BMW R1200RT/R1250RT Forum

I’m sure I saw a recording of installing a Stebel into an RT, but I can’t find it, thought i’d saved it but not!!
Could anyone point me in the right direction please.

I have a Fiamm Mini Blaster on my 1200RT and have just installed one on my other half's MT07.  Being relatively small I was able to mount them in the same place as the original horn in both cases.  I did suggest to Kate that she tries it out a few times so that, when she uses it for real, she doesn't startle herself. 

Be careful with that.  I fitted one and it chafed on the brake hose

Hmmm so the nautilus still needs a relay, even on RTs with canbus?

Old-Git wrote: Hmmm so the nautilus still needs a relay, even on RTs with canbus?

ESPECIALLY with CanBus.
The CanBus system protects the wiring from overload. This means that the wiring can be as light a gauge (thickness) as possible (to save weight).
You go and hang a high current drawing horn on the bike and it is a recipe for burning out the wiring loom. So that is why we fit heavy gauge wire through a relay to feed the Amp hungry horn, but we trigger (switch) the relay with the low current signal from the horn button.

I've retreated to a Stebel magnum (no compressor) straight through the Canbus.  Had the same fitted to my K1300GT and it worked okay and is pretty loud.  The Stebel Nautilus was rubbing against the brake and ABS lines especially on left turns.

I heard that the Nautilus Stebel Nautilus will be an MOT fail because the power from the switch doesn`t directly drive the horn, it switches the relay which in turn drives the air compressor, which then produces the sound. Has anyone heard of this potential MOT fail?  It was a guy at the local bike workshop who told me, I guess he should know what he was talking about. I`ve already bought the Stebel Nautilus but I`m hesitating before fitting it. I donn`t want the faff of having to reconnect the original beeper for the MOT.

[size=78%]  [/size][size=14px]The regs say a horn must be " continuous, uniform and not strident " on a vehicle "first used on or after 1.8.1973"[/size]
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[size=14px]    No mention on What source the horn must use for it to operate,  some commercial vehicle fit air operated horns as standard, so no a vehicle fitted with an air operated horn will not fail the mot as long as it complies with the statement above.[/size]

BBT600 wrote: I heard that the Nautilus Stebel Nautilus will be an MOT fail because the power from the switch doesn`t directly drive the horn, it switches the relay which in turn drives the air compressor, which then produces the sound. Has anyone heard of this potential MOT fail?  It was a guy at the local bike workshop who told me, I guess he should know what he was talking about. I`ve already bought the Stebel Nautilus but I`m hesitating before fitting it. I donn`t want the faff of having to reconnect the original beeper for the MOT.

That is ABSOLUTE rubbish. Many horns are driven through relays because the current required to drive bigger horns would destroy the lightweight contracts of the vehicle switching system.
Moreover, on many modern vehicles  the horns are not driven directly from the switch, they are controlled by the relevant Bus system (such as CanBus). The switches often just communicate with the controller and the controller fires the horn.


Even the old R1100 and 1150RT as standard fed the power to the horns through relays.


So we can put that one to bed.

Thanks for confirming re relay bandytales. That's that horn out for me, I fitted one years ago when I was commuting through London daily, I always "felt" that there was a short delay between pressing the button and the horn sounding. That's when I started wearing flip up helmets, I always thought I could shout quicker than the horn would respond. Always a possibility that it was my crap wiring I guess, but still not for me.Gonna go with a stebel magnum, however a quick search shows the low note horn being advertised as 112 and 136db - I assume the latter is not correct? Sprintgull did you get the low or high note horn for your bikes?TaNick

Hi Nick
The Stebel is low note and is pretty loud.  Okay it might not make errant pedestrians part company with their shoes, but much more loud than the standard tinny beeper.  It's a shame the Nautilus didn't work out but there was a definite rub between the brake hose and the bottom of the horn.  Also it was hesitant to sound when I first fitted it, then the bugger stuck on (that was fun, the only way to shut it up was take the seat off and pull the fuse out).  New relay sorted it, the old one was badly burned.  Good luck.

Hi I had a senior moment I had forgotten that I have already installed a Denali soundbomb mini (low range). I was thinking of upgrading due to this moment last week https://youtu.be/400uwjWPB-g I would have liked something louder in this situation..... camera is under the headlights so close to the horn. Sorry about the size of the video will look for an app to make it bigger.

Sprintgull wrote: I've retreated to a Stebel magnum (no compressor) straight through the Canbus.  Had the same fitted to my K1300GT and it worked okay and is pretty loud.  The Stebel Nautilus was rubbing against the brake and ABS lines especially on left turns.

Yes, I also fitted a Stebel Magnum on my RT, utilising a Nippy Norman’s purchased CANBUS wiring adapter to interface with the OEM horn to bike connector. No problems, and a decent louder horn to replace that pathetic OEM excuse for a horn!

A slightly better video clip https://youtu.be/VL8sgxHtGZE