C'mon vrf you're old school like me, you know full well where the max stress is on a folder and it's definitely not the hinge..

 

I thought it was the hinge, but glad to know that I'm wrong. Is it the weld where the downtube meets the head tube, given that most folders have no top tube.

 

Our folders. Mine is the yellow.

Edited March 21, 20197 yr by harrys

On the subject of conversions....how not to do it.

Guys like that are dangerous. He's got a thin aluminium rack between his frame and axle on a full suspension bike, and he has four SLAs sitting on it. As soon as his axle starts going up and down, it'll shake the rack to pieces and his batteries are going to get spewed all over the road.

 

I was going to message him about it, but then spotted that he had a follow-up vid, where he said he'd had a lot of messages about it and admitted that he hadn't gone far on it, but he still didn’t see it as a problem!

Yeah.. I though that vid would go down well, at least the chap's still in one piece. I hope his bike is !

 

@ Harrys

 

Ah, I see you have a couple of Yans bikes good choice, didn't realize you were in the states. He certainly knows how to design a good bike, rock solid no problem powering them up. I used to chat to Yan back in the days of the 'Great Tern cracked frame debacle' That changed the way folding bike frames were made.

 

As for frame stress.... when you press down on the pedals of a bike the whole frame distorts but a traditional diamond configuration handles it perfectly, it's the ideal shape hence it endures to this day.

With a folder things are different, with no top tube all the stress is torsional along the tube connecting the front wheel to the back, a folder literally twists along the frame.

Imagine taking a long solid rubber tube and twisting one end one way and the other end the other way, that's what's happening with a folding frame. Now the rear section is strong with not much movement because it usually has it's own small triangle as Neal rightly pointed out. The front end however has little or no bracing so the whole frame tube twists in relation to the rear section. Now consider this, the main tube isn't one whole solid section as it's a folder so flexing cannot be absorbed readily in the rear half of the bike. The hinge has to take all that torsional twisting force. ok, so how come it's not the Achilles heel ? Well you can make a hinge as strong as you like on a folder but it's still all down to the welds and how the frame tubing is connected to the hinge itself that matters.

The weak point is that weld that joins the front section of frame tube to the hinge, if something gives you can be sure it will be there. That's why Tern had to do a recall on thousands of it's frames thanks to design & weld problems. I'm pleased to say I played my part in that but I don't expect a Knighthood from the Queen !

These days folders are much stronger, hinges and frames are better designed at the fold with internal raised sections and indents that lock together to keep the hinge more rigid, internal abutments in the frame tubing by the hinge and extra material welded to the frame around hinge to create a greater weld section. Better hinge bolts and latches all make for a safer folding bike, that's why I still maintain it's all down to cost. Cheap bikes just don't have that attention to safety detail that the more expensive machines possess , and hence IMO at least don't make ideal candidates for conversion to e-bikes.

Seems to me that you've just made the best arguement FOR converting these bikes.

The motor in the rear triangle will put a rotational force onto the dropouts but will be spread by a torque bracket. This force will have a steady nature, not the pulsing nature that comes from the rider pedalling. That force will still be there, of course, but my guess is that it will, mostly, be lower, only maxing out on hills.

As to the oscillating strain put on the hinge and welds - I see your point. However the design can either take this or it can't. If anything, adding a rear motor serves to alleviate some of this strain as the rider does not have to work so hard.

 

This is not a commercial conversion, it's favour for my neighbour. The bikes will spend most of their time folded in the garage of his camper. Used mostly for river/canal path rides, with the odd jaunt into town for a bottle of wine and a baguette. Purely leisure rides with nowhere to be at any time and no point to prove. The conversion is going ahead subject to final parts selection.

 

Ross, your investigation on the suitability of folders, in general, for conversion may well have merits beyond my scant engineering knowledge. But this is a thread asking for component advice, please start a thread where the engineers can present cogent facts to each other. I will read it with interest.

 

For myself, I would never have a bike with anything less that 28" wheels. I just can't take them seriously:oops:. Folders have never appealed or been needed. So 700c and double front ring all the way for me.

Now I've got the rear wheel out (so I can order a freewheel removal tool) and I see that the dropouts are 130mm. Can anyone confirm if a Q100H will fit? I seem to remember standard dropouts being 140mm. As the rear triangle is so short I can't see this springing a whole 10mm.

I've never had one that didn't fit, but those folders with a big fat seatstay that curves round from the main spar can be very stiff. Yours will be OK. No disc brake saves you about 5mm because you don't need the spacing to keep the disc away from the caliper and stays. You can reduce the motor's width with a narrower freewheel, like a 5-speed one. How many gears are you planning?

It's got 6 on it with a twist grip changer. Frames aluminium whereas the forks are steel, so a front hub is still a possibility.

 

 

So I've got about 11" to spring 5mm/side. I can do about 4mm total with my hands, think it'll go?

I might be a pain in the R's I'll admit that , but I'm also a responsible pain and I have to say springing aluminium is a no no. I'll leave it to the experienced guys to tell you why that is.

I'm an experience guy and I'll tell you it's absolutely no problem to spring an aluminium frame. The only time I've seen problems mentioned is on forums, where the theorists, who never tried it, do their scaremongering. It's another urban myth. With a 6 speed freewheel and no disc, your motor will be narrower than normal.

 

Just about every bike with a Q100 or the even wider Q100C had to have its frame sprung a bit to get the motor in. Have you ever heard of someone that broke their frame because of that? In fact how many broken frames for anything can you remember? About 3 or 4 in ten years is my count. One was a Haibike with a broken suspension bracket and the other three were all broken seatposts due to dodgy design.

Edited March 22, 20197 yr by vfr400

OK, so there's a difference of view on the flexibility of aluminium, I've heard that ally frames give a harsher ride because of it's lack of flex. Can't say that I've noticed.

The issue here is, am I going to be able to get the motor axle inbetween the rear forks. I can see how not having a disc makes the motor less wide, but I'm not clear how that would affect the axle length. Is it because there are spacers or nuts that can be removed from the axle?

Obviously I've got to be uber careful here because it's not my bike and I also don't want to end up with two kits I can't fit.

Thanks for all the help guys.

No offence intended and I hope none taken but I have to say vr's advice on ali frame springing is incredibly irresponsible.

Aluminium has an almost crystalline structure, it's soft but not malleable as such, that means when bent it actually cracks which results in the material eventually falling apart. Have I known it to happen ? dozens and dozens of times. No so long ago a pal of mine had a near miss when we were coming down a really steep hill at nearly 40mph and an alloy bracket he'd fashioned gave way (stress fracture) and almost went into his front wheel, a real close one that. You also risk fatiguing the welds holding the rear triangle together, it happens to planes all the time that's why they're constantly X-rayed. There's a saying in the cycle world when it comes to frame springing ' Steel, sure, Titanium yep ok, Aluminium..never ! ' Don't believe me ? Google is your friend.

Incidentally I've been cycling for over 65 yrs (gulp) that doesn't make me a genius but it does indicate a tad of knowledge. Bending aluminium to suit something it was never meant do:eek:, this should be an enlightening thread.

No offence intended and I hope none taken but I have to say vr's advice on ali frame springing is incredibly irresponsible.

Aluminium has an almost crystalline structure, it's soft but not malleable as such, that means when bent it actually cracks which results in the material eventually falling apart. Have I known it to happen ? dozens and dozens of times. No so long ago a pal of mine had a near miss when we were coming down a really steep hill at nearly 40mph and an alloy bracket he'd fashioned gave way (stress fracture) and almost went into his front wheel, a real close one that. You also risk fatiguing the welds holding the rear triangle together, it happens to planes all the time that's why they're constantly X-rayed. There's a saying in the cycle world when it comes to frame springing ' Steel, sure, Titanium yep ok, Aluminium..never ! ' Don't believe me ? Google is your friend.

Incidentally I've been cycling for over 65 yrs (gulp) that doesn't make me a genius but it does indicate a tad of knowledge. Bending aluminium to suit something it was never meant do:eek:, this should be an enlightening thread.

This is what they say every time someone mentions stretching a frame to put in a motor. Nobody has broken one yet.

'There's always a first time' Besides do we know for sure no one has. Springing won't necessarily crack a frame in an instant, what it does do is weaken it's integrity. So you get some underwear but it's too small...no problem it'll stretch with wear, of course it will, but what happens to the elastic ? ok hardly the same thing but you get my drift.

Fact is if you stretch aluminium it compromises it's integrity, that's not me thinking out loud because I'm bored it's a scientific fact. Can't change the laws of physics I'm afraid.

Fact is if you stretch aluminium it compromises it's integrity, that's not me thinking out loud because I'm bored it's a scientific fact. Can't change the laws of physics I'm afraid.

 

Aluminium 6061 has an ultimate tensile strength of at least 290 MPa (42,000 psi) and yield strength of at least 240 MPa (35,000 psi), Young's modulus : 68.9 GPa (9,990 ksi) Elongation at break: 12–25%.

The last bit (12% elongation before break) is an important point.

When you spread 5mm on a 20"wheel, the maximum elongation of the tie at the weld where the two branches of the rear triangle are tied together near the bottom bracket is roughly (5mm/130mm) * (100mm/250mm) = 1.5%. It's much more than spreading 5mm on a 26" or 700C frame. However, it's not a huge risk.

Edited March 23, 20197 yr by Woosh

WOW!

This is getting way beyond my pay grade.

I know that aluminium stress fractures, on repeated bending, easier than steel. But this will be a static bend, won't it? In other words once the stretch is made it stays there (the 140mm axle holds it apart) it's not a repeated action.

 

I don't know how you derived that formula Tony, but I assume that the 250mm is the measurement from dropout to the chainstay tie. If so, then the actual measurement on this bike is 270mm. When I plug this into the formula I get 1.42%. I know - confirmation bias:( (By the way, neat maths for a quarter to six in the morning. Is that before or after coffee?)

 

I do see your point Ross. Intuitively I know that aluminium is not as maleable as steel, otherwise I wouldn't be hesitating.

I think all I can do at this point is talk to my neighbour and see if he wants to take the risk or not.

There's always the front hub option.

Another thought. In all this I still don't know if the Q100H axle is actually 140mm or not.

I have just found a thread on ES. A guy there called Motomech reckons that all Q100 series are 135mm dropouts. Now with swmbo holding the tape measure, I'm able to spring the chainstays to 134mm with my puny arms.

these motors come with normal washers and anti-rotation washers.

The anti-rotation washers are usually fitted inside the triangle.

If you fit the anti-rotation washers on the outside of the triangle, you don't need spreading.

As Tony has said you can place the A/R washers outboard to reduce spreading of D/O's, A/R & washer placement can vary depending on whether a rotor needs to be lined up or the need to fit a T/A. For T/A I prefer to have mine sit nice and flat against the D/O so usually fitted in board on the RHS.

Aluminium 6061 has an ultimate tensile strength of at least 290 MPa (42,000 psi) and yield strength of at least 240 MPa (35,000 psi), Young's modulus : 68.9 GPa (9,990 ksi) Elongation at break: 12–25%.

The last bit (12% elongation before break) is an important point.

When you spread 5mm on a 20"wheel, the maximum elongation of the tie at the weld where the two branches of the rear triangle are tied together near the bottom bracket is roughly (5mm/130mm) * (100mm/250mm) = 1.5%. It's much more than spreading 5mm on a 26" or 700C frame. However, it's not a huge risk.

 

C'mon Whoosh that's a direct quote, I have it in front of me now. Do you know what factory those Apollo bike were fabricated in or what grade the tubing is because I don't. Being fair the whole build may go faultlessly but who knows.

You're a businessman Whoosh as I am (rtd) so have plenty of public liability insurance just in case things go wrong and I'm sure vfr has too, I wonder if Ben has . Who will be first to say ' Hang on now, I didn't tell him to do that! '.

All I'm saying is Safety First every time, conversions second.

Hi Ross,

 

when people do a conversion, they have issues like postioning the disc rotor, correct the chainline etc, people will have to re-arrange the washers for an optimal fit. The anti-rotation washers are 3mm thick and the normal washer 1mm but it's not always possible to move them outside so more often than not, they have to spread the rear triangle for about 5mm.

I have never known anyone damaging a rear triangle by spreading it that way (5mm). If you watch this video, you can see that the rear triangle is designed to flex a lot more than 5mm.

 

 

and same in this one in the other direction:

 

 

This one is tested to destruction (40mm compression)

 

Edited March 23, 20197 yr by Woosh

No need to bend the frame if your customer can live with one less gear.

 

On a Q100, the OLD spacing of 135mm is determined by a bushing and nut under the freewheel. Loosen the nut, file down the bushing, and use a thinner freewheel.

 

 

This pic is a Q128, but it works he same way,

If you are not buying the wheels spoked, the common practice of alternate in/out spokes doesn't work well. The in-facing spokes are bowed and don't touch at the cross like they should. I first did both wheels like this, but didn't like it. Tore them apart and respoked with all spokes facing out. Harder to do, but got rid of the bowing.

 

First try. The spokes are 1/4" apart where they cross.

 

Retry. All spokes face out. It's harder to do, as the 2nd set of spokes have to be persuaded to go around the first set.

Well, if it's 135mm as in Harrys photo, then I don't think it's going to be an issue. As I said I can spring the forks to 134 with my 65 year old arms. Maybe just maybe it will centralize as is, but I don't think a spacer or ar washer, on the inside, is going to be too much. I'll be buying built wheels.

 

There is a sticker on the frame that says it's 6061 custom tubing .

As to liability insurance - my neighbour will be appraised of the risks and the holes in my knowledge, then we'll make the decision together. I hate all this running scared of litigation that's killing so many aspects of life. I used to be in the St John ambulance brigade as a first aider, until it started to get that you couldn't actually touch some one who needed your help - in case they sued.

6061 is fairly standard stuff and to be fair shouldn't cause any problems if it's not over sprung.

The kit's been ordered from BMS. The battery's going to be ordered from Yosepower. He wants to go for big batteries and is keen on this one:

https://www.yosepower.com/en/product/Original-Rear-Battery-LG-Cell36V16Ah(592Wh)-Electric-Bicycle-Li-ion-Battery+3A-Charger-black-DIY-75.html

The spec states that the cells are LG(MH1), maximum current 20A, standard current 10A. Any body know about these cells, are they OK in conjunction with a S06S controller?

Seems good for £203.