Review and Giveaway: Bike2Power for the iPhone and Smartphone

The wire from the dynamo to the USB charging unit is long enough so that you can mount the dynamo in the rear on the seat stays or even chain stays, which are much smaller tubes.  I did not attempt this on this bike, but would mount it there on my other road bike (in part because it has an even larger fork).

The dynamo itself: I recommend using the cap for the dynamo, particularly with road bike tires (you know, the skinny ones!).  It is a hard rubber compound that easily fits on top of the dynamo.  This is a new feature that is being added to kits and will be available on “RAGBRAI edition” kits.  There is not a noticeable difference in the rate of charging, and it does reduce the white noise generated by the dynamo when engaged.

Be aware that without the cap, the teeth of the dynamo will adversely impact the life of the tire, especially the thin-walled road bike tires.  It may not be as much of an issue with thicker tires.

Also, be careful when mounting the dynamo, especially if you choose not to use the cap.  It is very important to make sure that the dynamo head is flat against the tire when it is engaged.  I tried different mount locations and for one had the dynamo mounted at an angle where the head was not flat against the tire.  As a result, the teeth of the dynamo head chewed up the sidewall of the tire.  You can see the result from the pictures linked to the end of this review.

Preparing to Use: If your phone is in a case, you will need to remove it in order to fit the phone in the cradle.  You then plug the USB cable into the phone and the charger unit.  Be sure to have some twist ties to tie up the extra length of wire from the phone.  (If you have an extra cable, you could tape it up and keep it in your saddle bag.)

The dynamo has a release tab to disengage the dynamo from the tire when the charger is not in use. This is a great feature as there is some white noise when the dynamo is in contact with the tire, as well as resistance.  And, as every cyclist knows, resistance means you have to put in greater effort.

Please note that the release tab for the dynamo is located on the inside of unit – between the dynamo and the wheel.  You should only press it when you are at a stand still and never when you’re moving.  Perhaps this can be changed in the future.

Another issue to monitor is the contact between the dynamo and the tire.  Be sure that the top of the dynamo is spinning constantly when in motion.  If it spins only intermittently or not at all, you will have contact and will not be charging your phone.  If, over time with uses, the dynamo doesn’t come into full contact with the wheel, you will need to readjust the mounting bracket angle.

Use:  On a 40 minute ride with the Cyclemeter app open and running, the Spin POWER increased the charge on my phone +16% (from 51% to 67%).  At that rate, you can expect to go from dead to fully charged in about four hours.

You should note that the Spin POWER is not water proof.  If you are riding in the rain, you will a) not want to connect the phone and b) wait until the charger is completely dry to use it.

Photos: On Flikr, here:

Retail Price: $79.95


While there are tweaks that can be made to improve this product further, I feel that the Spin POWER 4 is a great product for keeping your phone powered on the road. I will be taking one with me on RAGBRAI this summer so I can stay connected all week long.


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