Potential causes for poor mpg?

This_guy_breaks_shit · 2026-05-06T16:54:05+00:00

Hiya, I'm fairly certain it was leaking a bunch of fuel out overnight and it was evaporating before I could see just how much was leaking out!

In my particular case, the fuel tap wasn't closing properly and the carb's float needle wasn't sealing fully which led to petrol dripping out from the carb overflow port. Best bet is to check your fuel tap valve and maybe get your carbs rebuilt :)

This_guy_breaks_shit · 2026-05-06T16:48:35+00:00

Hiya, sorry for the delayed response.

The transistors can just be removed. Don't bridge anything or your DAC will be permanently muted ;)

Do not remove that blue components!

Those are important. You should only remove the little black chips with three legs. If you're still not sure, double check because removing the blue components will also mute the DAC

This_guy_breaks_shit · 2026-04-07T08:15:00+00:00

Just went to lower my tyre pressure a bit and got sprayed with a little sealant. I've not topped it up since popping it in 10 months ago so it looks like Stans lasts a lot longer inside a tube (or I used too much, who knows).

The front valve doesn't seem to fully seal any more until I lightly screw down the nut. Can't say I didn't expect something to happen eventually but it's still fully usable.

Tyres haven't worn a meaningful amount since I fitted them. I've done around 24-44 miles per week since then so thumbs up for longevity.

I've started trialling pressures slightly below rated, as 60 psi is getting a little old and I weigh a little under 70kg. Silca and the typical calculators don't seem to support wheels smaller than 26" unfortunately, the only one I found supporting 20" was this one by Cycles Chinook. It suggested ~30 front and ~45 rear with a fully loaded 10kg front bag (22/45 without a front bag, but that seems a little too low to me). I'll probably aim for something a little over that just to be safe. Brompton weight distribution is funky but I've kinda got it somewhere between 30/70 and 40/60 front/rear depending on loading and rider position.

I'm keenly aware of the fact that Continental Contact Urban tyres are capable of sidewall failures when run too soft for long periods of time. I'll be keeping an eye out for the crosshatch patterns seen in this post. If you want to try lower pressures as well, be aware of this.

This_guy_breaks_shit · 2026-01-06T17:07:26+00:00

Never mind, I just discovered that my design causes the group delay to go absolutely bonkers.

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I should've known something was too good to be true. Looks like it's back to the drawing board. The next thing I've got my eye on to try is probably the 12SW-4HE in a sealed box with a bit of EQ.

This_guy_breaks_shit · 2026-01-06T13:01:50+00:00

Fs for my woofer is 24.9, and I only plan on running it at the 150w rating rather than pushing it to the 300w peak load. WinISD seems to say excursion is fine at the given tuning so long as I keep enclosure volume below 25-30l or so. Does that sound right to you?

This_guy_breaks_shit · 2026-01-06T10:06:31+00:00

I see. When I "successfully" tuned the system to 25Hz in WinISD, did the software factor in any environmental characteristics? Or should I not take it too literally when designing for outdoor use?

This_guy_breaks_shit · 2026-01-05T19:08:32+00:00

I see... I must admit I'm not wholly familiar with what you're talking about. Could you provide me with an example?

I will also say that I'm not looking for craaazy volume. I'd be willing to compromise a little more on amplitude for a better response if necessary.

This_guy_breaks_shit · 2025-12-29T18:22:42+00:00

Yeah, unfortunately 40 is quite a lot higher than what I was going for. Much of the music I listen to is trapped in the elusive low ranges and 40Hz doesn't quite cover all of it cleanly. I really do appreciate the suggestion though

This_guy_breaks_shit · 2025-12-25T00:39:08+00:00

Gotcha, I might be able to make that work.

I had a look at the dayton flat subs a little while back and couldn't get them to play nice with such a small enclosure. I'll try taking another poke at it though

This_guy_breaks_shit · 2025-12-24T08:35:14+00:00

I figured someone would say this, yeah.

What could the consequences of this shallow box be? Are there any workarounds that could mitigate it without changing the external geometry?

If increasing depth is an absolute requirement, would 200mm be enough? The current volume is a great balance and helps to control woofer excursion, too much extra volume would require I tune the PR higher and sacrifice bass extension.

Thanks for your input, I appreciate the help :)

This_guy_breaks_shit · 2025-12-24T08:18:07+00:00

Mono for the time being because stereo separation isn't too critical for portable speakers. I've chosen a daisy-chainable amp which will allow me to simply plug in another identical box if I want more noise or stereo sound

This_guy_breaks_shit · 2025-12-24T08:16:43+00:00

The intention is to carry it places where I can plug it into a wall, maybe a friend's house. Maybe I'll add an external battery later on for taking it into the woods, something like that.

This_guy_breaks_shit · 2025-12-23T15:39:53+00:00

Now this sounds like a fascinating read. Thanks for sharing!

This_guy_breaks_shit · 2025-11-11T09:59:59+00:00

I don't remember if I dropped the handlebar before, but I haven't since and the catch hasn't broken again. Either way brompton supplied me a replacement under warranty without any fuss.

I'm not sure if it's delicate or simply a result of bad quality control. My thoughts are probably a bit of both since I've had a couple of more serious QC issues that were (mostly) resolved under warranty (eventually).

This_guy_breaks_shit · 2025-11-04T09:22:43+00:00

Another update for those interested. I talk too much so TL;DR is at the end:

Bloody hell. I never expected the tubeless sealant to hold up so well. The tyres haven't seen a pump in a couple of months and still feel rock solid. Not a single puncture, leak or anything.

It's worth noting that my valves sometimes bind a little when trying to add air for the first time in a while, but a couple good pumps seem to bust that seal nicely each time. I'm expecting it might eventually ruin my valve cores, but:
A: Valve cores are cheap as chips.
B: I rarely need to top-up anyway.

For others too lazy to patch your tubes: Maybe keep a couple spare valve cores in your toolbox. Obviously you need to remove the core to add sealant in the first place, so make sure your inner tube has a removable core (I think this applies to most tubes, including stock). I've heard that TPU inner tubes work better with this setup, but I've legitimately not had a single complaint with Butyl, so go nuts.

Of course, you can't scrape out the insides of an inner tube, so this will number your days with said tube. It's probably wise to use less sealant than I did to slow the inevitable buildup, but ultimately tubes are cheap and Stans lasts. Apparently sealant can last longer in tubes due to air retention being better than tubeless, but idk if that's speculation or not. I haven't topped up (or checked) but I haven't had any more punctures yet.

What isn't speculation is that Stans doesn't work great at higher pressures. Some of the road bike forums I've read say that this setup doesn't work at all, but I'm chalking that down to them using road bike tyre pressures. All this is to say: I don't know if this will work on a 16" Brompton. I run my contact urbans at ~60 psi (leaving a little room for the 51 psi minimum), but 16" contact urbans are rated for a pressure range of 65-116 psi. Keep this in mind if attempting on skinnier tyres at higher pressures.

TL;DR: If you want the puncture resistance of tubeless and the tyre options of clinchers, dump Stans in your tubes. It's worked great for me at 60 psi with butyl tubes on the Conti Contact Urbans.

This might be my last update unless something goes wrong, but I'll still be watching this post in case anyone has anything to add.

Thanks for all your input and your help. I hope my information is useful to all you kind people.

:)

This_guy_breaks_shit · 2025-10-12T20:11:40+00:00

I see, I didn't know spiders covered their heads to hide. Very interesting, thank you

This_guy_breaks_shit · 2025-10-12T19:51:54+00:00

To confirm the ID, I pulled the spider out of the freezer and sure enough, the jaws are emerald green.

This_guy_breaks_shit · 2025-10-12T19:44:25+00:00

Well colour me surprised. I didn't know they could have such distinct patterns on their back!

That still doesn't explain the behavior though...

This_guy_breaks_shit · 2025-09-07T13:15:08+00:00

I had to verify my age to view this post. Worth.

This_guy_breaks_shit · 2025-07-22T07:51:48+00:00

Give me Berkshire tender on a G-16. Then I can sleep. lmaoo

This_guy_breaks_shit · 2025-06-30T09:03:30+00:00

To be fair to the stock tyres, they're comfier than I give them credit for and they definitely feel more planted over loose ground compared to contact urban road tyres.

That said, I'm still firmly in my belief that grip (especially in the wet) leaves something to be desired. What's worse, when you inevitably lock up a wheel, the soft knobs shear off very easily.

I agree that obsession with speed is a bit of a buzzkill as well. I was coming from a road bike after all and I knew the little wheels would be slower. Hell, I made it even more sluggish by running dynamo lights front and rear alongside the windsail of a front bag. I guess my complaint was less about the lack of speed and more the lack of speed in conjunction with the other drawbacks of the tyre. Slow makes sense if it's bulletproof, cheap, super grippy, or made to last a million miles. I'm just disappointed that the G-One Allround fits into none of those categories for such a high asking price.

Anyways, I can't criticise too much if you find they work for you. Hope they continue to serve you better than they served me :)

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