If you want some peace of mind, get a SPOT emergency beacon or PLB. In my opinion, these are key if you do any riding or other wilderness activities in areas that don't have cell reception. The North Shore counts - lots of areas with limited or no reception. Definitely a must-have if you're going solo. Of course, if you're riding solo, crash, and knock yourself out, a beacon won't be much help.
If you look through any SAR accident log, such as AAC's 'Accidents in North American Mountaineering' annual volume, pretty much every major incident is significantly complicated by a missing communication link.
In terms of SPOT vs. PLB: a SPOT is cheaper in the short term but definitely is a far inferior device. PLBs operate on a dedicated 406 MHz SAR band and pump out way more power compared to a SPOT (ACRs PLB signal is 5 Watts, 12.5 times the power of a SPOT unit). SPOT is a private company and your distress signal goes first to a private emergency centre and is then relayed to the appropriate local authorities. PLBs go directly to SAR and is recognized immediately as a true emergency. PLBs have a very stringent quality standard with built-in redundancy in the form of the older 121.5 MHz homing frequency.
One other thing to be aware of is that SPOT requires an annual subscription fee of $99 or $149.99 if you want tracking. The device cannot be used until the subscription fee is paid. The 5 year ownership of a SPOT unit is much more expensive than a PLB or EPIRB: $149 unit cost, $499 in subscription fees, $250 for tracking fees, plus GEOs insurance (total 5 year cost can range between a minimum of $648 to as high as $1,649). If the Globalstar company were to close, your SPOT tracker would not work anymore. EPIRBs/PLBs do not require a subscription fee since they use the Cospas-Sarsat satellites (a humanitarian SAR system fully funded by member states of the U.N.). If you are looking for a tracking device that does not have to work every time, get a SPOT. If you want a life saving device, designed and manufactured to work when your life depends on it, get a EPIRB or PLB.
Oh and it goes without saying that you should always leave a trip plan when you go riding. Numerous cases of people going for a hike and getting lost and perishing because no one had any clue where they went. One recent incident was that guy who went for a hike in Hanes valley 3 years ago, broke his leg, and spent 10 days out there - somehow survived. Accidentally found by a off duty NSR person going for a trail run through there. Stupid.