road and they handle it better. Roger

  10. #35
    Wheelsuck Fat Boy's Avatar
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    I'm sure the small, light wheels are part of the issue. They just don't have much gyroscopic effect. Beyond that, there is some issue of steering geometry. At low speeds, you steer by turning the handlebars. At higher speeds, you turn primarily by leaning. I think that because of the road bike geometry you tend to have a lot of weight forward on the Friday when you're at the 'turn by steering' speeds as opposed to the more upright position of the DT. This coupled with small high pressure tires make for a quick response.

    When you get to the 'turn by leaning' speeds, everything acts fairly similar to any other road bike. It acts plenty quickly, I never tried to ride no-handed, but it seems like it'd be tough to keep in rolling in a straight line.

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