I receive phone calls from city cyclists who build up single speeds, and then realize after a couple of weeks that their commute contains too many hills for a one-geared bike. Most of these riders like the clean design of fixed gear and single-speed bikes, and they don't want to hang derailleurs off of their bike frames. So, the next logical question they ask is what about building up a rear wheel with an internal hub.
Most people were introduced to internal hubs on bikes such as the proverbial Raleigh three speed. You flick a switch or turn a grip, and all the gear changing takes place inside the hub where you can't see it and the mechanism is protected from the elements. These hubs employee planetary or epicycle gearing.
If you are considering an internal hub, right this second, read the late great Sheldon Brown's instructions on Bike Frame / Hub Spacing before we go on. Sheldon has written a clear lesson on figuring out hub spacing, cold setting, and he has included helpful photos. Also, read his article on Chainline Spacing, so you get a general idea about what is going on between the alignment of the front and the back of a bicycle drive train.
Now, given the number of internal hubs on the market, which one is going to work with your brakes and bike frame? Internal hubs are made in models that are compatible with either disc brakes, or coaster brakes (you use your feet to brake, like when you were a kid), or roller brakes, or V brakes. Shimano, for example, offers two models of their 8-speed Nexus hub: Model SG-8C20 has an integrated coaster brake; Nexus Model SG-8R25 is both V-brake and roller brake compatible. Also check the spacing specifications for each internal hub in which you are interested on the manufacturers' sites. Most manufacturers make 3-speed, 5-speed, and 8- or 9-speed internal hubs. Rohloff does a 14-speed hub. My suggestion is to try to find a hub that suits your current brake style, gearing comfort needs, and minimizes the amount of deforming you need to do to your frame in order to make the hub fit. If you are trekking across a continent, make sure to pick the hub that works with your adventure terrain. Strong suggestion: If you are thinking about an internal coaster hub for you city bike, and you ride like a wild cat, make sure to run a front brake also. You only need to skid through an intersection once to realize that coaster brakes are not made to stop late-for-work coffee-drinking adults riding at full tilt. (Been there, done that.)
Definitely check out this comparison of internal hubs by Marco at Hubstripping.com. You technical cats who love look at mechanisms and reading specs, click around on Marco's site until you get busted by your boss or co-worker for obsessing over gearing ranges and ratios while on the clock. Check out the manufacturer sites of the internal hubs Marco compares: Shimano, SRAM, Sturmey Archer, Rohloff, and Fichtel & Sachs. Wheelgirl bike shop recently built up some Nu Vinci hubs, which are heavy if you are riding a ton of hills, but useful for general, low-maintenance cycling. Marco has info on these hubs also. If we can build you wheel around your favorite internal hub, email us. We do build wheels for those living outside the Bay Area. The shipping is less than $20.00 to send a wheel set UPS ground.
(Photos of internal hubs, left to right, Rohloff, Shimano, SRAM, Sturmey Archer, NuVinci. All photos lifted from respective manufacturers' sites.)
