cliff_cliff

Hi
I bought a Dahon D7 Speed, 2004 version for £100. This is the bike (EDIT - I'm not allowed to post photos or urls so difficult to show the bike)

I'm only going to be using it occasionally, not commuting everyday, but more for a trip here and there, throw it in the car etc.

Anyway I've noticed the handlepost is quite flexy at the hinge in a forward and back motion while riding. also the handlebars are misaligned slightly to one side. not sure if these things are related. not sure if that flex is normal? I don't have experience with these bikes or any other folders.

Looking on the internet I can't quite seem to find the name of the handleposts on this bike. It seems like they changed the design 2005/06. I'm just wondering if there is a proper problem whether it can be fixed? or whether the style of handlepost I have can be easily changed for the new version from 2005/06? or anything newer again?

I'm really not sure and any help would be appreciated. I'm hoping I haven't made a mistake.

Thank you.

cb400bill

Pic Assist - My Post Pictures by cliff_cliff | (bikeforums.net)

Ron Damon

Have you tried to tighten the two bolts that affix the handlepost to the fork steerer?

CrimsonEclipse

Handlepost (stem) by nature is a bit flexy on the older Dahons.
A wobble feeling will be loose hardware.
A flexing feeling is relatively normal.
Make sure the stem center fitting (10mm allen I think) and the 2 side pinch bolts are both secure.
The center bolt tightens the headset while the pinch bolts prevents the handle bars moving relative to the fork/wheel
The stem
If your handle bars are aligned incorrectly, you'll need to loosen the pinch bolts and align the handle bars left or right in the steering directions.

Newer stems had less flex but only a little less flex. You usually ride a dahon in the seat and not out of the saddle.
Some newer stems had a telescoping height adjustment, which is great for fit adjustment but bad for stiffness.

Good luck on the new bike!

Duragrouch

I disagree with the above. I had that exact bike, serial number indicates 2005.

The stem you have is MORE rigid, it is one piece, tapered chrome-moly steel, and well braced at the base. The later *telescoping* (height adjustable) stems have a good base of forged aluminum, but the telescoping clamp joint at the upper (smaller diameter) stem section is where you will get more lateral flex. This is why (I think) the Dahon Speed TR (touring) used the old stem, because with touring loads, handlebar forces when climbing will be greater. The rigid stem is the same height as the telescoping stem when all the way up, so if you like your handlebars in that position, the telescoping stem is no advantage, except if you have clip-on aero-bars, when swiveled up to fold, those can drag on ground when folded, unless you can shorten your stem to compensate.

Misalignment of handlebars is easily corrected; Loosen clamp bolt at base of handlebar stem, realign, tighten. Perceived looseness at handlbars, rocking, can also be loose heaset adjustment; Fold handbar stem, loosen clamp bolt at base as noted above, *barely* tighten very large center bolt above head tube (I think 10mm? allen), only enough to take out slack, overtightening will brinell (dent) the headset cups and steering will be lumpy. Retighten clamp bolt, bring stem back up. That over-center clamp that holds the stem up is adjustable, needs to be tight to not rock, just loose enough for you to easily undo it.

Handebar rocking sensation can also be loose main frame folding joint, that is also adjustable, needs to be tight, and I recommend also putting a locknut on adjustment so it stays put, otherwise you will be adjusting it monthly.

If you change the stem to the later telescoping one, there can be a compatibility issue: Your rigid stem has more of the fork steering tube sticking up to clamp around, the later telescoping ones used less tube sticking up; As a result, when I swapped out my frame (newer frame had telescoping stem) due to the problem noted below, but kept my older (more rigid) stem setup, I needed to also use the older fork.

Check the bushing between the seat tube and seat post; If (silver) aluminum, fine. If black plastic, replace immediately; The plastic compresses more than the aluminum, causing increased metal strain at the front horizontal slot at the top of the seat post, causing cracks there, and the frame becomes junk. The aluminum bushing also reinforces the steel seat tube in bending. Aluminum bushings are available aftermarket online. Make sure you get the inside and outside diameter correct. This crack got much worse over years and I had to replace the frame:



What is possible (same bike with later frame after crack above):

rickpaulos

Have you checked in to the recall notice on the Dahons from this era? I had two Speeds, one was a recall model. Dahon will only work with a bike shop to replace the parts.

Duragrouch

I think that recall covers only the aluminum telescoping stems. I have a later Speed D8 that was covered in the recall. I wish I had not brought it in. They swapped out the stem bottom only, and the next day I noticed the stem tilted to the left; The bored clamp hole was not square with the casting bottom. By that time, they had recycled my old stem. I mentioned it on here and a large Dahon dealer sent me a replacement stem bottom, I put it on, straight left to right, but the stem bottom did not sit flat on the top of the headset, bore out in a different direction. One of the things I learned in the automotive industry, is that often, "service" parts purchased at the dealer, did not pass production tolerances or specs, which matters more for a 3 or 5 year factory car warranty, but not as much for 90 day or zero warranty on service parts.

cliff_cliff

thank you for all these responses they're really helpful

cliff_cliff

This is really helpful. I'm at work at the moment but when i get in i'll post some pictures of my hinge etc. reading your post I'm not sure what you exactly you're referring to when you say clamp bolt at the base and center bolt above the headtube. When i fold the handlebar stem, it's kind of covered with a small metal piece/beam that's attached to both ends. and from memory there doesn't seem any obvious space to tighten something without removing that. but photos will help here so you can guide me?

the bit about the seat tube and seat post bushing is worrisome. that's something I'll have a look at. I hope to see no cracks.

Thanks again, I'll post some photos when I'm home tonight. Also thats a nice photo of your bike. looks amazing.

cliff_cliff

Hello I'm home now. I'm going to try and add some photos to this post and hope the moderator can help me out again. would appreciate it

the seat post does have the plastic shim but luckily i have no cracks. i see a replacement one at foldingbike[dot]biz. this works im in the uk. they seem to have a few versions, not sure which would be suitable (sorry it wont let me post links either):
they also have a 105mm version. which on for the bike? also re the above what adhesive would you recommend?

Regarding the handlebar here are the photos (please mod allow). you can see the centre bolt you refer to but not sure how to access it with the mechanism in the way? also it looks like that maybe a crack in the grey part at the base of the handlebar stem?? if so what are the implications?






thank you

cliff_cliff

reading it looks like the light grey bit that looked cracked is a plastic headset cover? on most of the examples i see they are black in colour not light grey. anyway is that something easily replaced with a spare? would i need to? thanks

cb400bill

Pic Assist 2

Ron Damon

I myself would replace the handlepost with a modern one, and check/replace the headset while I am at it. A new, modern, flex-free FnHon handlepost, for example, costs all of $35. Headset? $4.

Handlepost flex is no longer an unavoidable, normal characteristic of folding bikes in the third decade of the 21st century. Beware the advice of the gurus here -- one or two, fervent devotees of the Dahon cult -- who in 2024 still haven't gotten the memo.

Duragrouch

Seatpost shim: Says it's for Dahon, 33.9mm inside diameter same as seatpost, good. If they have different lengths, get the longer one, the longer the better, this spreads the bending load over a longer length of the seat tube, and that's good. If no frame cracks currently, I think if you replace the plastic with aluminum, you will be fine. (I wrote up a very detailed engineering analysis of the crack failure, sent to Dahon with recommendation to send all owners an aluminum shim to replace plastic, they blew me off, and no frame replacement either. I promptly sent the report to the USA Consumer Product Safety Commission.) I wish they made shims in stainless steel, stiffer and stronger than the aluminum, to better reinforce that area. Note that is slot on front of seat tube, loaded in tension in bending, due to seat loads with aft-tilted seatpost. Metal fatigue happens in tension. Later Dahons, starting with the aluminum frames and then the steel frames, relocated the slot to the *back* of the seat tube (like most bikes), so loaded in compression under bending, should be stronger.

Regarding glue as they mentioned, my shim has never tried to slide out when adjusting the seatpost up; The seatpost clamp is smaller ID on top, it holds the shim in place. (And yes, insert the shim in the seat tube *before* putting the clamp back in place on top.) However I'm not a "frequent-folder", so if you need glue, use a spot of glue, something rubbery. In fact, I put a thin coat of "anti-seize" (silver, for aluminum) in between the shim and the steel frame, to discourage dissimilar metal corrosion. Be careful to NOT get any on the inside diameter of the shim, as that may make the post slip, and it's very messy as well, like grease, but with fine metal powder in it. Don't get it on your clothes.

Adjusting the headset with the large allen bolt: I think you can hold the stem in a "halfway-folded" position to get access to the bolt, if not, you can undo the folding mechanism at the threaded adjuster I think. Remember that big center bolt will not adjust anything until you loosen the clamp bolt on the side, and be extremely gentle in tightening that big bolt, it is easy to brinell the headset, just finger snug, use the allen wrench stood on end with the short bend as a handle. After adjustment, tighten the clamp bolt.

Cracked plastic ring: I can't recall if that is just a spacer (to compensate for different length steering tubes on different forks, as mentioned?!), or is the top of the headset. If cheap to replace, replace.

cliff_cliff

i really appreciate your help here. i'll start tackling the handlestem this weekend and order the part for the seat and do that if it arrives in time. i'll be very gentle with the clamp bolt as you say. just a bit at a time and see where i am. regarding the plastic ring it does seem like a spacer. it sits upon the headset and on other videos it just pops off, so for now it should be ok with the crack, although i'll mention it to the shop i buy the seatpost shim from and see if they have anything.

I wonder the the usa consumer product safety commision would have been back in touch with dahon after you did that? im surprised they fobbed you off. when i searched cracked seat post frame after you mentioned it i found a few examples on the internet of that.

looking forward to get it going. i had a quick test ride when i first bought it and i really like it. the guy i bought it off was nice enough to put new tyres on, but theyre plain black and a bit wider than standard i think he said. fancy at some point ill but some tan walls on and also i want to change the black rusty rear rack with maybe a nice stainless or silver one. any advice of a little front rack?

i have another folder its a peugeot nouveau style 1970s in white. i recently re rusted some areas and got the wheels serviced and new white walls on. its a beautiful bike. i'll post a photo and ask for the mod to show it. cheers

cliff_cliff

also come to think of it im almost certain my seat post slot opening is on the back of the frame, not the front as in ur example. ill have a look tonight. seems strange as design is the same as ur cracked version

Duragrouch

To paraphrase Animal Farm, all stems are equally rigid, but some are more equal than others. I've wondered about the rigidity of stems on Bike Fridays, which use a slender (old quill) diameter tube, versus my old Dahon (much larger diameter) tapered steel stem, or the later forged aluminum Dahon stems. On the telescoping stems, the bottom half is very rigid, but the top half is much smaller diameter, and aluminum (1/3 the stiffness of steel for the same geometry), and transmits force through a short single-clamped joint, so is a bit more flexy, though not horribly so. Never noticeable in normal riding, only if climbing out of the saddle while pulling on the handlebars a lot (which is not my style, I don't pull that hard and mostly just use my weight when standing). I did note that long after Dahon had introduced the telescoping stem, they resurrected the fixed stem for the Speed TR (touring), my guess for more rigidity when loaded, and had a welded T at the top of the stem, connected to the handlebar with swinging clamps, to swing the bar up/down/forward/aft, to get some adjustability. I wondered how much flex was introduced by those skinny clamps.

You can get headsets for $4? That's cheaper than here. Although I actually haven't seen outside the bike, modern integrated headsets that are completely inside the head tube, for all I know, they are just a couple of standard ball bearing assemblies, so perhaps much cheaper than in the past.

Duragrouch

Based on year (which, by the way, is the second number in the serial number after D, should be a 4) I think the seat tube slot is on the front, you just have your clamp slot to the rear. The clamp slot position should match the seat post slot orientation, to get less relative movement between the two parts as you clamp it.

Duragrouch

CPSC never contacted me. Many agencies tend to follow the mood of government leadership, and it was during the Trump era, who didn't support consumer protections, they were a tool of big business. Agencies like our Environmental Protection Agency got killed during the Trump era, especially after him stacking the supreme court to conservatives.

Rear rack: Yes, the steel Speeds came with a steel rack, the aluminum ones like the Mariner came with an aluminum rack. But both racks are low over the tire, OK for strapping loads on top, but are fairly useless if you want to fit side panniers, because a) normal size panniers will be close to ground, definitely scraping on curbs you come close to, and b) won't hold the panniers far enough back for heel clearance. Take a close look at my posted bike picture next to the ocean; The rack is a typical large bike height rack, so top is 6"/15cm above the rear tire, that is common, but also, holds the panniers aft of the rear axle, the front of the pannier even with the rear axle, and that is harder to find, and is essential for pedaling heel clearance. Also what I love, the panniers are not hung from the top platform, there is another rack level 2-3" below the top to hang the panniers (and still tall enough for easy pannier clearance to ground and curbs), which makes it much easier to put on and remove, both panniers, and the trunk bag. They no longer make that rack, but others are made, some with lower sections that are interchangeable to vary the fore/aft position of rack. Many newer rear racks are narrow on top, for more streamlined, holding panniers further in, but I hate that, I want it wide enough for a trunk bag on top. Also, the far aft position of the rack and low rack seatstay braze-ons, required super-extra-long rack stays, much longer than came with the rack. Jandd sells those, as well as another brand of racks, I forget. A good bike shop that outfits touring bikes and is rack-knowledgeable should be able to set you up. Of late, I've seen less assortment of rear racks at the local bike shop, as they are out of fashion with bikepackers. I think this one meets all above criteria, but you'll still need much longer stays:
https://www.amazon.com/Axiom-Journey...dp/B009VU3RAU/

Front rack: The rack is generically called a "sixer", just big enough for a 6-pack of beverage, connects at the bottom to the V-brake pivots, like this rack:
https://www.amazon.com/Sunlite-Gold-...dp/B002MKHR6G/

It's actually designed for large wheel mountain bikes, but the distance from the fork crown to the brake pivots is the same on a 20" fork, so fits perfect, and perfect scale for the bike. Not designed for panniers but I hung'em (being careful to not overload with weight), old small rear panniers from the 1990s that used to be on my long wheelbase recumbent. I cut wood sticks to go between the front dropout and the forward rack top, zip-tied in place, not as bracing, but to just keep the panniers out of the spokes. The rack was $10 new. A proper front rack, attaches to the dropouts, proper size for 20" wheels, is about $50. Get one with a platform that is above the tires, it's handy for parcels; Dahon's front rack for the Speed TR held panniers lower and with no top platform. The rack weight, panniers or a small bag on top, will slightly "calm" the twitchy steering of this small wheel bike, give it some mass damping effect, and weight forward of the steering axis helps stability a bit, makes it want to steer in the direction the bike is falling.

The enormous space between the handlebar and the front rack, you can strap large parcels, or hang a small backpack from the handlebars by the shoulder straps, or hang a shopping bag from the aero bars as in my photo.

Note: Front rack may prevent you putting bike on some bus bike racks, that clamp around front tire. Clamping to frame would be better, if compatible with the Dahon monobeam thickness and height.

Pic that shows front and rear racks, bike folded on train:

Duragrouch

If you decide to use a bit of glue to keep the seatpost shim in place, if you have any, I'd use a spot of "Shoe Goo", it's a semi-liquid stuff that dries to be like a hard rubber, for patching the soles of athletic shoes. Or any other flexible and waterproof adhesive. An adhesive that dries hard, like epoxy, is no good, will fracture from the flexing of the clamp joint there. I don't recommend gluing all the way around, would be impossible to remove the shim if needed; Try first a small spot perhaps a centimeter wide, opposite the clamping slot, so in back on your seat tube, because opposite the slot is the place of least movement in the joint. The slot on the new aluminum shim, the slot in the frame tube, and the slot in the outside clamp (called a "turtleneck"), should all line up; On your frame, I think that is forward.

Many revisions to my post previous to this one; If you read well before seeing this post, you may wish to reread it.

cliff_cliff

just comparing ur photo of the crack above it seems like my whole frame is the reverse of yours with the hole and clamp on the opposite side of the frame facing to the rear.

also just looked at my serial number and it starts DG4. underneath is a sticker indicating it was made in Macau

see this photo (please mods)

Duragrouch

Interesting. I'll await the pic. All the ones I have seen with plastic bushing and that age, have the slot in front. I'll have to look up my Dahon serial number guide to see if that G means anything. Dahon may have just tooled up fresh in Macau and introduced the slot change there before their other factories. I don't recall what my original frame said as to source, whether Taiwan or China. My current frame says China, but Macau is part of China and they usually label by country, not by state, province, or "special administrative region" (Macau).

Checked serial number guide, no indication on G. However, one of my later Speeds (D8) says DG5... and it has a slot in back. I had guessed it was 2015 manufacture, but it may be 2005, based on what you are seeing. G may denote the slot design change, or Macau manufacture.

Even if slot in back, change out the seatpost shim/bushing to aluminum, absolutely, positively.

cb400bill

Pic Assist 3 - https://www.bikeforums.net/g/album/32619610

Duragrouch

Peugeot: There was another thread about such, their bike looked to have a strange wheel size between 20 and 24 by my eye, and that was confirmed. Yours' looks closer to a more standard size.

Dahon: Sure enough! Yours' has an aft slot. Just weird that it still has a plastic shim. Probably dahon using up stock of them before going to aluminum. Glad to hear you are upgrading that to aluminum, there is no more important upgrade. ***EDIT: UNLESS, it has already been replaced with an aftermarket shim that is *black anodized*. Look at it close, it should be evident if aluminum or plastic.***

Additional: I think the shim top should be under the clamp top (turtleneck), but looking at it closely, it looks like it could work either way. Notably, the rim on the top of my aluminum shim, looks to be a hair smaller diameter than the seat tube outside diameter, so the clamp is squeezing down on the seat tube, not just the rim of the shim, there's a tiny gap around the rim of the shim. After clamping the new shim in place, shining a flashlight in that area, should tell if the same.

cliff_cliff

hello, i can post pictures now hooray. yes it was indeed a plastic shim here's a photo:


the new shim is in. a photo below, not sure what you mean above re should be clamping down on the sim as well? do you mean it should be clamping down on the shim lip? i spayed some metal lubricant in there to help against corrosion, obviously there was already surface rust but nothing too bad. didn't need any glue, once its in it seems to grip on its own quite well and i haven't noticed any slipping yet or movement




regarding my handlepost flex issues, i followed your advice. the 10mm hex was already grip tight, but i loosened it and made sure it was gentle tightened no more than my grip. the flex or what felt like backward and forward movement was still there. i then decided to tighten the hinge mechanism itself, tightening the bolt post like in the below picture and video. it worked a treat. first i tightened it too much and couldn't close it, so i just worked with it until it felt like it was a good pressure but not a tight pressure and the handlepost is solid now. photo of the bolt I'm talking about below and video from dahon for others in a similar situation



video from dahon

I also straightened the handlebar as you suggested. other than that I've given the bike a nice cleanup with some muc-off solution and a spray with some metal lubrication spray. its looking nice and shiny. degreased and wet-lubed the chain.

only two issues I've come across. first the handlepost hinge has a little metal spring clip that it loose. i don't think loose enough to come off, but definitely not tight as it should be. I'm not sure where i would get such a replacement part. its tiny. see below its a tiny clip on the right off the bolt post



the other issue is i also want to tighten or make sure the main frame hinge is tightened right. i don't even know how that should feel as I've never had a new version to compare factory tightness to. any advice. I'm also not sure how to tighten it. in the photo below do i first loosen the screw on the outer side and then tighten the little bolt post you can see and then re tighten the screw? any help appreciated.