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Downtube folding bike

Old 09-16-09, 04:18 PM
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Neoshlee,

-The stock Kenda tires should be rideable on gravel/unpaved roads, but they're not ideal. If you want to use them anyway, ride them at as low a pressure as you can without pinchflatting.

-On rough surfaces, almost any small-wheeled bike is going to be slower than a similarly equipped full-sized bike. Big wheels are just better at rolling over variations in the surface of the grounds. Fat tires and suspension can do a lot to minimize this difference, however.

-You can put the same sized tires front and rear. This is a pretty "normal" thing to do. It's also common on off-road bikes to put a fatter tire up front. There are a number of reasons for this, which I won't explain here.

-As for buying new tires, a lot depends on what the actual conditions of this "gravel path" are, and whether you want to be switching tires on and off your bike for pavement riding.

-Mountain bike tires are not inherently more flat-resistant than street tires. If you're concerned about flats, you can get belted or otherwise flat-resistant versions of just about every tire out there.

-Choosing a mountain bike tire is primarily about two things: volume and tread. For small wheels, the more volume the better. Get the fattest tire that will fit on your bike. A larger tire can be run at lower pressures, which makes it more comfortable and gives it a larger contact patch (that is, greater traction).

-Tread is a little bit more tricky. The general rule is that the softer, looser and more irregular the surface you're riding, the more aggressive (knobby) your tread should be. However, a really knobby tire is going to be a pain to ride on a paved road. It'll be loud, inefficient, and unpredictable when turning. Riding it on the road a lot will also wear it out quickly. If you get really knobby tires and still want to ride your FS on the road a lot, you may end up deciding to switch between slick and knobby tires regularly.

But here's the thing: knobby treads primarily help you change direction on soft surfaces: accelerate, brake, steer. You can get away with not having knobs on even really gnarly, soft, rocky surfaces if you don't try to brake or steer too hard. So a lot of the question of whether you'll be wanting really knobby tires depends on the nature of these rides your colleagues are doing. Do they ride pretty aggressively, or will it be more of a cruise? If it's a cruise, you can probably get away with some fat slicks. If it's more involved, you'll probably want something knobbier.

Now that all that is said, here's two suggestions:
1. The Schwalbe Big Apple. It's a big fat slick with some flat protection thrown in. I use it on my bike, which primarily sees paved roads but occasionally hits some dirt and gravel. Consensus around here seems to be that it's the best of the fat slick tires. This may just be too slick for you, depending on conditions.

2. The Intense Micro Knobby. This has a lot of little knobs all over the tire. The knobs are small enough that the tire feels decent on the road, but still grips very well on hardpacked dirt and fine gravel. This is a very good on/off road "compromise" tire.
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Old 09-17-09, 01:14 AM
  #1827  
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Originally Posted by alpacalypse

Now that all that is said, here's two suggestions:
1. The Schwalbe Big Apple. It's a big fat slick with some flat protection thrown in. I use it on my bike, which primarily sees paved roads but occasionally hits some dirt and gravel. Consensus around here seems to be that it's the best of the fat slick tires. This may just be too slick for you, depending on conditions.
Thank you so much for the explanation.
I checked out the Schwalbe website and found only 2'' was the smallest Big Apple tires. You mean 2'' tires will fit to the 9FS that has 1.5'' and 1.75'', front and rear?
One more question is how slow the 9FS will be on paved roads with installing the Big Apple tires, compared to the stock tires? Maybe another stupid question..
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Old 09-18-09, 03:07 AM
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Neoshlee,
I'm honestly not sure if the 2" Big Apples will fit the 9FS. They should, but I don't own one so I can't be sure. You can measure the clearance on your frame with a caliper or measuring tape, although you should be aware that tire sizing is an approximate thing. If it turns out that they don't fit, go for the biggest tire you can find that will fit. Primo Comets and Schwalbe Marathons are supposed to be good.

As for whether the Big Apples will slow you down, the answer is still kind of debated, because the tires do several different things. They'll give a bit more rotational weight, which you'll feel slightly while accelerating. But the bike will roll more efficiently because the outer circumference of the tire will be larger, which ups your gearing and also helps your bike roll over imperfections in the road surface. In effect, a big tire makes the wheel act like a slightly bigger wheel.

Ultimately, I personally think that the Big Apples make the bike faster. The main trick here will be finding the right tire pressure. You'll want a pretty low pressure for off road, and a higher pressure on road.
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Old 09-22-09, 07:02 AM
  #1829  
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I'm sharing this picture so it doesn't go to waste:
train.jpg

I took it on the LIRR and it demonstrates that folding a bike completely doesn't always save space nor does a smaller folder (ex I don't think a Brompton would help either).
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Old 09-22-09, 07:04 AM
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Does anyone have advice for locking out the zoom front suspension fork?
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Old 09-22-09, 09:33 AM
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Originally Posted by chucky
I'm sharing this picture so it doesn't go to waste:
Attachment 119342

I took it on the LIRR and it demonstrates that folding a bike completely doesn't always save space nor does a smaller folder (ex I don't think a Brompton would help either).
your orientation is wrong in the picture. what if you put the bike parallel to the seat. that's how i do it in the BART train (california). one time i went inside a bus full of passengers and the only seat available is in front. i sat next to the lady with my dahon mu. mind you, there is also a passenger sitting next in front of me. no problem at all.
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Old 09-22-09, 01:03 PM
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Originally Posted by vmaniqui
your orientation is wrong in the picture. what if you put the bike parallel to the seat. that's how i do it in the BART train (california). one time i went inside a bus full of passengers and the only seat available is in front. i sat next to the lady with my dahon mu. mind you, there is also a passenger sitting next in front of me. no problem at all.
Then nobody would be able to sit on the bench. The bench is rather low so even with everything folded down the bike isn't really short enough to put your legs over it (and neither would be a Brompton). This way I can sit directly behind the bike (to the right in the photo) with my legs diagonally towards the foreground and another passenger can sit on the end of the bench with their back towards me (facing the camera) plus a third passenger can stand to the second passenger's right (left in the photo, foreground to the bike).

Not sure if you're following me, but it works especially since people often have bags and backpacks to fill the seemingly wasted space (I just don't take pictures when it's crowded because then you wouldn't be able to see anything).
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Old 09-23-09, 07:11 AM
  #1833  
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You left your seat partially up and didn't fold your handlebars. When I fold for the Metro, I fold completely. Do you do this to be able to roll your bike, or to unfold more quickly? My 16 inch bike could probably fit under a Metro seat, if I lay it flat. I don't do this, because I use an Ikea blue shopping bag, with part of the bike hanging out of the top.
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Old 09-24-09, 02:21 PM
  #1834  
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Originally Posted by JCFlack
You left your seat partially up and didn't fold your handlebars. When I fold for the Metro, I fold completely. Do you do this to be able to roll your bike, or to unfold more quickly?
Well yeah, but I would fold it completely if it would save any room, but the point is it doesn't: the bike takes up the same amount of space on the train no matter whether it's folded completely or not.
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Old 09-24-09, 03:08 PM
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Are there any good sources for a 1-18" threaded fork for 20" wheel other than downtube.com?

Is this a common size on used kids or bmx bikes?
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Old 12-07-09, 11:43 AM
  #1836  
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Pic Request:
Folded Downtube's w/ road(curved) handlebars. ' just wanna see how much compactness is lost. Thanks in advance!

This forum "upgrade" is not letting me post new thread.
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Old 04-04-10, 08:12 PM
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Can someone explain why some DT's have different sized tires in front and back? I've always wondered this.


Originally Posted by neoshlee
I posted the same question on the downtube website, but would like to repeat here..

I have a 9FS and would like to take it to dirt/gravel trails. I'm not a mountain biker, but just a casual rider who wants to enjoy a little bit of unpaved roads. A few questions I have are
- Are the stock tires (Kenda 1.5 and 1.75) sufficient for the trails? Can I keep up the speed with the colleagues with 26'' mountain bikes?
- Can I put the same size tires (1.75'') for both front and rear?
- Any suggestions for what tires to buy? Just searching Kenda website and buying cheapest mountain bike tires would be suffice?
- Or, just keep the current tires and bring additional tubes/patches?

Thanks!
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Old 05-19-10, 12:50 PM
  #1838  
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Here's my first blush review of the 2009.5 Downtube 8H:

https://utilitycyclist.blogspot.com/2...-commuter.html
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Old 05-20-10, 09:29 AM
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Originally Posted by ShinyBiker
Here's my first blush review of the 2009.5 Downtube 8H:

https://utilitycyclist.blogspot.com/2...-commuter.html
I agree with many of your points. I'm at about 500 miles on my downtube 8H, and had a downtube NS for 3 years (and 3500 miles) previously

1 - Fenders -- I bought the fenders from Xootr (for their Xootr swift), had them on the NS, and moved them to the 8H no problem (had to dremel the metal rods shorter to fit where the screws are on the 8H)

2 - Fork. I like stiff. So far no probs with the zoom, if it breaks I'll swap out the NS fork I saved from the prev. bike

3 - Gearing -- I replaced the front 46T with a 42T; I climb a 315ft vertical hill with one section at 17%, I can do it with this reduction to 42T. Also due to a crash & broken hub I now have the XRF8-W which has more shifting consistency than the original.

4 - Tires -- same thing, I have some 'spare' marathons from my NS that I'll swap in when the Kenda's wear out.
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Old 05-20-10, 07:06 PM
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Jugglerdave,
I did the chainring swap already (!) Also, I've ordered some Planet bike recumbent fenders. Red bike with black fenders should look cool. I'm thinking of adding a chainguard. I keep thinking how slightly faster some marathons would make me. But I'll hold out. I need to post an updated picture when I do all my changes.
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Old 06-16-10, 07:56 PM
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Here are some pictures of my Downtube:

Here's how I fold it most compactly with the handlebars over the rack


Here's how I lock wheels frame and seat with a short length of chain


Here's how I take it on the train


Here's how I balance it with no hands (sorry it almost fell over while I rushed to take the picture)
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Old 06-16-10, 08:03 PM
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nice pics, which parts did you bungee together to get the bike to completely roll like that?
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Old 06-16-10, 09:22 PM
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Originally Posted by hazyphonics
nice pics, which parts did you bungee together to get the bike to completely roll like that?
No bungee. If you set the handlebars at the right angle then the force of rolling naturally makes the front wheel align itself with the rear. Although sometimes I lash the headtube to the seat tube with the strap of my helmet so I don't have to fiddle with the handlebar, I find it's smoother if I steer the front wheel with the bar than when I use the strap.

Don't believe the guff you hear that only certain folders will roll. You can probably roll any folder with a little practice. After all, you didn't learn to ride a bike overnight did you? Here I am rolling my downtube with one hand (actually not even a full hand cause I'm also holding the camera):
video
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Old 06-16-10, 10:29 PM
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thanks chuck! just tried it out and the roll is really smooth. only problem i had was trying to keep the handlebar straight cause the wheel kept hitting the kickstand but itll come with experience. i also stupidly tried to roll the bike back, which caused the pedals and wheels to lock up...
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Old 06-17-10, 07:59 AM
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Originally Posted by hazyphonics
thanks chuck! just tried it out and the roll is really smooth. only problem i had was trying to keep the handlebar straight cause the wheel kept hitting the kickstand but itll come with experience. i also stupidly tried to roll the bike back, which caused the pedals and wheels to lock up...
Try playing with the handlebar riser rotation and/or gripping the bar in a different position. When everything is aligned the wheel shouldn't hit anything unless you push the handlebar sideways to turn.
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Old 06-17-10, 09:28 AM
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we just bought two 8Hs, took them out last weekend and we are very pleased with them.
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Old 09-12-10, 03:54 PM
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Commuting/Panniers/Trunk Bag

I bought a downtube a few years ago and have never been satisfied with my arrangements to carry my stuff. I'd like to get as much as possible off of my back, except for my laptop. First, I bought a downtube trunk bag to fit on the rack. The bag has small panniers built in. Where do I attach the bungee cords that are part of the panniers? Second, are there any more "traditional" panniers that will fit on to the rack of a bike with 20 inch wheels? Third, has anyone attached a crate to the top of the rack? That seems like a great option for my work bag--just put it in the crate instead of unpacking some stuff to go in panniers. Thanks for your help.
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Old 09-12-10, 06:48 PM
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Are Downtube Minis still being made and sold?
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Old 09-12-10, 06:50 PM
  #1849  
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No. Are you looking for one?
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Old 09-12-10, 07:50 PM
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Yes, SesameCrunch. I would be interested in buying one. PM me if you have ideas. Thanks. :-)
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