Vintage Peugeot Carbolite 103 - strong enough for a conversion?

[MaximilianMM]

Hi there,

I'm considering a conversion on an old Peugeot Carbolite 103 frame.

Someone on another forum says:

'A 1982 Peugeot catalog had a vague description of Carbolite 103, calling it "a special, thin-walled tubing made from a composition in carbon steel unique to Peugeot. This tubing combines strength and resilience and produces the unusual durability of our bicycles."

I've never seen detailed specifications for Carbolite 103, but have seen speculation (without any specific references) that it is similar to AISI 1030 carbon steel.'

The bike is in decent condition.

Does anyone have any opinions on whether it could likely handle an ebike conversion kit (with torque arms of course)?

Thanks in advance.

 

[Chalo]

"Carbolite" is marketing bullshit for mild steel-- the cheapest material used in bicycle frames.

A bike like that should be fine for a 250W to 350W hub motor conversion. The rear spacing won't be compatible with rear hub motors, so I'd use a front motor rather than bend the frame wider.

It's an old, kind of flimsy bike that works adequately for sub-20mph speed. Don't ask more from it than it wants to give.

 

[LewTwo]

.... marketing bullshit ....

That seems to be the most abundant material on the planet :?

 

[MaximilianMM]

"Carbolite" is marketing bullshit for mild steel-- the cheapest material used in bicycle frames.

A bike like that should be fine for a 250W to 350W hub motor conversion. The rear spacing won't be compatible with rear hub motors, so I'd use a front motor rather than bend the frame wider.

It's an old, kind of flimsy bike that works adequately for sub-20mph speed. Don't ask more from it than it wants to give.

Thanks for the advice. I think I'll look for something stronger.

Do you think a solid old Reynolds 531 or similar would be good for a 1000w motor on the front?

One other question - I have a 48v battery already which I'd like to use on this. If I do decide to go with a smaller motor (i.e. 250W 36v) would the controller/motor be compatible with that battery?

 

[Chalo]

Do you think a solid old Reynolds 531 or similar would be good for a 1000w motor on the front?

One other question - I have a 48v battery already which I'd like to use on this. If I do decide to go with a smaller motor (i.e. 250W 36v) would the controller/motor be compatible with that battery?

I think any old pre-'85 road bike will be a little floppy once you load it with the extra weight of equipment, and motor thrust in unintended locations. The lighter, nicer ones might or might not be stronger, but they will be even more flexible than the cheap ones.

Generally speaking, you want to build an e-bike on a chonkier donor bike than you'd prefer if you were running on pedal power only.

Typically you can run a 36V controller on 48V, but the low voltage cutoff won't work as intended. Motors are cool with pretty much any voltage you want to send them, though their unloaded speed will increase in proportion to voltage.

 

[MaximilianMM]

Do you think a solid old Reynolds 531 or similar would be good for a 1000w motor on the front?

One other question - I have a 48v battery already which I'd like to use on this. If I do decide to go with a smaller motor (i.e. 250W 36v) would the controller/motor be compatible with that battery?

I think any old pre-'85 road bike will be a little floppy once you load it with the extra weight of equipment, and motor thrust in unintended locations. The lighter, nicer ones might or might not be stronger, but they will be even more flexible than the cheap ones.

Generally speaking, you want to build an e-bike on a chonkier donor bike than you'd prefer if you were running on pedal power only.

Typically you can run a 36V controller on 48V, but the low voltage cutoff won't work as intended. Motors are cool with pretty much any voltage you want to send them, though their unloaded speed will increase in proportion to voltage.

Thanks. Is it bad if they're more flexible, yet stronger? Sorry if that's a stupid question.

I guess a chromoly steel would be ideal. I see a lot of 'hi-tensile' steel, which I understand is less strong than chromoly, but not sure if it's an upgrade on Carbolite.

 

[MaximilianMM]

Update - I got a cro mo steel frame for £40. I think this should be up to the job. https://ibb.co/3hXcKhY
https://ibb.co/bBL4bwY

 

[Chalo]

I think any old pre-'85 road bike will be a little floppy once you load it with the extra weight of equipment, and motor thrust in unintended locations. The lighter, nicer ones might or might not be stronger, but they will be even more flexible than the cheap ones.

Thanks. Is it bad if they're more flexible, yet stronger? Sorry if that's a stupid question.

I guess a chromoly steel would be ideal. I see a lot of 'hi-tensile' steel, which I understand is less strong than chromoly, but not sure if it's an upgrade on Carbolite.

Flexibility in a loaded bike is not likely a problem for the bike, but it can be detrimental to handling and composure on the road. Before I converted an old skinny tubed bike, I'd ballast it up to simulate the weight and location of battery and other gear, and ride it around to see if I still liked it. I'd do some tight U-turns and fast downhill curves to try to make it misbehave.

"Hi tensile" is another bike industry euphemism for mild steel. Carbolite and hi-ten are the same. One advantage to a bike made of mild steel is that it will use thicker walled tubing than a chromoly or other high strength alloy steel frame with the same dimensions, so it will be stiffer for that reason.

It's more structurally efficient to use larger tube diameters to increase frame stiffness, but increased wall thickness also does that job (though with greater weight). Witness the old Chicago Schwinns that had tiny 1" main tubes, but were still quite stiff because there was so much steel in them. Those would make pretty good e-bike conversions compared to most other frames of the same time period.

 

[999zip999]

My old giant comoly MTB has 40,000 miles in 9 years. Yes comoly steel cheap old 1992 bike. No suppession. But a thud buster seat post.

 

[MaximilianMM]

I think any old pre-'85 road bike will be a little floppy once you load it with the extra weight of equipment, and motor thrust in unintended locations. The lighter, nicer ones might or might not be stronger, but they will be even more flexible than the cheap ones.

Thanks. Is it bad if they're more flexible, yet stronger? Sorry if that's a stupid question.

I guess a chromoly steel would be ideal. I see a lot of 'hi-tensile' steel, which I understand is less strong than chromoly, but not sure if it's an upgrade on Carbolite.

Flexibility in a loaded bike is not likely a problem for the bike, but it can be detrimental to handling and composure on the road. Before I converted an old skinny tubed bike, I'd ballast it up to simulate the weight and location of battery and other gear, and ride it around to see if I still liked it. I'd do some tight U-turns and fast downhill curves to try to make it misbehave.

"Hi tensile" is another bike industry euphemism for mild steel. Carbolite and hi-ten are the same. One advantage to a bike made of mild steel is that it will use thicker walled tubing than a chromoly or other high strength alloy steel frame with the same dimensions, so it will be stiffer for that reason.

It's more structurally efficient to use larger tube diameters to increase frame stiffness, but increased wall thickness also does that job (though with greater weight). Witness the old Chicago Schwinns that had tiny 1" main tubes, but were still quite stiff because there was so much steel in them. Those would make pretty good e-bike conversions compared to most other frames of the same time period.

Thanks. So it sounds like it's somewhat a trade-off between handling and strength in some cases. Good advice. I've got the battery on the back and the motor on the front so maybe they will balance eachother out a bit.