Shimano Dynamo DH-3N72 Generator Hub

This is a very good hub that is unpopular (and priced low) for a couple of reasons - it is for a 36 hole rim whereas 32 hole rims are current, it is for rim brakes whereas disk brakes are more in mode, and - battery powered lights cost less, produce no drag and give more light. The catch to batteries is that they do not power things without running down - kind of like leaky inner tubes that you need to be always pumping up assuming they never run out when you really need them. All things being equal, a symmetric wheel is stronger than a dished wheel and 36 spokes is stronger than 32, so fashion makes for a weaker wheel.Obviously a 36 hole rim would have to be laced and trued to this hub. The key to that is the measurements needed to correctly estimate spoke length. The only given is drop-out spacing: 100 mm. Shimano used to provide flange offset from center, and the diameter of the hub's spoke hole circle – Pitch Circle Diameter. If the reason they no longer provide these measurements is because of variations, it would be sensible to make the measurements yourself, even if you didn't have to. Measuring the hub is the easy part. Getting a good Effective Rim Diameter is the most important dimension - that is from where the spokes end in the rim on one side to where they end in the rim on the other side. Use a tape to get the inside diameter - eyelet to eyelet. Then poke a nipple through and mark it at the eyelet. Measure the concealed part of the nipple to where you want the spoke to end - in there pretty far but not flush with the end - and add that length to both sides of the inner diameter to get ERD. The only other factor is the number of times the spokes cross each other, which is your choice to make.

My only gripe was that Amazon somehow tricked me into payingfor expedited shipping. The product is excellent, it'd get five starsbut for the extra shipping charge.

About 10 years ago I got a stock bike with a generator hub (Novara Fusion) to try something new. Previously I powered lights with a bottle generator (runs by friction off the wheel) or batteries. As a regular bike commuter, I'll never go back to batteries or bottle generators. I bought two of these hubs and retrofitted my wife's bike, and also my daughter's bike so I wouldn't have to worry when she was riding to school early in the winter, or in the evening. I haven't had any problems with those. If you don't know how to build wheels, you can buy pre-built wheels with these generator hubs for a modest price.This particular hub isn't the top of the line, but I don't need that for commuting and general riding. This hub is ultra-reliable and produces enough output to power a tail light and a bright headlight. Unlike a bottle generator, you won't feel the drag, although this is about a pound heavier than an ordinary hub.Be sure to pair this with lights designed to be hooked up to generators. Also, get lights with a stand-light feature, which store energy and stay on for a few minutes while you are waiting at a stoplight. These lights are not cheap but the system as a whole (generator + lights) is economical and reliable if you want to use a bike for transportation regardless of the weather or time of day.A previous reviewer, R. Powers, says "Cannot figure out why everybody doesn't have one." I think the reason is cost. You have to lay out about $200 for a good system up front. That sounds ridiculous compared to a $15 blinkie and a $25 battery-driven headlight. But that isn't a fair comparison. To get a battery system with this much power, you would have to use rechargeables. So you would be fussing with a charger and batteries every day. For $200 you get a generator-driven lighting system that is safe and reliable as a car lighting system, that will last for as long as you own your bike, with no maintenance. I have never had to fix one of these systems except to re-fasten a wire.

Laced this hub into a 26" mountain bike rim, and used the old mountain bike for a metric century ride in February this year. Worked really nice. I love having a quality lighting system on my so I don't have to worry about waiting to depart on a ride before sunrise, or be afraid of finishing a ride after dark.

I gave this a 4 star because I like the concept but they won't fit my bike. My bike sits on a 1 sided axle with bearings on either side of the hub. This hub requires to mounts, such as forks. I am sad because my bike won't accept these and I intended to use this, along with a dc/dc stepup board to get 12v's for continuous led strip lights. Essentially I was looking for a way to light my bike up like a Christmas tree so vehicles can see me at such a low stance as my trike has. I hope shimano can come up with a bearing style hub with the same power settings.

I got my hub and quickly laced up a rim(first one ever and it took about 15 minutes + tensioning/truing).At first I thought it had a bit of resistance till i got the rim on and then decided it was super smooth. the resistance it gives is so low I will likely hardly notice it when riding long distance. I put this into a trailer wheel rather than a front rim since my intended use will be for long distance/multi day rides.As for the operation of the hub, I tested it with my meter and it consistently puts out between 0.6 and 0.8 amps. The voltage in the funny thing, I can get 6 volts at 5mph in a 26inch rim. When I am at cruising speed, 15-20 I am getting 14-16 volts. I always planned to have a voltage regulator in use but now I see how vital it is.Lastly about the power... I really wasn't thinking much about it at the time but this is an AC generating hub(as I assume most if not all are). Because of this I need to get a Bridge Rectifier(Diode Bride) it convert from AC to DC as well as a capacitor to smooth out the power source so my gadgets get nice clean energy.It works as described and possibly even better. I am rather excited to get my charging station wired together so I can keep my gadgets powered up on the road.