Originally Posted by chainlessguy

Seems there are a lot of posts in here from contributors that have no direct experience with or knowledge of shaft drive bikes. I do, so I am happy to get involved and bring some first-hand knowledge to this thread. Full disclosure - I have been involved in the manufacturing and sales of shaft drive bicycles for nearly ten years. But this said, safe to say I know a bit more about them than anyone else on this post. I have ridden bikes all my life. Every kind. And its true that shaft drive bikes are not for everyone. Different strokes. But shaft drive bikes are excellent for what they are designed for - clean, safe, incredibly low maintenance, easy to operate, and solid performance. Shaft drives for commuting in foul weather dramatically reduce maintenance time and costs. Shaft drives on folding bikes are clean and safe to handle and store. Shaft drive recreational bikes are easy to operate, very smooth to pedal, and easy to maintain. Shaft drive bikes are also outstanding for public bike share systems.

But this is not what most of this thread has been about - it has been about the performance of shaft drive bikes. I can tell you that today's shaft drive bikes offer every bit of the performance of a chain-drive internal hub bike, but without any external moving parts. For instance, the new Sussex 4th generation shaft drive - which is lighter, more efficient and more durable than previous shaft drives - is only about 12oz heavier than a chain. The efficiency loss of the spiral bevel gears in the shaft drive is 2% for each 90-degree turn. There are 2 in the shaft drive - one the front gearbox, one at the rear. Then there is some loss of efficiency from bearings and lubrication. This puts the shaft drive at about 90-92% efficient. All the time. No tune-ups or adjustments. The new 4th generation shaft drive from Sussex also is lubricated once when the bike is new, and then again at about 5,000 miles. No tools required. And as for the efficiency of a chain-derailleur bike, the reality is that these system vary tremendously in efficiency. Variables that effect riding efficiency on chain-derailleur bikes includes: condition and lubrication of chain, condition of teeth on sprockets, slack in chain, pitch angle from front sprocket set to rear, friction of front-rear derailleurs, efficiency of shifting, weight and material construction of gear components, speed of shifting, drop angle of tensioner, external weather conditions, and more. I hear people say that chain bikes are 97% efficient. Yeah, I read the same study. What this study also said was that this 97% efficiency was for a single-speed bike with a chain perfectly tensioned, aligned and lubricated. This does not represent 98% of the chain bikes on the market. Most chain-derailleur bikes are not even close to this rate of efficiency. In fact, even well maintained chain-derailleur bikes have very different efficiency from gear-to-gear. Some gears may be as high as 95% efficient in best case; some may be as low as 75% in worst case. Read the literature if you really want to know.

With all this said, after years of comparing the two, IMHO, its splitting hairs. People are not buying commuter bikes, folding bikes and hybrids in general because they are the most efficient bike in the world. They are buying these bikes for their function or enjoyment. So within the markets that shaft drive bikes are offered, they are just as efficient as their chain bike counterparts; but without all the key moving parts all exposed, which has its appeal both functionally and aesthetically. The weight comparison is nearly the same. The 12oz difference can easily be made up in other components on the bike. And despite what you might have read, a chain guard does not do the same thing as a a shaft drive. It certainly is not going to stop your bike from needing the same maintenance as without it.

I hope this information helps.