Today I got a few of the parts needed to start Sara’s build:


From left to right we have her new front hub, rear hub, and headset.

The front hub is the part I was most excited to get.  It is a PD-8 Dynamo hub from Shutter Precision.

Isn’t it Pretty?

I have been wanting a dynamo hub for quite a while.  I love the idea of not having to worry about batteries for lights, and having the potential to charge things like my GPS, phone, MP3 player etc. while on the road.

For some people, the worries about lighting may seem a bit silly; afterall, the general idea is to be done riding before it gets dark. Most of the time this is true, but, the few times that I have been caught out after dark the rides were extremely nerve-racking.

One ride that comes to mind often was a time I got way behind schedule due to routing problems and a six-mile stretch of gravel.  On that occasion I rode in the dark for almost two hours on gravel and a state highway with no shoulder with a rather dim headlight, and my headlamp.  With the combo of the two I still had a hard time seeing very far ahead which was especially troublesome on the gravel.

Then there’s the fact that I seem to spend a lot of time riding in rain and fog (I have bad luck with weather) which are also times when reliable lighting become major safety issues.  And, last July when I was riding through Kentucky I found myself really wanting a reliable and bright light so I could start my rides before the Sun came up to avoid riding during the hottest part of the day. The lights that I plan on pairing with this hub are quite powerful, and, thanks to the hub, will always have power, so the Sun’s being out will no longer be a determining factor for when I ride.

The ability to charge things comes up more often than wanting light. On past trips I have used a combination of a solar panel, battery charger, and electricity at camp sites, in restaurants, behind soda machines, and anywhere else I could find an outlet to keep everything charged.  For the most part, this system worked okay, but it sometimes became quite a chore to find power.  There were a couple of times on my trip through Kentucky last year where the stars aligned against me, and it became something of a struggle to keep my phone and GPS charged; and more than once my choice of campsite was determined by  the availability of electricity.  With the new hub, these issues become nothing but unpleasant memories.

Two things have kept me from switching to a dynamo hub before: weight, and rolling resistance.  On the weight side, the SP hub comes out 108 grams (3.8 ounces) more than the Shimano XT hub that I have been using (XT M756).  Once I did the math with the weight of the hub and the lights I want minus the weight of my current hub, plus the solar charger and my current lights and batteries, I ended up saving just over a pound.

But…there is a very real difference in the rolling resistance in a dynamo hub vs a regular hub, which means more energy output to move.   I chose this specific hub because it offers the lowest resistance of the major brands, and has received a lot of praise.  Still; after going through a rather dizzying array of formulas on various websites regarding wattage (output) vs weight, all I can say is that there will be a little extra energy needed to move my bike with the new hub compared to a regular hub.  But, after acquiring lighter camping gear, and lighter components I will have significantly lowered the weight I will be carrying when compared to previous trips.  Add this to gaining a bit more of a granny gear with the 10 speed drive-train that Sara is getting (more on that in a future post), and I believe that I am coming out ahead on the power-needed end of the spectrum, while definitely gaining on the electricity-production end.  I don’t have all the math to prove this, but as long as I believe it then it is fact to me.

Both of my new hubs will eventually be laced to DT Swiss TK R40 rims*.  This will be done by a wheel-builder, not by me.  While I understand the concept of wheel building, I have neither the equipment or expertise to pull it off, so somebody who knows what he/she is doing will be contracted for this.

Installation of the headset will also be done by someone else since I don’t have the tools for that either.  I could buy the tools and do it myself, but the cost of said tools vs the cost of having it done just don’t work in my favor especially when you consider that such a thing doesn’t have to be done very often and if done incorrectly can cause some serious problems.

So, it seems that it’s time to find people to install/prepare my shiny new components.

Updates will certainly follow.

*Edit-  I eventually decided to bite the bullet and went for the slightly more expensive Mavic A719 rims.