130Kg on a 2012 Brompton

[Jwan]

Hi all

I weight 130Kg, I have a Brompton from my younger days. It was bought in 2012.

I want to start cycling into work, can my Brompton handle my weight?

Thank you.

[Vorpal]

Yes. Likely stuff will wear out more quickly, but I don't see any reason not to. Brompton suggest that it is designed for up 110 kg, but that is for warranty & covering their backsides purposes.

Fit the widest tyres you can, and keep the tyres pumped to at or near the maximum pressure.

[Jwan]

Thanks, Vorpal, I'll take the bike out of the basement, give the chain a good clean and lubricate it, pump the tyres, check the breaks and give it a go. I'll report back tomorrow.

[simonhill]

Look on the bright side, a few days cycling and you'll probably be down to 110kgs.

I'd be careful with the saddle, that may be a weak point, especially on an older bike. Check where it fixes to seat post and the rails to the saddle.

Good luck and enjoy.

[Brucey]

I would recommend that you fit new tyres sooner rather than later; the fabric in old tyres may already be rotted and if the rubber in the tyres is cracked at all (and it normally is, in neglected bikes), then the fabric in the tyres will likely soon rot even if it isn't rotted already.

cheers

[horizon]

It's a good question. I'm 74 kg but I carry (at the last count last weekend) 30 kg camping (appreciated by Mrs Horizon who carries about 12 kg ). But that brings me up to 104 kg. I expect my regular bikes to carry that much but will my aluminium folder? It too has a weight limit of 110 kg but I don't trust it so much.

[alexnharvey]

I think that in general folding bikes are inherently compromised and often weaker than full size ones. Maybe this is influenced by a colleague and several acquaintances breaking their Dahons and injuring themselves recently. Maybe the same is not true for a steel Brompton.

Nevertheless, I think if you are not needing the folding function at the moment you and the bike might be more comfortable consciously uncoupled for the time being.

[Cyril Haearn]

I think that in general folding bikes are inherently compromised and often weaker than full size ones. Maybe this is influenced by a colleague and several acquaintances breaking their Dahons and injuring themselves recently. Maybe the same is not true for a steel Brompton.

Nevertheless, I think if you are not needing the folding function at the moment you and the bike might be more comfortable consciously uncoupled for the time being.

+1
130 kg is a lot, even if you try to ride gently you strain the machine more, the material fatigues
I like to keep well inside limits
Try googling these fora, there was a thread (or more than one?) about bikes for big/heavy people
If I were big and very tall I would get an enormous frame, 26" maybe, hardly anyone could ride/steal it

[Brucey]

the bike doesn't know how much weight is being carried; the bike sees stress and dead weight is just one source of stress. Stress comes from (in no particular order);

- the weight of the rider + luggage
- how rough the road is
- how hard you push on the pedals
- how much you wrestle with the handlebars

All these stresses add together in some parts of the bike and this can create a very destructive condition. The place where most folding bikes are most vulnerable is in the middle of the spine, particularly where the hinge plates are welded (or brazed, or bronze-welded) to the spine of the frame. The first three things on the list above are bad enough, but if you wrestle with the handlebars, you can impose a huge torsional stress in the spine of the frame, because you have two long levers (the seat post and the handlebars) with which you can wind it up. If this happens even a light rider can soon break a folding bike.

Bromptons are bronze-welded together and resist this damage fairly well, considering, but typical welded aluminium frame spines are very much prone to breakage at this point.

This problem is so severe that with (aluminium) Dahons and the like, I would say it is only a matter of time until they break if they are 'ridden with enthusiasm' for any significant distance by a 'handlebar wrestler'.

Brompton frame failure can happen but it is very much rarer. If a Brompton frame does break, it is unlikely to snap into two pieces with no warning; more likely the whole bike will bend in the middle once the crack reaches a certain size, then you will notice and stop riding it.

Bromptons are fitted with quite a few 'lifed' light alloy parts that Brompton suggest should be replaced at intervals anyway. IIRC these include the handlebars, stem, seat post, crankset etc, and Brompton say you ought to replace these at 5000 mile intervals (in a backside-covering way); few Brompton riders ever ride that far and of those that do, very few take this recommendation seriously. However if you impose additional stresses on the bike the service interval of these parts should be shortened.

So if you are big, strong, pedal slowly (a.k.a. 'mashing the pedals') and wrestle with the handlebars as you ride down rough roads you should be worried. On the other hand if you are big, unfit, weak, spin the pedals quickly and don't wrestle with the handlebars as you ride on smooth roads, you have less reason to be concerned.

cheers

[horizon]

Both my folders (a Dahon and a Tern) have rear and front luggage braze-ons and both companies sell their own branded front and rear pannier racks. Both companies (AFAIK, I haven't checked) sell touring versions of their folders complete with racks. I really don't know whether they genuinely believe their bikes are up to it or are just selling a fantasy. I know I can load either folder for camping (the facility is there) and I think they would handle well but I simply don't trust the frame for all the reasons you state.

https://www.ternbicycles.com/my/bikes/471/verge-s27h

PS The fork is steel.

[simonhill]

I take Brucey's point(s), particularly the heavy handed twisting (wrenching) style, but think that rider weight and luggage/dead weight should be treated as separate loads. Rider's weight can be juggled over bumps, etc to mitigate the shock, luggage weight can't.

Nonetheless, I have always had a thing about 'heavy' people and 'light' people. Nothing to do with their actual weight, but how they use it. A heavy rider will stamp on the pedals in a high gear wrenching on the handlebars. A light rider will start off gently in a low gear and pick up speed, etc, etc. This differentiation applies to all sorts of things - watch how different people go up stairs or push the buttons in a lift.

I am a light person which means most things I own never wear out.

[horizon]

Although the luggage can't be lifted over the bumps, I had always assumed that the fact that the rider/luggage weight was distributed was an advantage, particularly the front panniers as they are down low. On this reckoning, my 75 + 30 is better than one person's own weight of 105 but of course I don't know if that is true.

[Brucey]

probably better for the frame, most of the time, but worse for the wheels for sure....

cheers

[horizon]

probably better for the frame, most of the time, but worse for the wheels for sure....

cheers

Well the wheels are smaller and therefore stronger? Spoke count is 28/20.

[Vorpal]

the bike doesn't know how much weight is being carried; the bike sees stress and dead weight is just one source of stress. Stress comes from (in no particular order);
<snip>
So if you are big, strong, pedal slowly (a.k.a. 'mashing the pedals') and wrestle with the handlebars as you ride down rough roads you should be worried. On the other hand if you are big, unfit, weak, spin the pedals quickly and don't wrestle with the handlebars as you ride on smooth roads, you have less reason to be concerned.

cheers

While I agree with Brucey's post, I think that he has framed it (see what I did there ) quite negatively. As discussed previously on this forum, aluminium has no fatigue limit, and will eventually fail. We don't know whether this will be in 5 years or 20, becuae it depends on very many things, but for a bike that is regularly heavily loaded, it will be sooner than for one that is lightly loaded.

There is no reason for a well-designed and correctly built steel frame to fail until it is significantly damaged by rust, even if the load it is theoretically designed for is somewhat exceeded.