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M Part MegaHorn



Does the job, but compared with the friendly ching of a bell, it's a bit unpleasant
Easy to fit and use
Decent water resistance
Unpleasant noise
Not rechargeable
Battery not included

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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The M Part MegaHorn makes a loud trilling noise to alert other road and path users of your presence; it gets people's attention but I'm not sure it's better than the classic, friendly cha-ching of a bike bell when it comes to the balance between 'alert' and 'alarmed'.

The MegaHorn is dead easy to use. Press the button (it has a remote) and a din like a dalek singing in the shower ensues, causing folks to look round wondering what the hell that noise is. On the one hand, that's good: people know you're there. On the other, it's not a sound you'd associate with a bike and rider so it confuses some people.

2021 M Part Megahorn - remote on bars 1.jpg

You could make the case that a standard bike bell is sometimes too polite, but at least when people hear it they're expecting a bike. The MegaHorn's electronic warble is borderline obnoxious and is not going to endear you to the kind of person who thinks a bell is a signal of entitlement.

Still, if you ride on the kind of crowded city streets where pedestrians tend to just step out, it does the job (though I think in those situations it's better to ride well away from the kerb so you've room to take evasive action; it's your responsibility not to ride into people, both ethically and according to the recent changes to the Highway Code).

Reliability & water resistance

Some users report that their MegaHorns just stopped working after a short while. I've had no problems.

Thinking that water might have been the cause for those people, I doused the MegaHorn with a water spray to simulate a rain shower and it still worked, so it seems to live up to the claim of being water resistant. M Part doesn't specify an ingress protection rating (that's the code like 'IPX6' you see on many water-resistant electronic devices), so we don't know just how water resistant it's supposed to be.

I then left it under 10cm of water for 10 minutes and after that it still worked, so I'm content to say that it's as water resistant as it's reasonable to expect, and maybe more so given there's no sealing round the battery case and there are gert holes up front to let the noise out.

2021 M Part Megahorn - battery housing.jpg

It runs off a 9V battery but you have to supply your own, which seems a bit stingy.

User reviews of the MegaHorn reveal an extra use case that hadn't occurred to me: getting a motorbike without a horn through its MOT. Apparently some enduro and motocross bikes don't have horns; strapping on a MegaHorn fulfils the legal requirement at MOT time.

Value and conclusion

Price-wise, it's in the ballpark for decent-quality noisemakers. It's a bit cheaper than the £29.99 Hornit dB140 (full review of that to come), so decent value, if more expensive than most of the electronic noisemakers you can find on eBay and Amazon. There's a mini version of the MegaHorn too, for around a tenner less, with a 70dB output rather than the Mega's 105dB.

> Buyer’s Guide: 6 of the best bicycle bells

The MegaHorn certainly succeeds in its mission to provide an 'audible presence', I'm just not convinced it's the right sort of presence. If you really want to make pedestrians jump out of their skins, you might as well strap an air horn to your bike. A schoolmate blew one at me from his bike when I was a teenager; I've never got across a road quicker. You can even get hand-pumped horns that don't need batteries or gas canisters. They probably won't get your old KTM through its MOT, though.

Who should buy the M Part MegaHorn? Anyone who rides busy city streets, wants to alert inattentive road users of their presence and finds a standard bike bell just isn't loud and piercing enough. Just be prepared for a bit of confusion and possible narkiness.


Does the job, but compared with the friendly ching of a bell, it's a bit unpleasant test report

Make and model: M Part Megahorn

Size tested: n/a

Tell us what the product is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

It's for making lots of noise to alert other road users of your presence.

M Part says:

Super loud and effective electronic horn

Great for town and city riding where audible presence is required

105 dB volume at 1 yard

Fits all handlebar types and sizes and is easy to fit

Remote switch means you don't have to take your hands off the bars in an emergency to activate the horn

Water resistant construction for year round use

Takes PP3 9 volt battery (not included)

Rate the product for quality of construction:
Rate the product for performance:

Does what it says on the tin: makes lots of noise.

Rate the product for value:

It's in the ballpark for decent-quality noisemakers.

Tell us what you particularly liked about the product

Ease of use.

Tell us what you particularly disliked about the product

Can't say I'm fond of the noise it makes.

How does the price compare to that of similar products in the market, including ones recently tested on

It's a bit cheaper than the Hornit dB140, more expensive than most of the electronic noisemakers you can find on eBay and Amazon.

Did you enjoy using the product? Not especially.

Would you consider buying the product? No, I'd use a bell.

Would you recommend the product to a friend? Only if they were willing to take the risk of being seen as a bit loutish.

Use this box to explain your overall score

The M Part MegaHorn does what it's supposed to do, I'm just not sure the way it does it is very pleasant. Cycling should be fun, even if you're just zipping through town, and the megaHorn's sound just isn't much fun.

Overall rating: 6/10

About the tester

Age: 55  Height: 5ft 11in  Weight: 100kg

I usually ride: Scapin Style  My best bike is:

I've been riding for: Over 20 years  I ride: Most days  I would class myself as: Expert

I regularly do the following types of riding: commuting, touring, club rides, general fitness riding, mtb,

John has been writing about bikes and cycling for over 30 years since discovering that people were mug enough to pay him for it rather than expecting him to do an honest day's work.

He was heavily involved in the mountain bike boom of the late 1980s as a racer, team manager and race promoter, and that led to writing for Mountain Biking UK magazine shortly after its inception. He got the gig by phoning up the editor and telling him the magazine was rubbish and he could do better. Rather than telling him to get lost, MBUK editor Tym Manley called John’s bluff and the rest is history.

Since then he has worked on MTB Pro magazine and was editor of Maximum Mountain Bike and Australian Mountain Bike magazines, before switching to the web in 2000 to work for Along with founder Tony Farrelly, John was on the launch team for and subsequently became editor in chief of Future Publishing’s group of cycling magazines and websites, including Cycling Plus, MBUK, What Mountain Bike and Procycling.

John has also written for Cyclist magazine, edited the BikeMagic website and was founding editor of before handing over to someone far more representative of the site's main audience.

He joined in 2013. He lives in Cambridge where the lack of hills is more than made up for by the headwinds.

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