staehpj1

I have a Helios and hate the stock front mast. It is too flexy and impossible to get the bar low enough or far enough forward. I read some threads about replacing the mast, but am confused about exactly what mast will work as a replacement. I need something lower and less flexible. The bike has been stuck is storage and forgotten for quite a few years because I found it pretty unpleasant to ride very far or very aggressively. I have been considering getting it out of storage and giving it a new life if I can solve the mast issue.

Advice?

rhenning

First use the right term. Masts are on boats and stems are on bikes but a picture of what you want would help clarify what you want. Roger

staehpj1

I have seen a number of terms used by folks selling the part. Handle post seems the most common. The stem may be integral with the handle post or be a separate part so I'd hesitate to call it a stem.

FWIW one definition of mast is "any sturdy upright pole used as a support". I have heard both the seat and handlebar posts on folding bikes referred to as "masts" quite a few times in the past.

I was intentionally vague, because I am not so much asking for a specific part as for a general answer of how to manage to get rid of all that nasty flex while getting the bars lower and further forward. I wanted to leave the question very open to not rule out possible solutions. That said, what I suspect might work is a shorter more rigid handle post. I don't know which ones might fit properly on the Helios though.

Schwinnsta

Google Dahon Handlepost Replacement

You need to know which type of post. Many older ones were expanding wedge type, threaded, modern ones mostly threadless. Myself, I would remove yours just to see the type you have. Then you could go online and see what is available.

The knock on Helios was that it was too flexible.

If you do remove the post a pic to the thread.

staehpj1

I'll get it out of storage and take it apart. When I do I'll post a picture.

Nyah

In in the context of folding bicycles, extenders such as this can serve the same purpose of a stem.

Although they aren't usually found in a large variety of lengths, the way that "road bike" stems are.

That one is by Litepro. I believe its length is 50mm center-to-center.

They come in different clamp diameters (26mm and 31mm), so, make sure it matches the handlebars you plan to use.

As for a stiffer handlepost, the biggest improvement comes by limiting your handlepost choices to ones that don't have any height adjustment mechanism. The telescoping mechanism adds a lot of flex.

Ron Damon

Post a pic of what you have, the head tube and the handlepost, and we can take it from there. If it's stock stuff, it's easy peasy to install/replace. There are sizes, shapes and angles aplenty.

Fentuz

Hi,
I did a thread about my helios and how I learnt to modify it on the cheap. Helios... race bike type or TT?
I didn't like the telescopic handle bar stem/post either so I fitted the one you find on Speed TT and Mu SL (and many others). This type is shorter and has a T fitting that required something like the litepro stuff above.

However, while I generally like the litepro bite, do NOT use this "extender". The clamp are made of smooth soft anodized aluminium and when you get on rough road or get out of the saddle a put some weight on the front while climbing a hill, the extender stem collapses... The genuine product, Syntace VRO adaptor, fitted by Dahon and Tern is properly designed with a knurled inner surface and hi tensile bolts; these 2 things allow adequate clamping a since fitted, I've never had any other issue (even off road).

Ron Damon

Those stems -- or stem risers as they are called here -- are not designed for 'T' type handleposts. They are designed for 'regular' handleposts with knurled clamps that clamp on the knurled tube spanning the two stem riser clamps.

Fentuz

OK however, as per your picture, it does not clamp on the knurled part of the handle bar... like I said, the proper dahon/Tern equipment are designed to clamp properly and there is a oversite with these specific litepro assembly.
Other than that, I like and use many other litepro product (even on my expensive bikes...).

Ron Damon

Ok, gotcha.

staehpj1

I'll get the Helios out later this morning after my morning ride. I am excited about the possibility of finding a new life for this bike since it never really worked out too well in the past. I didn't care too much for the ride and strangely enough a regular non folding road bike wound up fitting better in our sailboat at the time (folding proved to not be an advantage when we decided to use seat lockers with long narrow openings). Any way I have no immediate use case for the bike, but longer term have some trips in mind were it would be very nice to have a folder.

BTW, Is there any chance your drop bar setup will fit in the 62" samsonite oyster case? It is a bit of fiddling to get the regular bar setup in so I am guessing no, but if you know for sure one way or the other I'd be interested. I'd think a bull horn bar might have a good chance. Not a priority or anything, just curious. Given the level of fiddling to get it in the case and the fact that many airlines have more liberal bike baggage policies I don't know if I'd ever bother to try to pack it in the 62" case for a trip again any way. When I did in the past I always worried that TSA would unpack it and be unable to get it back in, despite me including packing instructions with pictures. The bike did get loaned to a frind who took it to a year's teaching gig in Spain. She then wandered europe for a bit. So it is more well travelled internationationally than I am.

staehpj1

Okay so it looks like a split wedge to me. I think these pictures show that without need to take it apart at this point, right?

So what is the next step? I assume I am ready to start figuring out what split wedge post will give me a handle bar position that is reasonable. I'll assemble the bike and take some pictures and some measurements unless someone says I need to do something else..

staehpj1

Okay so I did some measuring and I am closer to being okay position wise than I remembered. The bike has been in storage for years and when it was last used it was by other family members, I've actually ridden it very little. I had fudged the saddle position by moving it back more then the knee to pedal spindle rule would advise ot get the saddle further from the bars. I cut the inner piece of the telescoping post to allow it to drop as low as possible. So as a result it looks like it might be more useable than I remembered. Now it is just about level with the seat and it used to be unable to get below several inches above the seat.. I would like to put the saddle back where it belongs (fore and aft) and still have the bars where they belong retative to it, but I might manage that with an extender.

The problem of the flex remains. I need to ride a bit and see what I think about that at 71 years old I may find I am less strong and flex the frame less. Also it occurred to me that a lack of low gears may have led to mashing a low gear and made for more flexing more of the time. So I think I'll do a bit of evaluation of where I am with the bike. Perhaps some gearing changes would help as much as the post swap.

staehpj1

Okay so I went for a ride and it was surprisingly okay. Maybe the fact that I aged in the 5-10 years since I rode it was a factor. Any way the flex wasn't bad and the fit was close with the cut down post. I figure that with an extender I can tweak the fit pretty close. What extender would you recommend?

After all these years the bike may actually become one that I ride.

Fentuz

this is a very early stem. you could one of these with the VRO from Syntace
or
one of these in bent version/gooseneck

if the frame flex a little, you can tighten a little the downtube hinge;1/4 turn at the time which increase the cam interference and therefore clamping.

Fentuz

Some people cut the telescopic tube (at top below clamp), press in a star captive nut fitted with a standard steerer cap and then they fit on the tube a standard stem... doing that means that you need to do some measurement and possibly use shims but it is doable.

Nyah

Thanks, Fentuz, for clearing up about the LP product I mentioned. I assumed it would work. I own an example of it, but, never 'had to use it', since my handlepost already puts the drop-bars at the correct reach for me. Will not recommend again. Sorry, Staehpj.

I stand behind what I said about getting a non-adjustable handlepost. If you don't need to raise/lower the handlebars, the one-piece handlepost is a good way to minimize flex.

Schwinnsta

Will those even attach? He has a threaded type stem.

Fentuz

that’s good point; those modern posts require matching fork and possibly need cups.

the pre 2004 post won t be compatible with anything currently on sale

Fentuz

yep and it also lighten the bike… hence I done it.


basically, if somebody want a “sport” or at least performance orientated Dahon/tern, they should start by looking at the dahon speed TT, tern verge x18 and X11 spec and see how the manufacturers upgraded their models.

i reviewed that and then search for modern equivalent or better thing within a limited budget. No rocket science, just several hours on front of a computer

staehpj1

I am probably at the point where I am willing to tweak it a little to get the position right and call it a job, but not do a lot of upgrading. If I decide I want a real nice folder, I probably am better off just buying a new one higher end one or at least a newer one.

On the telescoping post being less rigid... That is true, but since the inner part is completely inserted the effect is minimized. I could even discard the inner part and have someone weld a piece on makeing it a tee post. I don't plan on doing that, but it would be an option since the height would be about right.

Ron Damon

That's some old school, bro.

staehpj1

Yeah, still like new though. Been in storage for ages.

Schwinnsta

Solid masts that fit your bike were sold by Dahon with your bike. Finding one though will be difficult. They are out there. Part of the search problem is people call them stems, masts, handlebar posts (probably the most accurate and used by Dahon). Save an eBay search Dahon handlebar post, stem, mast. Don't specify Helios.

I would also try contacting Dahon USA. I would have said contact Thor, but he retired.

Helios, due to its lightweight, was a popular bike.