Rider to Rider Communication

I bought an adventure bike to explore off-road. I also bought a helmet intercom system from Sena (actually mine is branded HJC but it made by Sena, it is an HJC 10B). I rode with some friends that also have helmet intercoms. This is really great, pretty much a necessity once you have had it. There is no going back. You can hold a conversation while riding. The front person can also warn the people behind of upcoming obstacles, vehicles, hazards, etc. You can also discuss where you want to ride, what turns to take, do you want to stop, etc.

The two leading helmet communications makers are Sena and Cardo. These 2 both have mesh systems which allows the communications to use multiple riders to relay messages across the group. This also allows for larger groups of riders to all communicate at the same time. These 2 mesh systems are not compatible though (although Cardo now offers a bridge feature to connect them). This intercom approach is great for street riders who ride close together (less than a mile with clear view). However, off-road the intercom approach has some issues. Off-road we have things like dust, gravel, and rocks getting kicked up by the tires, narrow trails, and other issues that make us ride much farther apart. We also have hills, canyons, mountains, and other obstacles that interrupt the communications. If the person in the back drops their bike, communication is lost pretty fast as the other riders increase the distance. Just when you need it most you lose communications. Mesh helps some as it daisy chains all the riders but you can still break the chain at any time.

I did some investigation into options. I found this great YouTube video going over this same issue and several solutions.

I looked into these options and decided to go with the BTech GMRS-Pro and the push to talk (PTT) button. This works slick with my HJC/Sena helmet system, as well as the Cardo Packtalk (and likely most others). It pairs to the helmet intercom as a second phone. This way you can still use the intercom via Bluetooth and mesh as normal until you are too far away and the intercom drops. Then you simply use the PTT button to contact the other riders. If and when you get back in intercom range you can switch back. Switching back and forth is automatic really. The intercom is much preferred as it allows continuous 2-way communication and is lower power (less radiation). I prefer to use the radio only when needed (which happens on many rides). This BTech is really the only GMRS radio I found as of writing this post with Bluetooth profiles to support this configuration. I found others that support Bluetooth for app integration but this device also supports profiles for hands free communication and the PTT remote. This radio is also waterproof making it a good choice.

My first attempt at mounting the radio was on my rear bag.

I stuck the PTT button on the left grip at first.

This radio is a 5 Watt unit which is not something you want too close to electronics or your body really. I don't really need to see or touch the radio when riding since I have the PYY button and the mic and speakers use the helmet intercom system. I set the channel and volume and forget it. I decided to clip it into my rear pack, as far from me as I can. I zip the pack on the clip which retains it very well. The radio is waterproof so no worries there.

That all seemed like a great idea until we tried it while riding. The PTT button would only work sometimes, maybe half the time. I suspect the EMI from the motorcycles ignition system interfered with the Bluetooth signal from the PTT button. I decided it was time to mount the radio on the handlebars. I made a mount on the left side which is also only a few inches between the PTT button and the radio.

I found that having the PTT button on the grip was a problem since it would sometimes get in the way of the clutch level. I moved it to the mirror mount using a strip of Velcro tape and the strap it came with to keep it in position.

This worked OK but you have to reach for it and it can slide along the strap a bit. I finally moved it to the clutch lever.

Look closely and you can see one zip tie on each side of the clutch adjuster so it can't move at all. This is the best PTT switch position.

I used 2 small zip ties to retain it in place. Now I can use my index finger to press the button while riding without having to reach. It is also in a place where I would never hit it by accident and it does not move at all. This works perfectly!

The GMRS radio can also communicate with FRS and Ham radios. This means others can have an array of different radios and they can all work together. You just have to chose the same channel. FRS channels 1 - 7 appear to be the best choice for compatibility with both FRS and GMRS at 5W. Channels 8 - 14 are limited to 0.5W so not great for our purposes. Channels 15 - 22 would also be good as GMRS can go to 50W here but because of that high power capability you might pick of many other radios that are very far away.

Current (2017) FRS/GMRS Channel Table
FRS Channel	Frequency	FRS Max Power	GMRS Max Power
1	462.5625	2 W	5 W
2	462.5875	2 W	5 W
3	462.6125	2 W	5 W
4	462.6375	2 W	5 W
5	462.6625	2 W	5 W
6	462.6875	2 W	5 W
7	462.7125	2 W	5 W
8	467.5625	0.5 W	0.5 W
9	467.5875	0.5 W	0.5 W
10	467.6125	0.5 W	0.5 W
11	467.6375	0.5 W	0.5 W
12	467.6625	0.5 W	0.5 W
13	467.6875	0.5 W	0.5 W
14	467.7125	0.5 W	0.5 W
15	462.55	2 W	50 W
16	462.575	2 W	50 W
17	462.6	2 W	50 W
18	462.625	2 W	50 W
19	462.65	2 W	50 W
20	462.675	2 W	50 W
21	462.7	2 W	50 W
22	462.725	2 W	50 W

Here is how I setup my system.
Pair the BTech radio to your phone via Bluetooth. This is used to simplify configuration, not communication really. The Btech app uses this connection to communicate with the radio so the app can be used. Follow the instructions in the app.
Pair the BTech radio to the push to talk (PTT) button. Follow the directions that come with the radio and PTT button.
Pair the BTech radio to your helmet intercom via Bluetooth setting it as a second phone. Follow the instructions for putting the radio in paring mode. Then put the helmet intercom in pairing mode to pair to a phone. Treat the radio as a 2nd phone in this case. With HJC/Sena you enter the configuration menu using the helmet intercom buttons until you hear "pair second phone". Somewhat similar with the Cardo. On the Cardo hold the phone button until you hear "phone paring" then roll the roller forward and you should hear "second phone pairing".

I setup the BTech Pro radio to use both the internal speaker and Bluetooth at the same time. This way if I walk away from the bike I can hear the radio even with the helmet off.

I upgraded to the Cardo Packtalk Edge after initially writing this article. In general it works very similar to the Sena as far as radio integration.

The Cardo PackTalk has a weak microphone in my experience. I made this document to help make it better: https://docs.google.com/document/d/1pSw99DGPqQlbnlzCCxGzZUEQYRWzhN-yGs87ZEK4pRw/edit?usp=sharing by optimizing mic and speaker placement, as well as settings through the Cardo app. I also found the speakers are best placed so they actually touch your ears. I stuck them to the helmet lines on the outside. Sound is way louder this way.

If you are going to have just one of the systems, I would use the GMRS radio. This works for much longer distances which you will need off-road. When you space out to keep out of each others dust, and you begin to worry someone behind needs, help, you can always just call them and check in.

One downside of the radio is that others may use the channel you are on. Your group will all need to switch channels to find a clear one, which can be a moving target. Since it is analog communication you also get background noise and poor reception at times. Also you need to use a push-to-talk button of some sort. Using the one on the radio while riding won't work out. Most GMRS radios are compatible with wired remote PTT buttons. I use the BTECH GMRS-PRO since it can use a Bluetooth PTT button.

BTech now released another radio with integrated Bluetooth, the GMRS-50PRO