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Old 05-16-07, 09:41 AM   #1
ncscott
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handlebar strength

I just asked about a full size folding bike because of the idea that longer stems are a weak spot. Just how weak the stem on a folding bike with 20 inch wheels? I'm 5' 7-8". Will I be able to crank on the bars like my road bike or will I risk tearing the handlebar off? I'm looking at the downtube bike.
Scott
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Old 05-16-07, 09:54 AM   #2
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In one word. NO. You will have to ride differently
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Old 05-16-07, 10:19 AM   #3
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Quote:
Originally Posted by ncscott
I just asked about a full size folding bike because of the idea that longer stems are a weak spot. Just how weak the stem on a folding bike with 20 inch wheels?
It totally depends on the folding bike you use.

Swift bikes are rock-solid all around; I've never heard any problems with handleposts on Bike Fridays, Giant Halfways either. Unfortunately James Haury is incorrect; use one of these and you can ride normally.

Dahons, on the other hand, have very flexy handleposts. So you shouldn't pull back on the bars at all on those. Not that it would break instantly, but it may well fail at some point in the future.

Not sure about Downtube bikes.
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Old 05-16-07, 10:23 AM   #4
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The handlepost on a downtube is a greater than 2 lb chunk of steel. I would not worry about it at all.
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Old 05-16-07, 12:41 PM   #5
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"The handlepost on a downtube is a greater than 2 lb chunk of steel. I would not worry about it at all."

I read on the Downtube website that they kept it steel for this reason, so it appears that it is less of an issue with the Downtube. Concidering the whole bike is only 24 lbs, that is 2 lbs I can live with. Can any downtube users verify the solidity of the stem/bike joint???
Scott
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Old 05-16-07, 01:03 PM   #6
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Quote:
Originally Posted by ncscott
"The handlepost on a downtube is a greater than 2 lb chunk of steel. I would not worry about it at all."

I read on the Downtube website that they kept it steel for this reason, so it appears that it is less of an issue with the Downtube. Concidering the whole bike is only 24 lbs, that is 2 lbs I can live with. Can any downtube users verify the solidity of the stem/bike joint???
Scott

Except the whole bike is much more than 24 lbs. The weights posted are a bit off.

This downtube weighs 23.5lbs.


Dahon handlepost
forte titanium saddle
FSA crank
XTR rear hub
XT 9 spd cassette
SRAM X9 rear derailluer
SRAM X7 shifter
Forte carbon handlebar
Aluminum stem
nashbar pedals
nashbar isis BB
shorty brake levers
Marathon rear tire

The stock IXNS without rack and fenders around 26lbs actually, maybe more.
The stock downtube stem/handle post is very solid.

Last edited by Loch; 05-16-07 at 01:21 PM.
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Old 05-16-07, 01:23 PM   #7
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So the cadenza is quoted at 27.3, still comparable. Have you noticed a difference between the two handleposts???
So i've heard both sides of the story, yes you can ride it normaly and no you cant, can someone please tell me if a Downtube bike can be riden like a normal bike or will I need to use caution so I do not rip the handlebars off??? I'm not saying I'm abusive, but want a bike that requires no altered riding techniques.
Thanks all
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Old 05-16-07, 02:04 PM   #8
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If you put the cost of a cadenza into a Downtube you would have a much lighter bike for about the same price. So that's a bonus.

You know my view about the Downtube handlepost, it is heavy and rigid you can ride on it like any other bike. The other issue I had with the handlepost, aside from the weight was that the angle made a very cramped riding position. This is why I switched to the dahon post, which is angled forward more. It is more flexy. I'm heavy and ride my bikes hard, and I really don't mind the dahon post, the Downtube post, if the fit is fine would be no issue.

So comparing the two, the dahon fits me better but I ride it a little more carefully, the downtube is stiff like a regular bike, but produces a cramped riding position for me, and adds about 1 lb.



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Old 05-16-07, 04:04 PM   #9
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Quote:
Originally Posted by ncscott
can someone please tell me if a Downtube bike can be riden like a normal bike or will I need to use caution so I do not rip the handlebars off???
Erm, ok, again....

Swift, Bike Friday, Downtube, Giant Halfway, Dahon Cadenza: totally solid handleposts.

Dahon 20" bikes: flimsy handleposts

Savvy?
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Old 05-17-07, 07:05 AM   #10
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Sorry for the urgent tone. When you work second shift and you have nothing to do (check that, nothing you are willing to do) then you get bored and the internet is great. I should have been more specific from the start and asked if a Downtube can be ridden like a normal bike. It appears it can. Which is great for me. Next time I will use only one "?"...
Thanks all,
Scott
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Old 05-17-07, 07:09 AM   #11
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loch,
I just noticed you have two chainrings but no front derailer. Can you fit the front derailer in there? I'm assuming the way you have it set up the other chainring is just keeping space? At the end of my commute I'll be riding up a steep hill, so more gear choices would be usefull.
Scott
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Old 05-17-07, 09:32 AM   #12
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I thought about a front derailluer, but the seat tube size is odd and it would be difficult (probably not impossible but difficult). I have been running the 53/39 setup for awhile on most of my folding bikes. It works very well for me as most of my riding is on the big ring. Occasionally I'll come to a hill that needs the 39T and I shift it with my foot. It works well for me, I toured England and Ireland with a setup like this and really the only drawback is that it takes more time to shift it back up and your finger gets a little dirty.

It's nice to have the option even without the convenience of a frt der.

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Old 05-17-07, 09:55 AM   #13
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Quote:
Originally Posted by Loch
I thought about a front derailluer, but the seat tube size is odd and it would be difficult (probably not impossible but difficult)....
So, mechanically how do you do this? Do you have to change the crank? Add a tensioner?

Edit: And are the Dahon and Downtube handleposts somehow interchangeable?

Last edited by Bacciagalupe; 05-17-07 at 10:29 AM.
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Old 05-17-07, 07:38 PM   #14
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Quote:
Originally Posted by ncscott
Can any downtube users verify the solidity of the stem/bike joint???
Scott
I can vouch for the bars being solid. I'm 187lbs, I ride hard sometimes, pull on uphills. I have all the confidence in the world in it, provided it's not pulled out all the way.
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Old 05-17-07, 09:29 PM   #15
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Quote:
Originally Posted by Bacciagalupe
So, mechanically how do you do this? Do you have to change the crank? Add a tensioner?

Edit: And are the Dahon and Downtube handleposts somehow interchangeable?
Looking at the NS, a front derailluer would be much more difficult, would probably require welding. I considered it longer with my other folders and decided for me it was more trouble than it was worth. Maybe one of these days if I round up some cheap spare parts and some extra time, I'll have a go at it (probably not with the DT, that frame introduces more problems).

Regarding the handlepost; yes on the older dahons they are a quill type handlepost and are interchangeable with the downtube, but they are taller so you don't have as much downward adjustment.
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Old 05-17-07, 09:35 PM   #16
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Loch - your bike's a beauty! All you're missing is a black seatpost and a Batman sticker for the headtube!
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Old 05-17-07, 09:44 PM   #17
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Loch - your bike's a beauty! All you're missing is a black seatpost and a Batman sticker for the headtube!
Thanks, YES and YES, I'd "kill" for a black seatpost!

500mm seatposts are hard to find, maybe I should see how much it would be to get it anodized.
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Old 05-18-07, 07:43 AM   #18
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"Looking at the NS, a front derailluer would be much more difficult, would probably require welding. I considered it longer with my other folders and decided for me it was more trouble than it was worth. Maybe one of these days if I round up some cheap spare parts and some extra time, I'll have a go at it (probably not with the DT, that frame introduces more problems)."

What is the NS???
If you could not fit a derailer in there, have you ever tried using something like a tent stake to help lift the chain without touching it. The only problem with a helper, like the tent stake, would be that it is not attached and capable of being lost.
If fit is an issue then shimano has the e-type front derailers that fit onto the bottom bracket. Unfortunately they are all for mountain bikes and therefor will top out at a 44t big ring. A little bit of fiddling around might fix that? http://www.bikeparts.com/search_resu...p?ID=BPC312320
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Old 05-18-07, 08:06 AM   #19
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Quote:
Originally Posted by Loch
Looking at the NS, a front derailluer would be much more difficult, would probably require welding. I considered it longer with my other folders and decided for me it was more trouble than it was worth. Maybe one of these days if I round up some cheap spare parts and some extra time, I'll have a go at it (probably not with the DT, that frame introduces more problems).
Thanks for the info on the handlepost. I was hoping to swap out the one on my Dahon, but I think it's the newer type.

As to the double front, I was actually asking how you set up the 2nd chainring on a bike that only has one. I can easily think of a few reasons to skip on a front derailleur.
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Old 05-18-07, 08:52 AM   #20
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Quote:
Originally Posted by ncscott
"Looking at the NS, a front derailluer would be much more difficult, would probably require welding. I considered it longer with my other folders and decided for me it was more trouble than it was worth. Maybe one of these days if I round up some cheap spare parts and some extra time, I'll have a go at it (probably not with the DT, that frame introduces more problems)."

What is the NS???
If you could not fit a derailer in there, have you ever tried using something like a tent stake to help lift the chain without touching it. The only problem with a helper, like the tent stake, would be that it is not attached and capable of being lost.
If fit is an issue then shimano has the e-type front derailers that fit onto the bottom bracket. Unfortunately they are all for mountain bikes and therefor will top out at a 44t big ring. A little bit of fiddling around might fix that? http://www.bikeparts.com/search_resu...p?ID=BPC312320
Scott
Sorry, that's the downtube model I have, the IXNS (no suspension).

Yes, some kind of lever you could reach down and shift without touching the chain would be very cool. I've also considered getting a small section of the tubing that they put around the chains of some recumbents so I could grab that instead of the chain (where can I get this stuff?). I really like the lever idea. Somehow stretching an E-type would be an option also, but you'd definately have to figure you out how to increase the chainring capacity, cause 44T isn't going to cut it for a 20 in folder.
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Old 05-18-07, 09:05 AM   #21
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Quote:
Originally Posted by Bacciagalupe
Thanks for the info on the handlepost. I was hoping to swap out the one on my Dahon, but I think it's the newer type.

As to the double front, I was actually asking how you set up the 2nd chainring on a bike that only has one. I can easily think of a few reasons to skip on a front derailleur.
Ah okay, Yes you have to change the crank if it is not set up for a double chainring. Sometimes you need a shorter bottom bracket to get a little better chainline with the big ring (I try to set everthing up to be optimal with the big ring). The rear derailluer handles the tension just fine. A longer cage derailluer would be able to handle an even larger tooth difference in the front, the the SRAM X9 short cage does well with the 53/39. I also don't push it and rarely use the 39T sprocket with the 11&12T sprockets on the rear.

I hope I answered your question that time .

This might be kind of silly, but I just saw this the other day and thought it was interesting. It's a possible way to use a quill type stem with a threadless headset. I don't know how the dahon headsets are setup or if it would even work, but it's a thought.

http://www.calhouncycle.com/productc...&idproduct=138

Last edited by Loch; 05-18-07 at 09:12 AM.
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Old 05-18-07, 10:04 AM   #22
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"This might be kind of silly, but I just saw this the other day and thought it was interesting. It's a possible way to use a quill type stem with a threadless headset. I don't know how the dahon headsets are setup or if it would even work, but it's a thought."

I'm confused why you would want to do that. Most the weight savings in threadless headsets come in removing the quill. It would make adjusting the headset a real pain as well. But since we are on the topic of things that probably wont work, this stem seemed like it had some interesting possiblities. It would make the fold harder but probably be strong and lighter weight.
http://www.calhouncycle.com/productc...&idproduct=978
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Old 05-18-07, 11:27 AM   #23
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Quote:
Originally Posted by Bacciagalupe
It totally depends on the folding bike you use.

Swift bikes are rock-solid all around; I've never heard any problems with handleposts on Bike Fridays, Giant Halfways either. Unfortunately James Haury is incorrect; use one of these and you can ride normally.

Dahons, on the other hand, have very flexy handleposts. So you shouldn't pull back on the bars at all on those. Not that it would break instantly, but it may well fail at some point in the future.

Not sure about Downtube bikes.
I would say fortuneatly I am in error. I have no problem admitting error.
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Old 05-21-07, 08:52 AM   #24
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Quote:
Originally Posted by Loch
I thought about a front derailluer, but the seat tube size is odd and it would be difficult (probably not impossible but difficult). I have been running the 53/39 setup for awhile on most of my folding bikes. It works very well for me as most of my riding is on the big ring. Occasionally I'll come to a hill that needs the 39T and I shift it with my foot. It works well for me, I toured England and Ireland with a setup like this and really the only drawback is that it takes more time to shift it back up and your finger gets a little dirty.

I like the simplicity of this system, Loch. It seems to me that the key to the success of this method, apart from the mechanics of shifting, will be achieving a low enough usable gear on the large chainring and a high enough usable gear on the small chainring that one doesn't need to change from one to the other very often. For my legs, gear inches of 35 and 65 would probably fit the bill. I suspect you are a stronger rider than me. What gears are you running? Also, is the 'foot change' a very delicate process? Can it be done suddenly, when required? Do you ever miss?

P.S. Beautiful looking bike.
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Old 05-21-07, 10:00 AM   #25
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Yes, absolutely, smaller ring in front is definitley for emergency situations and the vast majority of my riding is in the large chainring.

Here is the setup I am running with this bike.
Large ring 53 x Cassette (11-32),estimate gear inches= 96.4, 88.3, 75.7, 66.3, 58.9, 50.5, 44.2, 37.9, 33.1
Small ring 39 x (11-32) gear inches= 70.9, 65, 55.7, 48.8, 43.3, 37.1, 32.5, 27.9, 24.4

The numbers in red would be the non-overlapping gear inches. I try to only use the lowest 3 gears on the cassette with the small ring.

Most of my riding is my commute, it is a 5.5 mile one-way commute that is slightly uphill going to work and downhill coming home. There is one steeper hill that overpasses a highway. For this ride I only use 96.4-66.3.

Where I like the have the option of the extra gears is during recreational rides and going places where I am not familiar with the terrain (I like to use lower gears for non paved bike paths also).

With practice the shift from large ring to small can be very quick and automatic (almost as fast as with a derailluer). I don't recall ever kicking it completely off (it's more of a nudge than a kick). The delicate part comes when shifting back up from small to large, this I usually do by just getting off the bike and putting the chain on the ring. I have done it while moving, but it is a little scary, you have to take your eyes off the road (not good) and align the chain just right or it will fall off the other side.

When we were touring, we used the smaller ring more often. It never was an inconvenience, we always had plenty of time to stop at the top and put the chain back on the big ring. With this type of riding it works very well.
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