A mini – mini bikepacking stove review (Bearbones 8g stove)

http://bearbonesbikepacking.co.uk/pages/contact.html#stoves

Bought one of these and it arrived today so just been playing around with it in the kitchen and thought I’d post up my musings after the alpkit stove thread earlier in the week.

Out the box:
It’s designed to be used with a 450ml ti-mug, I’ve got a 750ml mug as I figure it’s really 450ml+some stirring room. As a result the enclosed windshield template doesn’t quite fit around it.*

The little bottle weighs 14g, 5g more than the stove! And holds about 80g of meths. The stove burnt 11g of meths to boil 450ml water, so if you were splitting that between noodles and tea you’d have enough for about 7 meals (noodle brand and tea strength dependent).

Windshield:
Made a simple one from a foil platter rolled flat, folded the long sides in to make a rectangle, cut out some semi circles around the top, and a bigger gap for the cup handles, then cut 6 slits in the bottom and folded in between every other one to make some air inlets, folded in between the semi circles at the top to spring it away from the cup slightly. All held together by interlocking slits at the join.

I can’t see it being very stable on anything other than a flat solid bit of ground, and with the burner that low it would be dangerous on dry ground in a hot summer meaning you really would have to cook on top of a rock or something. So the windshield contributes quite lot to the stability of the setup, just make sure the pot is definitely resting on the top of the stove to seal it.

20141004_134229 by thisisnotaspoon[/url], on Flickr

Filled with meths it takes about 30s to bloom. Without a cup on top it kicks out a serious amount of heat (and it’ll burn a stovefull of meths in no time at all), so I found the best way was to fit the windsheild to the cup then put the whole thing on the stove then push the cup down through the windshield so it rested on the stove. Putting the windshield down first just channels the flames nicely straight onto your hand!

20141004_134241 by thisisnotaspoon[/url], on Flickr

Boiling stuff:
With 450ml of tap water in the pot it took 7min30 to boil (but only just), it’ll boil 450ml and not a drop more. But unlike a trangia stove it cooled down quickly enough that putting a drop more fuel in wasn’t an issue to keep it boiling if you had something to cook, but for most camping meals I’d take it off the stove to cook in it’s own heat anyway, so in reality it would probably be enough fuel to boil 300ml of water, add supernoodles, and bring back to the boil. Otherwise it just about makes 2 cups of tea.

The science bit:
LHV of ethanol = 28.8 kJ/g (11g = 316.8 kJ)
Sensible heat capacity of water = 4.181 j/gC (450g * 80C = 150.5)
Efficiency = 47% Dunno how that compares to other stoves, but does include fuel ‘wasted’ while it’s not blooming etc.

20141004_134300 by thisisnotaspoon[/url], on Flickr

Conclusion:
Great for re-hydrating noodles and making tea on an overnight adventure, probably rubbish for frying bacon or cooking for more than one person (but you could carry 4 and still be under the weight of a conventional stove). If I was planning a multi day trip it would be this boiling stuff in the mug and a trangia/coke can style burner for more elaborate meals (i.e. bacon).

*that’s actually just an excuse, I really just forgot how big my pot was.

It’s the Bearbones stove with the fuel-line that interests me the most – no more wasted fuel or running out before something’s ready.

That does look cool, but unless you just want to boil a lot of water I didn’t really see what it was useful for. If I was going out with a group then splitting a bigger stove between the group wouldn’t be an issue, a trangia between 4 people is probably no heavier than 4x mugs, stoves, windshields, etc.

I have the larger version of that stove, really rate it. Better than a pop-can DIY job. I made a couple of rougher versions of the 8g, they work well but the jet holes need refining still. Stuart seems to have got all that pretty well figured out.

good to see some more rigorous scientific research 🙂

So from my data here

For the Pocket Rocket burning off Primus gas mix:
LHV Propane/Butane mix c. 46kJ/g
10g of fuel is 460kJ
Sensible* heat capacity of water = 4.181 j/gC x 500 x 80 = 167 Kj
so only 36% efficient, but it did it in 3m30s

* I like that 😉

There’s a new stove due shortly that has the ability to ‘simmer’ so might be ideal for knocking up the bacon, etc 😉

Wasn’t so much the lack of simmer that would prevent bacon being cooked, that’d be fine full blast, it’s the way it needs the pan on top to create a seal on the stove and stop the meths just burning from the pool in the center. With no pan on top it burns a stove of meths in under a minute (not timed it but it’s really quick). Whereas the coke can stoves create that seal by other means, e.g. a small fill hole covered by a coin.

[edit] just realized you are ‘bearbones’, so you probably already knew that! When’s the ‘bacon cooker’ coming out?

just realized you are ‘bearbones’, so you probably already knew that! When’s the ‘bacon cooker’ coming out?

Hopefully a week to 10 days. It’s a centre burner design so doesn’t require a pot / pan to sit on top. In simmer mode 15ml of fuel will burn for roughly 25 minutes.

Cool, I’ll keep an eye out for that.

Does/has anyone tried ispropyl alcohol in a meths stove? In theory it’s got 10% more energy per gram.

After soem further experimentation I’ve figured out that:

1) Isopropanol (IPA) does indeed burn, but is very sooty, and doesn’t seem to be any more powerfull.

2) This stove does not like overfilling (either with water or meths).

There’s a noteable increace in noise as the water gets warm so I guess when it’s cold it chills th meths slightly and supresses it’s boiling/vapourisation. Once the water temp gets above the boiling poinf of the meths it really gets going. As such, boiling 250-300ml is much quicker (4.30-5min) than boiling 450ml. And the stove tends to use all it’s fuel regardless (i.e. a stove of fuel boils a pot of water with little spare, regardless of the ammount of water below about 400ml)

Overfilling with meths reults in liquid being pushed out of the holes (flareing). At first I thought this would be of negligable importance, the fire kept going, but I found that not getting evey last drop into the stove to start with, and lifting the cup slightly to release pressure/excess fuel when it flared to allow the stove to settle down to a normal bloom.

From a physics standpoint I think I can explain the lack of increace in power from IPA and additional meths. IPA is 3 carbon atoms, therefore requires more oxygen to combust. As combustion doesnt happen in one step the chain is decomposed and the likleyhood of oxygen reaching the last carbon atom beofe it leaves the flame is reduced, so the isn no increace in power as the combustion is incomplete.

Ethanol (meths) is only 2 carbon atoms, so will burn cleanly almost regardless of the fuel/air mixture. Hence it’s pupularity in camp stoves as there’s no valves/mixing required. Overfilling with meths reuslts in a large fuel excess in the air under the pot, which doesn’t burn, even though there’s not a sooty/yellow flame. So theres an increace in fuel consumption for no increace in power (it is acualy dropping IMO). The flareing seems to be self sustaing and doesn’t drop down to a normal bloom untill later on, so by lifting up the mug to allow the excess fuel to flash off and the stove to reach a normal bloom. Basicly you waste a little fuel to save a lot.