30 March 2011

Meine neue Brücke

Hier ist die neue Brücke, von der ich neulich berichtet habe. Die Parks auf beiden Seiten sind auch schon im Bau, so dass man bald von meiner Haustür bis nach Tempelhof durchs Grüne fahren kann.
neue Fußgängerbrücke von der Schöneberger Insel nach Tempelhof

27 March 2011

Jack the hub stripper

Yesterday I stripped my first hub (a Sturmey Archer 3-gear with back-pedal brake) and put the photos of the parts I found inside in a flickr set.

Let me just show you the most interesting pictures here:  

On top of the first picture are all the parts I took out from the brake side of the gear (including the main shaft which comes out on this side) and on the bottom is just the drive side bearing cone with its nuts. I named all the parts using part names I found in technical descriptions of similar gear systems. I think my names make sense, but other description you might find might use different names for the parts.

both sides opened and main shaft taken out on brake side

Note especially the main shaft on the top left, with the planet carrier and its four planet wheels (two shown) and the sun wheel, which is hidden, but can be felt when turn the planet carrier on the main shaft, because the sun makes the planets turn. Planets, sun, and ring gear are permanently engaged with each other, no matter what drive speed is chosen.
As for the changing of speeds, you can see a little piece sitting in a slot of the main shaft. This piece is pulled by the actuating cable (thus, the speed-change lever) and pushed back by the spring shown at the bottom. The little piece then moves a larger piece which on the photo is shifted leftwards on the shaft. I call it the “clutch element” and it normally sits right on top of the little piece.

The second picture shows the remaining parts, which are the most interesting, because those parts take part in switching the gears.

ring element, drive side cover, and driver taken out

The part on the left with the two big pawls is the “ring element” on its inside is the ring gear (interior toothing) of the planetary set. The pawls on the outside engage with the hub shell to drive it, but in some gears the metal ring shown above the ring element will cover the pawls, so that the wheel can be driven by another part at a different speed.
The part in the middle screws into the hub shell and has teeth with which pawls can engage (I don't yet know which pawls tho). The part on the right is the “driver” because it carries the chain sprocket and brings the drive input into the hub. It has two pairs of smaller pawls (hard to see because of the grease, here's a close-up). Depending on gear, the driver will drive the ring element, the planet carrier, or the hub shell directly. I haven't figured out the details of this yet, but I think that the “clutch element” shown in the first picture is playing an important part in it. What's making things more complicated is that the driver also needs to actuate the back-pedal brake which I think is why the pawls on the driver are bi-directional.

On the output side, the hub shell will be driven by the planet carrier, the ring element, or the driver directly. I have heard that the brake element (first picture, top middle) is part of the transmission path in some gears, which I think explains why it also has a pair of free-wheel pawls on it.

I'll post more details about all this when I have figured it out better. 

22 March 2011

a disappointment, a niche well-filled, and a dare

Prima Parte – Una Delusione

If you look at the specs SRAM's i-motion 9 gear hub, they are really impressive. Unlike Shimano's proven excellent Inter-8 hub, the gears are spaced very evenly. Unlike previous SRAM hubs, the actuation doesn't sit vulnerably outside the bicycle's frame, but is inside like the Shimano's, but still much easier to take off when changing a tire. The hub got excellent reviews in magazines and blogs (like this one on hubstripping), many bicycle makers embraced it, and the first bunch of buyers were happy. It looked like the German SRAM engineers of Schweinfurt had been able to offer a real alternative to Japanese bicycle parts domination.
However, if you look at the same product right now, there's some disappointment around. The hub really delivers on good gears and easy shifting, but reliability doesn't seem to be so good. Thinks break, hubs have to go to maintenance. Maybe the quality isn't even worse than previous SRAM hubs, like the Spectro S7, but the good performance of Shimano's products which are used in applications more demanding than what gear hubs previously experienced. Looking at the market right now, there are less manufacturers using this hub in their bikes. Biking through Berlin I see hundreds of bikes running Shimano gear hubs (especially the Inter-8 premium and Alfine 8), but I rarely see an i-motion 9 around.

I had decided to get an i-motion 9 for Knicki, because I have the inter-8 on Speedy and like to try something different. But everywhere I look for answers to some buying and fitting details, I find people telling me that I shouldn't get it and get Shimano instead. Of course, I don't know if the hub is really that bad. I requires much experience to make such a statement and I don't know who I can trust. Maybe, it's just bad marketing and bad crisis management at SRAM, while the product is not that bad. But frankly, for my bike I want something desirable and the i-motion isn't desireble to me any more.

Seconda Parte – Una Nicchia ben Riempita

sdfasdf While researching gear options for Knicki I also found Sturmey Archer's new X-RF8 hub. I could write a half-novel now about SA's history and how Sunrace of Taiwan saved this company with very long tradition (or at least some of their heritage). And I could as well talk about the strong parallels in SA's and F&S' history. Fichtel & Sachs (gear hub makers now part of SRAM) and Sturmey Archer both started producing three-speed hubs at the beginning of the 20th century and I am still not quite sure who of the two did actually invent the thing. But to cut a long story short, I want to talk directly about the very interesting business strategy of Sunrace in dealing with SA. The smart thing they did is not to face their competitors directly with similar products but fill market needs that are unsatisfied by the competition. Of course, a large part of their business is selling slightly improved versions of their traditional three-speed hubs to bicycle makers who have bought them for a long time and are still fitting them on (some of) their current models. But another part is the market for fun-bikes and fixes which they provided with a fixed-wheel gear-hub (that is, there is not free-wheel in any gear) and with a gear-hub that shifts by back-pedaling, thus without any cable or switch disturbing the clean looks of one of those “pure” single-speed bikes.
Another big market for SA is folding bikes. Many of their gear hubs are narrower than those of the competition. For example, the five-gear hub fits the Brompton frame without modification. (Even the 8-gear fits the Brompton, albeit with some widening of the frame.) SA also makes a hub which specifically combines with the Brompton's two-sprocket derailler to create a system of six evenly spaced gears. The principle is similar to SRAM Dual Drive and Shimano Intego, but the market is specialized and the product is the only one that not just dispenses with overlapping gears (dual drive 27-gear is just 13 or 15 “net” gears), but it also results in evenly spaced gears. It's been a close cooperation with Brompton Bicycles and it's called “Brompton Wide Gear” (BWR).
But it's SA's 8 gear hub, with the poetic name “X-RF8” (rear freewheel, as opposed to the RD8 with integrated drum brake) that I find particularly fascinating. It is not just constructed narrowly to fit smaller bikes. It also has the gear arrangement designed for smaller wheels. I find that particularly interesting, because I had previously wished that such a hub would exist. A bike with small wheels always needs a larger chain wheel or smaller sprockets to get the same development (distance traveled per crank-turn). The Shimano Inter-8 which I have in Speedy has its neutral gear (that is the gear in which the gear hub behaves like a non-gear hub) in position 5. I thought that if it was in position 4 instead, then the entire gear range would have a larger development and thus work with a larger sprocket than the current, tiny, and rare 14 teeth I am using now. And it is just this idea which engineers at Sunrace have take to their hearts and used to design into the hub. The result is a system where the smallest gear (first gear) is the neutral one and the other seven gears all are longer than neutral. This means that even with small wheels, a bicycle can use standard sizes for chain wheels and sprockets and yield a good development. Smaller chain wheels mean prettier bikes and more possibilities to mount chain guards. Larger sprockets mean less wear and tear. Sturmey Archer being the only company that's building such a hub means they'll have a lot of happy customers. That is, in theory at least. I find it disappointing that I don't know any folding bike manufacturer who's actually offering series models with the X-RF8. A quick googling only shows some custom-tuned Bromptons. Well, Sturmey, I wish you more success in the future with this great idea.

Terza Parte – Una Scommessa

Now that I am doubting to buy the i-motion 9 hub (and not wanting to buy something exotic as the X-RF8), I am almost back to square one again. For sure, I could just get another Shimano Inter-8, which would also be a different one than Speedy's because the product has since been upgraded with the “silent” roller clutches. But I really want to try something different and I especially want to try a hub with more evenly spaced gears so I can feel the difference to the Inter-8's very oddly spaced gears (14 to 22% for the different shifts).
So now, 2011, it's also the first season that Shimano's Alfine 11 is on the market. A device that on paper looks just as good as the i-motion 9 and better. And it comes from the market leader in sporty gear hubs. But does that mean it's gonna be really good? For one thing, it has its neutral gear in position 5 of 11 which means that it is also much easier to fit onto a twenty-incher (such as Knicki), which solves a problem that I had with the i-motion 9. On the other hand, I'd really like to build a wheel that's gonna last and create a bike that also has a good resale value when our relationship ends one day. I'd really like to wait just one more year to see how the new hub does in practice. But Knicki desperatly needs a revamp!
How will things work out for us? Read it on this blog. Sooner or later.

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6 March 2011

Another Spring, another Speedy-Tuneup

This year I did it earlier than usual, because my yellow darling had a flat rear tire and taking the rear wheel out is so much work that I used the occasion to also replace the chain and clean the gear actuation on the hub with much affection.

I had learned from past experience that taking the chainglider off and back on will bring dirt on the chain, so I did everything with much care this time. I spent a lot of time on everything, but I think that's perfectly ok to do once per year. For this year, I want to protect Speedy better from rain. I didn't get a basement to rent in my building, but I have a nice bicycle cover for outside or could take him up in my room with the other two bicycles.

I had felt that the chain had suffered a lot in this year's rain. Standing outside day and night is much worse than occasionally riding through rain and having a dry place to sleep. I thought that the sprocket might also need to be replaced, since last time changing the chain, the new one wouldn't fit on the old sprocket. But in fact, I measured the chain and it was just worn out, not totally over worn-out and the sprocket looked just a little worn. In any case I was thinking of getting a larger sprocket to vary my gears a little bit, but because of the flat-emergency I didn't have time to purchase one. (Special-size sprockets are rare!) I guess I'll do the sprocket-varying next year.

I am quite satisfied how the clean-up went. I am only doing it once a year or even less often, and last year at Thomas' shop in Schaffhausen, I didn't pay attention to everything he was doing, but I still remembered the steps well (or at least figured them out). For the rear wheel, the brake cable and torque arm need to come off, then the chainglider (at least the rear part), then the shifting cable, then the wheel comes out, then I can take apart the gear actuation to clean it. When putting things back together I thought of using the tuning-marking to adjust the shifting cable really well. I also thought of giving some slack in the cable housing so it doesn't un-adjust when the rear wheel is moved a bit to tension the chain (as had happened just two weeks ago). I just thought about it after doing the adjusting, so I had to do it again.

Reminder for myself: when I cleaned the gear actuation I found that the dust cover of the hub had a little crack. I need to get a new one, so I can put it on next time I change the chain. Shimano part Y-34R 98110. I also need to find out which tool is needed to take off the sprocket since I never did this myself.

my new bicycle commute to work

Größere Kartenansicht

It's a wonderful 30 mins every morning and night, using mostly quite streets with little traffic and a great choice of restaurants on my way home :-)

I'll post some pictures one day when I am taking the road and not hurrying to work.

2 March 2011

What's the next small thing?

Here's one small habit I adopted recently which had a big impact on my life in the area of procrastination versus getting things done. There's a lot of tasks --like repairing things in the home or doing one's tax declaration-- which linger on my To Do list way longer than needed. The longer things sit there, th harder I imagine them to be. Whenever I think of such an item on the list, the first thing that comes to my mind is "I don't even know how to start on this, how can I ever finish?"

Now the magic trick that helps me get unstuck in this situation is to simply ask myself the question: "What's the first small step that I need to do to advance this issue?" Here are some examples for simple steps: For the tax situation I might need to research a specific question on how to declare something. The small step could be to google it, or look it up in a book, or call the tax office. Or the small step could be to make an appointment with a tax consultant. In a home repair issue, the small step might be to buy a specific replacement part or to write down the exact measures of the part needed. Usually this small step seems minuscule and I might have avoided it because it seems like a lot of effort already just to make a small step. But if I verbalize this step and make it a To Do item of its own, then it will be easier to do, I will plan a time when to do it, and after doing it, I get the feeling of checking off an entire item from my list. After checking off this first small step, I'll feel more optimistic about the entire issue at all and might even be motivated to do some more work on it without planning the individual steps.

On issues that are truly hard, there will be several points at which I get stuck and won't get moving without some investment of self-control. In each case, I just ask: "What's the next small thing to get done?" and this item will provide me guidance on the larger part. It doesn't feel well to be driven by such small-scale To Do list items --I really would rather like to work freely and intuitively, which works really well for me, even on complex tasks. But for some issues, the intuitive way just doesn't work and then the small-scale items is exactly what's needed to get things done. It's not getting things done pleasantly, or creatively, or liberally, but it gets things done without the pain of high-fee overdue notices or looking at unfinished tasks for months. In fact, it is giving up a little bit of liberty ("Today I need to get this small thing done.") to gain a much larger liberty -- namely a life without big dreading unfinished items on one's lists, in one's life, and on one's mind.

I think the reason why this works so well is that it connects the benefits of the larger goal (getting rid of taxes, kitchen tap not dripping any more) with the small effort and quick accomplishing of the small step. I won't get done the large problem with a small step, but I can feel getting closer by my own effort. That feels good and is effective.

I have used this tactic several times in the past weeks after reading about it in the book "Switch: How to Change Things When Change Is Hard". It's a really good book, with many good lessons and I think this is only the first one with profound impact on my life.