3 speed hub opinions
 

I built a CrossCheck commuter up with a Sram 7 speed hub. After being disillusioned by the mechanical friction loss (and subsequntly, poor climbing ability) of the 1st and 2nd gears, I changed the drive train over to a 42/16 single speed.

Well; I've been considering relacing that internal hub rear wheel with a 3 speed - in leu of the 7 speed. For one thing, it's nearly a pound lighter. However, I don't really want to buy one just to see if the performance would be any better.

So I am wondering if anyone has ever ridden Sram's 3 speed hub?

If so, does the low gear suffer from the same grinding mechanical friction that the low gears of the 5 and 7 speed internally geared hubs do?

If you haven't ridden the Sram; have you ridden other 3 speed hubs and, if so, what are your impressions? (and I'm talking about your personal experience - I've already read Sheldon)

Thanks in advance for any imput. DanO

I have experience with the Nexus 7 and Sturmey Archer AW-3 (3 speed) hubs.

I question why you even bothered building a Crosscheck which is an excellant frame with an internal hub? You really need an 8 or 9 speed with a tripple chainring. If the Sram Spectro 7 wasn't low enough, I highly doubt you'll get lower with the Sturmey Archer 3 speed unless you install a small chainring and remove the sprocket for a larger one with more teeth.

I was riding my 7 Speed Bianchi Milano last night and the friction loss is so real, the performance loss especially in the winter compared to my Univega street bike (7 speed) with 700 cc wheels. The hub weights a ton and it feels like I have 2 heavy water bottles attached to the wheels. It's not a bad hub if you ride less than 7 miles with no hills. It's almost bomb proof in the snow.

I actually like the Sturmey Archer AW-3 because (in some ways) unlike the 7 Speeds from Shimano, it actually has a "Direct Drive" that does not suffer the same performance loss. You're right about the weight of the Sturmy being lighter does make a difference and you can certainly feel it. You'll spend 95% of your time in 2nd gear (direct drive) but 3rd gear has horrible friction losses and 1st gear is just slightly better. Still. If you can set up a bike (With an AW-3) that has a low second gear, then 1st gear just might be enough for those hills. You'll compromise 3rd gear but then again you were not intending to go fast with this bike were you?

I still think you need to forget the 3 and 7 speed and just build a 8 speed (cassette) with 3 chainrings. In you're case, you'll never be satisfied with the friction loses of the AW-3. I don't mind but then again, I only commute 10 blocks to the train station with no hills. Consider youself lucky you didn't spend $800 dollars for a 12 speed Roaloff (sp) hub that weights MORE!

I question why you even bothered building a Crosscheck which is an excellant frame with an internal hub?

Well, I had done a bit of research and was aware of the designs inherent shortcomings, but was still curious/stubborn enough to actually see for myself.

You really need an 8 or 9 speed with a tripple chainring.

Actually, the bike rocks as a single speed. I'm getting used to humping it up the hills, but miss a higher gear for pedaling down the descents. So I am more interested in a spare rear wheel and easy to mount shifter with just a couple extra speeds, as opposed to a big range of gears. I think geared hubs are charming. But I'm also considering a second chain ring up front with a chain tensioner.

Thanks for the info. DanO

Or maybe a flip flop hub? You seem like a person who likes to experiment with different bike set ups (like me,) you might want to try that to get your lower gear.

I've rented bikes with all kinds of 3 speed hubs.... they were all dogs. Don't get me wrong, I like 3 speeds-- but if you have to climb any hill or go past 10 miles, well riding really sucks. Europeans love the damn things becuase they never break down-- I have an old Ward's 3 speed that's over 50 years old and I still ride it around the 'hood.

60 bucks will get you a cheap MTB derailuer and cassette-- with 42 teeth up frount and 11-32 in the back, problem solved. Becuase you're a strong rider, there isn't really much need for anything else.

I guess my legs are not sensitive to "friction losses". I have a Trek cruiser with a 4 speed hub and a compact crank. In level (six inches above the Gulf of Mexico, and sinking) Houston, the 4 speed works great. I have a Trek mountain bike with 24 speeds that is about eight pounds lighter than the cruiser,(which has big steel fenders, racks, etc.). But, when both bikes have the similar tires, they are equally easy to pedal around town.

The cruiser is my "rainy day" bike, as the sealed rear hub and coaster brakes work well in the rain. The compact crank allows "spinning" easily, compared with the larger cranks many companies use with their 3-speed and 4-speed models.

I have "toyed" with the idea of taking off the fenders, replacing the seatpost and handlebars with light alloy parts, and replacing the "heavy duty" tires with light slicks. The end result would be a maintainance free bike that weighed about 26 or 27 pounds - making longer trips a possibility...maybe even a 100 mile "day tours".

I modify my 3-speeds and one speeds so that they work better on moderate hills - that usually means gearing them down a bit by changing chainrings or sprockets. The idea of these bikes is generally that you are riding less than 10 miles - you have to realize and accept that they're not distance or speed machines.

I've got several bikes w/ 7-speed Shimano Nexus hubs. They do weigh more, but at night in the winter the most noticeable drag is my dyno...I find the 7-speed Nexus a bit 'crunchy' in first and third gear, but I don't necessarily think that translates directly into efficiency loss. These hubs are geared hubs, they don't have belts or clutches, so they don't really 'slip' at all, although maybe there's some friction loss you don't have with a derailleur setup.

My daily commuter bike has a 7speed Sachs (now SRAM) hub with coaster. I have never detected any grinding noises or any noticeable "drag". Perhaps I am not as sensitive as others to an alleged minute friction loss on a 42 pound bike with 622 X 47 tires. My alternate commuting bike (which I used for 5 years commuting in Germany and occasionally use here in the US) is equipped with a Sachs Torpedo 3 speed hub w/coater and is a fine bike for reasonably flat commuting. My family also rides on two other 7speed Sachs coaster hubs, and I have in the garage for occasional use a bike with a Schimano 7speed coaster as well as a relatively light weight bike equipped with a 5 speed Sachs Penta-Sport coaster hub. Again I cannot detect grinding or drag in any of them. My impression is that a single speed bike would not be a suitable replacement for any of them except as a beach cruiser or short trip flat land utility bike.

If you prefer fixed gear or derailleur equipment and rim brakes use them, and I am sure you if you are mentally prepared and tuned for detecting a gain in efficiency you will find it and be pleased with the improvement.

I though the 'crunchy' feeling was my imagination! It does translate direclty into efficiency loss and I also found out the Nexus 7 gets slower when the temperature drops below 30 F.

Everything gets slower/less efficient below 30 F. Especially the power source.

I've ridden a couple three speeds--mostly 30 or 40 year old Sturmey-Archer AW hubs. There's some drag, and they're not a lot of fun to ride in third gear unless you're going down a serious hill, but a broken in and well-maintained AW hub really is great to ride, and they don't present problems for me. Just make sure you have that second gear working.

On the other hand, i can't really say much about Shimano's new stuff.

I've cranked out quite a few AW miles and really enjoy the change in pace. I've got an SA AW built up onto a Sun CR18 rim and ridden up to 82 miles in a day on it and could have done more...got dark...a 3 speed isn't for every occasion but well worth trying...

meade

Does anybody know the gearing ratios in a Torpedo 3 Speed hub?

What is friction loss?

From the Sturmey Archer web site:

>>>>In simple terms, all gears rotate around a fixed pinion, the Sun Pinion. This is contained within a planet cage which also contains pinions, the Planet Pinions, which rotate around the Sun Pinion. If the planet cage is turned 90°, this moves the gear ring which rotates around the planet cage 90° plus an extra 5 teeth due to the rotation of the planet pinions. This 5 teeth is 30° making a total of 120°. This means the gear ring always rotates faster than the planet cage in a proportion of 120:90, giving a gear ratio of 4:3. Refer to the animation on the right.<<<<<

When the gears rotate around a fixed pinion, you can feel the peddals "crunching" as you try to move the cranks. Sturmey Archer claims they are about 95% efficient but this gets worse as the hub gets older. Even when the hub was new, 3rd gear was horribly high and rarely used. When the hub is dry, it's like having glue inside the hub.

I have a Sachs 3 speed on my road frame, works very well... no issues with climbing, I don't perceive any loss... and I switched to that from a single-speed. Got a Sachs 5 speed for my Raleigh Twenty... though that it far from being complete so I can't give a review on it.

I went a little nuts and picked up 5 nexus 7spd hubs on ebay a couple years ago. I've commutted on one for two years now. I've built up two for my kids (on older, non-suspension mtb frames) and was planning on two more for the other kids. Last summer I built up a touring version and went on a longer group trip. It worked out just fine even on a pace line with an aggressive group. I'm a little new to touring and also hadn't heard about inefficiencies with the hub. Now I feel like the bumble-bee that didn't realize it was too heavy to fly and did it anyway. It seemed OK to me. Coasting down hills was pretty equal to the fancy road bikes. Hmmm. Now I don't want to ride it anymore. Here's a link from my website describing it: http://home.att.net/~dbg/featurebike1.htm

Very interesting post. I am a commuter doing about 100 miles a week must consider this option more.

I have a SRAM Spectro S7 on order for my commuter bike, having given up on waiting for anything from Shimano. (And not having the money, guts to leave a Rohloff-equipped bike locked up on the streets of Manhattan) This is not to say, however, that I have lost all interest in 3-speed hubs.

My perception is that 3-speeds still offer a few advantages. In a shell of nearly the same volume as the 7-speeds they accomodate a much simpler mechanism. My guess is that more space for fewer moving parts allows the hub to be built more reliably. Secondly, with fewer gears, total friction/efficency loss is reduced.

From the moment I first saw the SRAM Dual Drive, I was never too enthralled with the concept. I know I'm not alone. Now, however, I think I may have a use for it. The Dual Drive is available in a version to which you can mount disc rotors. To my knowledge, this is not something that can be said of any other 3-speed hub. While the rear brake is certainly not as important as the front brake, I'll avoid using cantis or heavy drum brakes whenever I can. If I do try out this concept, I have no intention of employing the "dual drive" aspect of this hub, and only a single cog will be mounted to the cassette body.

Disc braking and the general reliability/relative efficiency of three-speeds make this hub a more compelling option. I suppose, however, that it would not be so difficult to adapt a disc rotor to other three-speeds. I've seen it done with the Shimano Nexus 7. (http://www.schlickjumper.de/parts/forum1_747.htm) Until someone manages to do this with a less expensive 3-speed, however, I'd feel inclined to spend the extra money and get something that works with discs out of the box.

Can anyone comment on the reliability, physical robustness, and relative efficiency (or lack thereof) of the Dual Drive?

I only own internal hub geared bicycles now. I can make 99% of the hills surrounding my locale with no problem-and no climbing out of the saddle at all. If I were to attend a business funtion I could use either of my bikes as the set-up is very clean and no telltale signs of grease marks on my good clothing.

I have a tandem with a sachs 3x7 dualdrive rear hub and double front ring (which means it is 3x7x2). anyway, the 3x7 hub is great and got us up some very steep climbs when we did loaded touring through france and we had very little trouble on flats and downhills. It's tough to evaluate how much friction loss there is in that bike, but I am so impressed with the hub, I just ordered another 3x9 sram dualdrive hub for my folding touring bike. It's a clean, reliable option and I never even considered whether there was more drag than a standard derailler setup. just my experience.

I've tested several internal hub set ups, including the SRAM 3-speed.

Bottom line: most internal hub set ups are going to be disappointingly sluggish. The 7-speed hubs run around 90 percent efficient in the best gears. (A clean derailleur set up or a single speed will run around 98 percent efficient.)

A possible exception, depending on your riding habits, is the SRAM 3-speed IN GEAR 2. Most 3-speeds are set up so that gear 2 is a direct drive. Because there is no relative motion of the gears in the hub, the hub runs as efficiently as a single speed (about 98 percent). In Gears 1 and 3 you are back to about 95 percent, however. (Some 5-speeds are also direct drive in Gear 3.)

I specified the drive train on the new Swift Folder (website) and ultimately ended up going with a SRAM derailleur. It's simple, inexpensive, light, and highly efficient.

On my own bikes, I run derailleurs except on the Swift I use for travel, which is a single speed with a 65 inch gear. I set up the travel bike that way for minimum weight and fuss. (I use the travel bike to get around the cities where I'm travelling, not for serious touring.)

Best,

Karl U.
Xootr LLC

Huh, I only drive internal gear hubs - SRAM 3 spd and a SRAM 5 spd. I don't think many people would note any major efficiency losses... I perceived little to on loss of efficiency going from SS to SRAM 3 spd in all 3 gears.

Yeah, I was wondering the same thing. If you are say commuting, how would you actually notice a reduced efficiency?

Let's take a 3 speed hub.

On average, I expect most of the distance will be done in 2nd, with the best efficiency for the hub. But wait, there's more. A single speed chain, being shorter and not running through the derailer jockey pulleys, will be more efficient compared to a derailer setup. So, for a certain part of the journey you are getting better efficiency than with a derailer. So perhaps, for the same pedalling effort, maybe a minute or so is cut off your journey time due to improved the efficiency.

Now, the uphills. Due to the fact that you can't shift to a perfectly comfortable gear, you may end up having to stand up off the saddle to make it uphill; this can result in a faster time because you don't want to get your speed so low that you almost fall over. So, it is reasonable to assume you are going to cut off a small amount of time there as well. Of course, you will be blowing a lot harder than with a derailer, but if you put the same gearing ratio to work there, I bet you wouldn't notice the difference if you had 10% more sweat?

For the downhills, sure you could not reach the same speed as with a derailer, the gears don't go high enough. So perhaps you end up coasting a certain part of the distance. So, some time could be added to your total. But because you are coasting, you are resting more compared to when you are getting the most speed out of your derailer setup, and being rested more gives you some more ability to tackle the next climb.

From this argument, you may not notice a difference at all. You arrive at your destination in close to the same time and you feel close to the same effort was expended.

As to the maintenance aspect, anyone who lovingly maintains their derailer, chain etc to run well would do the same for their 3 speed, so not valid to assume a "dry" hub and get your argument forward that way.

Instead of messing around with the rear, why not just find a triple with a good ratio of chainrings for the front?