Winter is coming to SoCal. Well, actually that doesn’t mean much – a handful of rain days at worst, temperatures in the high 60s instead of low 80s during the day, and more UGG boots and less flip-flops on the beaches. However, the winter days are shorter. We now commute to work and back in the dark, start to roll to our weekend group rides in the dark, stay out on the trail for too long, and our post-work intervals become a night shift. Since we want you to see and to be seen in the dark and not getting caught out by it we created the ingenious GRVL38EL. The GRVL38EL is the electrified sibling of the aero-gravel GRVL38 using the same super-light and ultra-wide aero carbon rims and is built around a Shutter Precision dynamo hub.
The Dynamo Hub.
The Shutter Precision dynamo hub is the perfect companion and mobile power plant for your daily commute, bikepacking adventure and ultra-endurance race. It has a 6 Volts/3 Watts power output and reaches 78 % efficiency at only 9 MPH (15 km/h). This is the globally accepted German StVZO (Strassenverkehrszulassungsordnung) standard how to design and test bicycle dynamos. This means at low speed the dynamo will power your lights and charge your mobile phone, GPS device, and other essential electronic gadgets on the go. Any go!
The dynamo’s durability and reliability has been demonstrated in races like the Tour Divide. It is one of the most difficult ultra endurance races on the planet starting in Banff, Canada and finishing in Antelope Wells, New Mexico. During 2700 miles the Tour Divide climbs 200000 feet through a mix of forest roads, single trail and a tiny weeny bit of tarmac. Under these gnarly conditions great racers of the Tour Divide have used Shutter Precision dynamo hubs on their bikes. Among them are the great Mike Hall (1st, 2013; RIP), Jesse Carlsson (2nd, 2013) and Jefe Branham (1st, 2014). What is good enough for these superhumans is surely good enough for us mortals.
The use by professional athletes should also alleviate your concerns that a dynamo hub may slow you down too much. The drag is actually pretty low. At approx. 20 MPH (32 km/h) with no device connected the drag is only about 1.75 watts and under full electric load it only goes up to about 7 watts*. Not too shabby considering your may carry a few bags and use bigger tires when riding the GRVL38EL.
*https://www.cyclingabout.com/how-much-do-hub-dynamos-really-slow-you-down
The Lights.
Most of us use lights with rechargeable batteries and they work fine for a 30 minute commute or hitting the trail after dark for an hour or two. But many commutes and journeys on the bike exceed these hours. Choosing a dynamo to power your lights means you have endless eco-power and will never run out of charge whilst in the middle of traffic or worse forest. We experienced it is really nice to have blinking lights all day when you ride for hours on the shoulder of a misty Washington highway in November while being passed by dozens of log-hauling trucks. Luckily Washington drivers have been most courteous on this trip.
While you can wire any light to your dynamo hub to brighten your way, you would miss out on the full potential a dynamo hub has to offer. A much more elegant solution is Sinewave’s Beacon we offer with the GRVL38EL and in our shop. The Beacon is a bright, beautiful, waterproof dynamo-powered headlight that can connect a rear light AND houses an integrated USB charger to power your phone, GPS and more. Nothing is left to be desired with this eierlegende Wollmilchsau (literally “egg-laying wool-milk-sow”).
The USB Chargers.
If you don’t plan on riding in the dark or are genetically blessed with night vision and autoluminescent hair, but still want to charge your devices on a remote bikepacking adventure you will need an interface between the dynamo hub and your electronic devices. Perfect solutions are Sinewave’s USB chargers, the Revolution and the Reactor we both offer with the GRVL38EL and in our shop. Both do the same job and start charging at 3.5 MPH (5.5 km/h) reaching full charging at only 9 MPH (15 km/h). They are waterproof and have gold-plated USB connectors to withstand the elements. The externally wired Revolution comes in a tiny package and can be mounted to your stem or frame, or just stored in one of your bags. The Reactor replaces your headset cap and is internally wired through your fork. If your fork allows internal wiring this is the neater and more permanent solution.
The Alternatives.
And to convince the last skeptics let’s have a brief look at power source alternatives you could take on a bikepacking trip off the beaten path. A solar panel can easily be added to your bikepacking setup and doesn’t require you to be in motion to charge your devices. But let’s be honest you want to be in motion, that’s why you are reading this, and ride until it is dark with is no daylight left to use a solar panel. And that is the solar panel’s Achilles heel, nomen est omen it heavily depends on the sun or at least good weather. If you travel North in fall a solar panel won’t be of much help.
Rechargeable battery packs with a decent capacity of 20000+ mAh are heavy. For instance an Anker PowerCore II 20000 weighs 360 grams on our Feedback Sports Alpine scale. This is about 50 grams more than the added weight for the dynamo front hub (approx. 274 grams) of the GRVL38EL and the Sinewave Revolution USB charger (37 grams) combined. And the limited power supply can be a problem if you are away from civilization for a few days. Charging a battery pack takes a long time, much longer than a morning coffee stop on your bikepacking trip in the nearby village.
GRVL38EL specs:
- Rims
– disc brake specific
– 38 mm deep and ultra-wide 32 mm external & 25 mm internal aero rim profile
– tubeless-ready for excellent rolling resistance, weight and puncture protection - Decals
– Stealth Black Reflective vinyl that headlights can’t miss adding an extra layer safety - Dynamo Front Hub
– ShutterPrecision Centerlock
– at low 9 MPH (15 km/h) it delivers a 78% power output of 6 Volts/3 Watts
– when the hub is not connected to a device the drag is only 1.75 watts at 20 MPH (32 km/h) - Rear Hub
– Hope RS4 Centerlock
– HG11, XD, XDR or Campy freehubs - Spokes
– Sapim CX-Ray aero spokes
– 28 spokes front and rear - Nipples
– Sapim PolyAx aluminium - Axles
– front: 12 mm, 15 mm or QR
– rear: 12×142, 12×135 or QR - Included
– dynamo connector plug, tubeless tape and valves - Weight
– from 1770 grams
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