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Old 06-11-08, 12:41 PM   #1
Silverexpress
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Dahon - A potential SAFETY ISSUE - Handlebar Twisting

After putting 250 miles on my new Dahon Vitesse, I've come upon an issue which I think affects the riders safety.

It has to do with the handlebar extension twisting. It seems as though the clamp used is not strong enough to withstand the counteracting moments between the handlebar and the front wheel.

In doing research on the net, I've discovered that this is a normal occurrance with this design. It's been reported happening on other models that use this Dahon extending handlebar assembly - called the "Radius Telescope Handlepost" that uses "X-twist technology". According to Dahon's website:

http://www.dahon.com/technology/component.htm

The method of using a groove and a screw on the backside of the quick release clamp prevents the handlebar from twisting. However, I've found that there is still enough play to cause a mis-alignment. There has been no reported injuries....yet on the internet. On my bike the handlebars go out of alignment gradually, but it goes out every time no matter how tight I make that quick release.

Since this Dahon Radius Telescope Handlepost has been out since 2005, has anyone found a fix? I really like my Dahon so far, except for what I think is a potential safety issue.

Here is the lastest thread on this very same issue on the Dahon Forums!

http://www.dahon.com/forum/index.php...t=0#entry38905

Last edited by Silverexpress; 06-11-08 at 12:51 PM.
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Old 06-11-08, 01:26 PM   #2
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I've never experienced an issue like this even with older dahons that have had out-dated handlepost systems.

Most of my bikes I don't ride with the bars as high as yours, so you might be putting more leverage on it.

But I do ride a curve SL with the handlepost at full extension and my old speed pro was pretty high up when I wanted to fold it quickly.

Unless you have a defective part the key is in the adjustment. You need to make sure the post is oil and grease free, if I needed to I might even ruff up the surface finish if it seemed too slick (you can purchase anti slip compound for added grip, although I've never needed it), adjust the quick release so that you can barely move the handlebars by hand and it will not move during riding. Like the old quill stems you could always move them if you forced them, but they wouldn't move while riding.

This is a folding bike and there will a little flex in the handlepost and handlebar, but it shouldn't be slipping.

I do NOT in anyway think it is a SAFETY ISSUE.
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Old 06-11-08, 01:37 PM   #3
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that clamp just doesn't do the job. i experience the same twisting on mine as well.
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Old 06-11-08, 03:08 PM   #4
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safe or not, it's an issue. I should not be fixing a bike I just bought for $700. Adjusting maybe, demanding a part that was missing from the packaging - a stretch, but sanding down a finish, applying anti slip compound...etc... goes beyond what I expect for $700.

I will sand down the black anodizing, and apply anti-slip compound. This will cost me time, gas, and money that could've gone towards upgrades, and riding time.
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Old 06-11-08, 03:53 PM   #5
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Where do you get anti-slip compound? What's the brand name?
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Old 06-11-08, 04:02 PM   #6
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Maybe this will point you in the right direction....



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Old 06-11-08, 04:15 PM   #7
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i also face such a problem..what i did was to take out the screw at the collar of joint, drill through the handle post..use a tool to set some screw threads..lastly replace the existing screw with a longer screw..it won't move anymore..

make sure you align the handle post before you drill..but if the handle post is slight off after the drilling, you can adjust the position by loosening the headset (i mean the piece of metal that you need a 10mm allen key to open)..
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Old 06-11-08, 05:01 PM   #8
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I don't think roughing up the surface of the stem is going beyond what I would expect, but that's me (even though I haven't even had to do that).

I have had to do it on various other bikes and parts that ended up having slightly slicker finish that what the designer specified.

Unless there is something wrong with the part, I do not see any other needed solution.

Here is an example of the the anti-slip compound I was refering to if you really feel it is required (It's called liquid torque and there are various other brands).

http://ritcheylogic.com/web/Ritchey~...3858&live=true
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Old 06-11-08, 05:18 PM   #9
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Quote:
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Here is an example of the the anti-slip compound I was refering to if you really feel it is required (It's called liquid torque and there are various other brands).

http://ritcheylogic.com/web/Ritchey~...3858&live=true
Tacx makes a product called Dynamic Compound that is similar.
FSA makes a carbon paste that is the same idea.

Unless Dahon's production is slipping recently (no pun intended), the handlepost should not twist under normal circumstances. I've never had a need to do anything special for either of our 2006 models.

PS. I would not drill the handlepost for any reason.
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Old 06-11-08, 07:20 PM   #10
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Threads like this will no doubt help bring the issue to the attention of a starving lawyer with time on his/her hands who will initiate some class action that will result in a sudden increase in the spending power of the lawyer and a more expensive folding bike for the rest of us. No worries.

Last edited by sotto; 06-11-08 at 08:21 PM.
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Old 06-11-08, 07:26 PM   #11
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I went out and bought 80 grit sandpaper (black type), and contact cleaner ( works great). Took awhile to sand most of the black anodizing off. It is a very slippery coating, and I have a feeling this is the primary contributing factor. I sanded it off from the male post and from the inside of the female portion. When I get back home, I will go over it with my Dremel and a steel brush wheel again.

It is more solid now. However I still plan on doing the following...

1. Try the anti slip compound
2. Swap out the original clamp with a wider clamp

I'll ride it tomorrow to the LBS and I'll report back my findings, and also I'll let Dahon know about what was happening, what I did, and what I think is the primary cause. Maybe they'll correct it somehow for future builds.

Time spent including getting the sand paper, cleaner, and looking for anti-slip compound to sanding, and reassembling...4 hrs.

Besides all this, I still like the bike alot. It affords me the ability to bike on business trips - resulting in maintained good health and outlook (just in case my boss happens to read this). As before, I like the looks, the internal hub, and the overall build quality.

Has anyone experienced this with the silver Radius Telescope Handlepost. Is it bare aluminum or is it anodized also?

Last edited by Silverexpress; 06-11-08 at 08:06 PM.
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Old 06-11-08, 09:22 PM   #12
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they are all anodized otherwise they would oxidise and hundredthousands of folks would cry bloody murder that there shiny new bicycle looked blootchy and not as they expected ....

After a while this ( the too loose handlebarstem) will go away as most of us learn to spin faster and dont pull on the handlebars like on a regular bike....hardcore folks can replace the adjustable handlepost with a non adjustable version, like on the speed tr and MU sl and other models .....

Remember that if we hear from 5 or 6 folks here its not necessary the same for 296597 others ( and thats last year only ) Althouh I am sure Dahon will look into it , as they have with most other complaints



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Old 06-11-08, 10:30 PM   #13
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Thor,

Is there an insert that I might be missing? I noticed that there is one on the seat tube.
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Old 06-12-08, 07:45 AM   #14
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Quote:
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they are all anodized otherwise they would oxidise and hundredthousands of folks would cry bloody murder that there shiny new bicycle looked blootchy and not as they expected ....

After a while this ( the too loose handlebarstem) will go away as most of us learn to spin faster and dont pull on the handlebars like on a regular bike....hardcore folks can replace the adjustable handlepost with a non adjustable version, like on the speed tr and MU sl and other models .....

Remember that if we hear from 5 or 6 folks here its not necessary the same for 296597 others ( and thats last year only ) Althouh I am sure Dahon will look into it , as they have with most other complaints



thor
i experience the problem mostly when i'm switching gears on the twist shifter.
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Old 06-12-08, 08:48 AM   #15
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dahon has actually increased the diameter of the handle post to address to this problem..but seems like it doesn't help..
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Old 06-12-08, 09:06 AM   #16
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I've logged my 200th mile on my Vitesse this week and have been having the same problem. It hasn't felt like a safety issue yet, but it's certainly annoying.
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Old 06-12-08, 10:11 AM   #17
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Thor,

Is there an insert that I might be missing? I noticed that there is one on the seat tube.
No, there is no insert/shim for the handlepost.

If you want to use an extra clamp on the adjustable handlepost, a 31.8/32.0 seatpost clamp can fit at the top part of the lower-handlepost section. (It will not fit lower down, since with most clamps, they have a lip at the top that normally keeps them in place on the top of your seatpost tube... unless you file that lip off, or find one without such a lip.) In this way you can fit an additional clamp on there. The normal Dahon handlepost clamp is about 1 inch down the lower-section. I have actually removed by Dahon clamp altogether in favour of a 3rd party clamp, though I would not recommend this unless you are counting grams.

I am using an Extralite 31.8 clamp at the moment, although a better choice might be the Salsa clamps (32.0) as it is a more robust clamp and I felt it fit more securely.
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Old 06-12-08, 10:14 AM   #18
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Just bought a second hand Dahon Helios P8 (http://www.bikefold.com/dahon_helio_p8_bike.htm) last night. Paid CAD $240 which I thought was a fair. Overall, very impressed with the components (Truvativ, Kinetix wheels, Schwalbe Marathons, Ritchey bar, Biologic grips & seat, SRAM 3.0 Comp shifters. Planet Bike rear fender. The bike accelerates very well and its handling is just superb. I adapted to the bike right away and it felt completely natural.

However, the handlebar post is loose!! What is the matter with Dahon? They have known about this issue a long time. Being the largest manufacturer of folders, it is not difficult for them to redesign this part and make it work. In all other aspects, I think this Dahon is a fine, fine bike.
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Old 06-12-08, 10:44 AM   #19
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Slipping handlebar clamp

I have cured this problem on my Curve SL by filing two flats on the nut (at opposite end of the QR clamp), so that I can tighten the clamp (if necessary) in the closed position with a spanner.
Also agree that the parts must be clean and particularly grease free if effective clamping is to be achievd.
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Old 06-12-08, 11:39 AM   #20
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What is the matter with Dahon?
I'm waiting on my third Matrix frame (second warranty replacement). If you get an answer to this, I'd love to know it.
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Old 06-12-08, 01:43 PM   #21
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Compare the seatpost QR to the handlepost extension QR, and you will see a variation on mechanical advantage. While the slot is about the same length allowing a 'squeeze zone', the seatpost QR is placed at the extreme top affording maximum 'crush'. Oddly, the handlepost QR is centered in the slot, requiring more force to exert the same hold.

I'll bet that moving the screw hole / QR position up about a quarter inch would go a long way towards clamping it sufficiently to prevent unwanted motion.
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Old 06-12-08, 10:25 PM   #22
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OK. I think I found a solution to this dilemma. A 4 hr drive home leaves one with time to think...here goes..

Go to your local hobby shop and purchase the following....

1. A strip of .062 music wire
2. A strip of .055 music wire

Note: due to variances in manufacturing of the bike, purchase different diameters. The ones above was what I had in my workshop at home. They're like $1.50 for a 36" length where I'm at (Michigan, USA).

Cut a piece of each (I'm still experimenting on the length - see below). Once cut place one strip on one side of the screw and the other on the otherside of the screw. Basically your going to use both strips to take up the space between the anti-rotation screw and the groove on the handlebar post. Don't choose diamters that are so big they get stuck. You want a tiny bit of play so you can still raise and lower the handlebar post like it's suppose to. That's it.

With this method, you do not need to sand off the anodizing, add anti-slip compound, or install a new quick release clamp. You can make the strips of wire longer, and use a rubber band to prevent them from falling out. They just need to be short enough to allow the handlebars to go down all the way. When tipped upside down the wires will fall onto the head of the handlebar quick release, and the rubber band will keep them in the groove (haven't done this yet myself). Good luck. I'll post some pics when I get a chance.

Time for Mod:
Getting the stuff: 30min -1 hr (longer if you browse the hobby shop)
Cutting: 60 seconds if you've got a Dremel
Install: 2 minutes for the first try. 15 seconds the final try if you hold your breadth and keep from blinking.
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Last edited by Silverexpress; 06-12-08 at 11:43 PM.
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Old 06-24-08, 10:21 PM   #23
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I've ridden my Boardwalk 1300km and I haven't noticed this problem. But I do fold my bike every day to ride the subway and have to adjust the handlebars up to fold it and then back down when I ride it again, so the handlebar post never stays in the same place for a long time.
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Old 06-24-08, 10:33 PM   #24
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The music wire has worked out fine. I rode the bike for a commute distance of 26 miles total today, and the handlebars did not budge one bit. I've put close to 75 miles since I wrote post #22 above.

If my co-worker shows up at the site I'm at this week, I'll compare my handlebar post(s) to his with a digital caliper. He has an '08 Speed 7 with the silver handlebars.
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Old 06-24-08, 10:45 PM   #25
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Are you guys just not clamping with enough for or what? The same system holds seatposts in place on thousands of other low end bikes without this problem. FWIW, we sell hundreds of dahons and have never encountered this problem before.
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