Alum welds
 

This is my beater bike that is use to ride MBT's and pack in a suitcase from time to time over the past 3 years. I inspect the welds on a regular basis and have not found any cracks. The welds look beefy to me. Nice weather today. The maple sap was not very sweet.

For MBT's I do three things: 1) drop the handlebars, 2) drop the seat, 3) drop the tire pressure.

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Certainly not the worst 'row of dimes' I've ever seen.

Welding aluminum's an art form that takes patience and lots of practice to do well.

(That pink bike hung up in the tree there as a warning to unwary bikers before they enter the trail?)

My experience cracking an aluminium (6061) frame is not that it fails at the welds, but rather next or close to the weld. 6061 is particularly vulnerable to HAZ (heat affected area) cracks beside the weld. Al is very thermally conductive and expansive so the area adjacent to the weld heats up during welding, expanding. If it heats up excessively and/or cools too fast, it results in potentially weaker material.

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6061 with cantilevered chainstays still going strong after eight years of service including light off-road and touring.

About a year ago, someone posted an image here of a cracked Al frame, and the fracture was in the area next to the weld, not the weld itself. This is not to say, of course, that welds don't crack, but rather to say that the weld might be pristine but the frame can still crack in other sections. That's what I look at and for in my Al-alloy workhorse. What Al alloy is your bike?

Nice new fender. You're welcome.

I believe it is 6066.

Section 3: Frame Materials
This section explains the different frame materials used in the constructions of ZiZZO Bikes.

Ferro: High Tensile Steel
Campo: High Tensile Steel
Via: 6061 Aluminum Alloy
Forte: 6061 Aluminum Alloy
Urbano: 6066 Aluminum Alloy
Liberte Plus: 6066 Aluminum Alloy
Marino: 6061 Aluminum Alloy
e-Forte: 6061 Aluminum Alloy

thx for the fender tip. it works well.

just a tip up; Campos made before 2025 were also 6061, but had a hi-ten fork and threaded headset.

Aluminum welds have several caveats.

First, some alloys like 6061, require post-weld heat treating to bring back up to full strength in the weld heat-affected zone. Notably, 7005 does not, it was designed specifically for bike frames and to not require heat treat after welding.

Second, weld geometry matters; Most of the welds on that zizzo bulge outwards (convex) at the weld toe, where it meets the tube, and this acts as a stress riser. This can be partly mitigated with a smaller weld bead at the toe of the larger weld. Cannondales were notably post-weld strip-sanded ("dressed") to a smooth concave blend with the tube, without undercut into the tube. Now, notice the top-front weld where the seat tube meets the top tube (just barely visible in the photos above), notice that weld is NOT stack of dimes, it is smooth, and better blended; This is not from sanding, they are using a more advanced weld process, I believe called puddle welding (which I think requires the frame to robotically rotate to keep the weld on top when molten due to gravity), because that area is highest stress, and critically in tension, from aft moment on seat tube, notorious for fatigue cracks in that area with normal stack of dimes TIG welding. That better weld is not as good as a careful hand sanding, but better than standard TIG weld. It also precludes them needing an added welded corner gusset there, like on a Dahon Mariner frame, which adds strength, but I have still seen fatigue cracks just above the gusset, due to the TIG welding, right at the weld toe on the upper front seat tube.

informative comments. I took another look at the welds and YES the seat tube to top tube weld IS more blended than the other welds. I have given it a good beating over the years. the components are low end, and the brakes are somewhat cheap, but the frame is doing well.

this speedster version of this bike (same bike, black colour) is 23 lbs as configured: gel seat, grips and aero bar mounts, pump and bottle holder, 58T chain ring.

Is aluminum material the go to material for a light weight folding bike?

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Nice homebuilt you have in the garage their A2022! I'm curious how long it took you to built that?

(You been flying a long time?)

For what it's worth, I once commented on the Zizzo Facebook page about jumping curbs and doing wheelies with my Liberte and the official Zizzo response was something to the effect of, "You might not want to do that."

I didn't take it as a critique of aluminum as a material (after all many mountain bikes have been made of aluminum) but rather as a comment that the bike was not designed for such forces.

You fly planes though, so I assume that you know all about risk management, and your visual inspection of the welds demonstrates that. My biggest concern would probably be the hinge. Not necessarily the hinge weld, but one of the smaller components that might be stressed or fatigued beyond its design specifications from repeated shenanigans.

Keep on keeping on.

agree. I also think rider weight is a factor. several years ago I was 195 lb, but now 165, so less stress on the frame.

I bought it 50% complete and it took everything I had to finish it in 3 years while working a full-time job. I have been flying for 49 years. My wife calls it the "rattling beer can".

For lightweight these days, carbon fiber composite is the go-to, and, you can make the layup directional, so more longitudinal flex for good ride, but 45 degree layups for good torsional stiffness. However, it's more difficult to do the hinge in CF, I suppose it can be done, but usually, it's CF bonded to an aluminum hinge or other hardware. Before CF, aluminum had its day; You can only go so thin on chrome-moly steel before it gets difficult to weld, and even with brazed lugs, very thin means easy denting, and possibly localized buckling and wrinkling under high stress. Aluminum, high strength versions, are still 1/3 the mass of steel for the same thickness, so can be thick enough for dent resistance, while still going oversize in diameter, which makes for a frame that is lovely stiff for sprinting (torsional stiffness is proportional to the 4th power of radius/diameter, so even with 1/3 the material elastic stiffness of steel, you have a net gain with aluminum), however, with a homogenous material, so equal stiffness in all directions, you end up with a bike that has a stiffer ride, such as my '89 Cannondale racer (frame weight 3.0 lbs), though many say that is more due to the frame geometry, with "steep" 74 degree seat and head tube angles. It's a sporty bike, and I eventually fit 26/28mm tires, a close fit, I had to just barely dust the front derailleur with a file to creat tire clearance on that short wheelbase.

Folding bikes have critical high stress points. Dahon's aluminum frames save about 1.5 lbs IIRC, but my preference is their older 4130 chrome moly steel frames. I have also made an improvised "Deltech" cable to greatly reduce stress at the hinge.

how much tension do you put on the cable upon installation and no rider?

I'm using a piece of kevlar I had laying around. UHMWPE (AmSteel, Dyneema, etc.) also works and is more common now. Anything ultra-low stretch. (The kevlar is painted black on the outside as it has low UV resistance, that's how it came. UHMWPE is better and comes in a number of colors.)

Tension: I don't know. I don't have a threaded adjustment, I would have done that (like OEM Dahon Deltech) had I made one with stainless cable at the sailboat rigging shop. I still would have needed high-strength line loops for attachment at the head tube and bottom bracket, due to no welded tabs. (I think my setup may be superior there, as Dahon seems to have yanked Deltech off aluminum frames, my guess was that the small welded tabs were fatiguing at the welds. Deltech is still on their steel frames, and may have returned on the aluminum ones by now.)

Kevlar and UHMWPE needs a very non-slip knot. I used an 8-bend. I made a loop around the head tube and bottom bracket shell on the left side; putting it on the right side, I'd be fighting the tension every time I folded it. So I have two strands, so 2X the tension for pull. I made the knot loosely while folded, began to unfold the frame, realized it would be too long a loop, shortened it, unfolded, the loop was just short enough so that to fully unfold, I needed to lay the frame flat on the ground on the left side, and use my foot to gently push it to fully unfolded, then I latched the hinge. With an 8-bend, you need to get it right the first time, hard to undo. You could instead use an adjustable setup like a trucker's hitch. Knot has not slipped and line not stretched in 4 years. So, tension is basically as tight as I could make it, while still being able to unfold it with only a slight push at the end to snap the hinge "over-center", and I can do it now with my hand, without laying the bike flat and using my foot, but it has plenty of tension. Line can come off BB and be lost when folded, so be aware.

Photo before securing ends of line; "Lighter than air, stronger than steel, cheaper than dirt." The holy trinity of mechanical design.

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4130

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Oh I know. Plus, knowing I can add an improvised deltech cable, means I don't need Dahon's fancy newer hinges like Jaws and Jaws II, the sidelatch hinges now are plenty tough enough. And, I can get my desired disc brakes, and quality ones at that. IF, we could get FnHon frames here, and that situation will probably get worse, and not better.

I will remember this trick if I have a cracked frame and need to get home.

Those must be some pretty mild MTB Trails to be riding a bike like that on them.

yes, they are easy trails and I am an old, retired guy.



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Well, it's strongest before it cracks, so, chances are, if at the hinge, it will fail to completion, catastrophically (actual engineering term), so best to prevent. Cracks at the top of seat tube will give plenty of notice, happened on another frame (but didn't see them early enough), can't be remedied by this. A line from the top of the seatpost to the front of the frame would greatly reduce stress, but prevent low-stepover boarding.

How much would you be willing to pay for a disc-brake, 4130 chromoly FnHon Storm frameset?

That's an excellent question. I don't know, because I haven't investigated the cost of disc wheels and parts here, but that's more a question of total build cost, not frame per se. Plus shipping costs from your part of the world. Labor, that's zip, I actually enjoy it, first thing I do with a bike (usually used), is total overhaul.

I like the look of those wheels you've used that appear to be machined betweed the spoke holes for lightness, but are then thicker material at the spoke holes, that looks durable in fatigue.

We'll see how this whole trade thing sorts out. I'm in a little less critical situation now, having moved my rim brake pads down a bit toward the axle (right on the inner corner), to counteract the rim sidewalls being concave, to put off need for a disc bike. And the deltech cable eliminated my need/desire for the newer bifold hinges. So an FnHon Storm frame would do it, but only for the disc brakes, everything else is now fine on my old 4130 Speed. Well, it needs a handlepost that opens at the handlebars (my ancient one is a one-piece clamp style, would require removing stuff on half the handlebar to come apart) to come apart easy for air travel packing.

I have to take an air trip soon, but don't plan on staying long, so will do it sans bike.

I ain't talking about shipping it to the Homeland from my current location, but rather bringing them with me to the Homeland. But I need to know how much people are willing to pay, and therefore, whether it's worth the effort. The question remains.

Those Litepro wheels that I have in the Storm have disappeared from the market. But new players have emerged. I've been satisfied with the performance/durability so far of these MXL jobs that sell for under $100/set.

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24-, two-cross, straight-pull spokes

Yes, those are the wheels I was talking about, if that is machining between the spoke holes, and not silver reflector stickers. Not if they are simply lighter, but if the rims are on the thick side, they mill away those areas, and they are still thick and strong at the spoke holes.

Frames: Gotcha. Well, shipping here isn't cheap either, but Seattle is a natural place to connect thru. I probably won't upgrade this year, I got too many other irons in the fire, plus need to make space in my small rented room, or offload my Speed. My nephew has never ridden a bike and has none and will be doing college somewhere (TBD) in the fall, so depending on where, that may be where my old bike goes.

Ok, so I'll never get an answer of how much you would be willing to pay for one. I wasn't asking about or interested in your life complications, family relations and personal admin arrangements. All I was interested in was a three digit number. Thanks.

Ah, OK, sorry. Umm... with absolutely no knowledge of what the wheels, brakes, and other parts would cost me, my guess would be between $200-$300 as a reasonable frame cost. Less would be expecting too cheap on my part, and more might go over budget for the finished build, as I can't get parts nearly as cheap as you, at least I think. I haven't bought anything off Ali yet.

Dahon may get a clue and sell in the USA, their Archer 20(?) with normal disc spacing and hydraulic brakes, and the frame is aluminum but has extraordinary looking welds that don't look like TIG. But I'm not holding my breath on Dahon's marketing intelligence.

Well, Mini-velo frames run $300-800. I'd think it would be around $400, but there isn't much to compare really. The FnHon storm looks like a good starting point for a new folder. Planning to smuggle some in ,Ron ?
The Origami Lotus is down to $459, don't know who made the frame, but it's a clone of an FnHon, unless they make them real cheap . The Lotus has an assortment of weird off brand parts on it which helps with the price.
I'm shopping for my next folder, and haven't narrowed it down yet.

No smuggling. It would all be above water and within the personal importation allowance limit of $800. Yeah, I'd bring a couple if I could sell them for $400 a pop.

Fnhon Storm on Aliexpress:

https://www.aliexpress.us/item/32568...yAdapt=glo2usa

Thanks! With shipping, it's over my budget, but that assumes buying components here. Also, it includes the handlepost, that's a good savings; The longest fixed one is about 3" shorter than my desires, but the adjustable option should do it, though I prefer a fixed post in the correct length for me. If getting the frame from Ali, in for a pence, in for a pound, I'd source everything there, especially if the shipping is grouped so that same or near cost as the frame alone.