Winter's toll. And a winter bike?

Winter is far from over here in Montreal. But because of a snapped gear cable I decided to do a spring tune-up on Wolfgang, my all-purpose, all-year bike. A lot of people have "winter beaters," but to me that never made too much sense: I really like my bike and don't see the point of riding an inferior quality bike at a time that places the highest demands on bike and rider. Especially, I wouldn't want to give up on my hub generator and LED lighting at the darkest time of the year. So far, this has worked well for me and the wear and tear of components didn't seem to be particularly bad. But somehow this winter seems to have been worse than previous, if not in weather but in damage to parts. My rear rim was destroyed a couple of weeks ago, after less than 10 000 km.

Busted rim

And during my tune-up today I discovered a whole bunch of other issues:

• my bottom bracket feels noticeably grindy
• the front brakes, Avid Single Digit 7, didn't turn that well around the brake bosses
• the Tiagra front derailleur is sticky and doesn't want to go to the smallest chainring any more
• all the cables and housing are in miserable condition and have to be replaced
• a lot of the bolts, despite being made of stainless steel, show a lot of surface corrosion
• one of the Shimano M424 pedals feels crunchy in the bearings

I'm not quite sure why this winter has been worse than others. I might have ridden more (last year I didn't ride between mid-January and the end of March because of a broken wrist), Montreal winters might be somewhat harder than those in Ithaca, and in some cases it is probably just accumulative damage.

This can't be good for your bike, can it?

It seems tempting to add a dedicated winter bike to the stable, and if I had the resources (and permission from the accomplice) I would probably get a bike with the following features:

• dynohub and lower quality LED lighting (e.g. the B&M Lyt): As stated above, I wouldn't want to give up on my dynohub-powered lighting system. However, for riding in the city I don't need a B&M Cyo or Philips SafeRide light. It's more about being seen than about seeing.
• frame with upright position: A frame that allows me to ride in a more upright position would help in snowy and icy conditions.
• SPD-compatible pedals: I also wouldn't want to give up on SPD pedals and I'm happy with my Lake winter cycling boots.
• plastic saddle: Whereas for long rides a leather saddle is an absolute requirement, for commuting a plastic saddle will do and also take care of the issue of having to cover your saddle---this season I managed to lose 3(!) saddle covers.
• drop bars: A lot of people prefer straight, Albatross, or North road bars for a winter bike; this makes sense from a balance and control perspective; however, my wrists are not built for any kind of non-drop bar, even on reasonably short rides.
• good and wide studded tires: Wheel size is not particularly important for me but good studded tires are a must. And some wideness helps with floating over snow.
• disc brakes (at least in the front): Rim brakes with drop bar levers can be pretty problematic in wet conditions, and most of the time winter means wet roads. Therefore I want disc brakes, probably mechanical ones like the Avid BB7 because of the drop bars. In addition, rim wear is not an issue with disc brakes.



Not a good studded tire

• 2-speed Sturmey Archer Duomatic kickback hub with low gearing: I'm not a single-speed or fixed gear person because my knees don't like me mashing up hills (and hills I like!); at the same time, derailleur systems don't particularly like road salt and constant wetness. A 2-speed Sturmey Archer kickback hub thus would be perfect: no cables, allows to use a 1/8" chain, and has more than one gear. I've never ridden a Duomatic hub so maybe it's not as good as I think.

I don't really see me building up this bike any time soon. But one may dream while wainting for spring...

Measuring the SP PD-8 hub

UPDATE January 2015: You can now find a technical drawing with measurements here.
CORRECTION: Please note that an earlier version of the post claimed that the center-to-flange distance is 32mm. I've corrected that to 22mm. Sorry for the confusion.

I'm getting read to build up new wheels with my recently acquired dynamo hubs. In my previous post, I had posted the manufacturer's stated dimensions, but I realized that they only provided the pitch circle diameter and the flange diameter--the latter being irrelevant for determining spoke length--but not the center-to-flange distance and also not the spoke hole diameter.

The best instructions for measuring a hub come from Roger Musson, author of a popular book on wheelbuilding. Fortunately, he has made this part of the book freely available. All you need to take the relevant measurements are calipers and a ruler. Musson suggests to drill a piece of wood, so that you when you insert the hub's axle the wood will be flush with the locknuts. If you're building a lot of wheels this probably makes sense. As an alternative, you can just measure from the end of the axle and then subtract the easily measurable distance between axle end and locknut. Then use the ruler to measure the distance between the wood/axle end and the inner side of the lower flange (what Musson denotes as x). Then turn around the hub and repeat the measurement on the other side, giving you the y value. With the SP disc hub that's a bit tricky, as the diameters of the two flanges are different. Musson's suggestion is to use a small piece of cardboard, mark it, and then measure on the cardboard. I was in a bit of hurry and thus just eyeballed it with the ruler after seeing that x and y would likely be the same for this hub. X and y are not the actual values needed for calculating spoke length, but they allow you to calculate the desired value by subtraction from half of the over-the-locknut dimension of the hub, z in Musson's system. On modern front hubs for regular bikes you don't really have to measure this, as it is a standardized dimension at 100mm. For the PD-8, x and y equal 28mm (32mm-4mm for the distance from axle end to locknut), yielding a center-to-flange dimension of 22mm on each side.

The flange diameters can directly be measured with calipers. Just make sure to measure from the centers of the spoke holes. The PD-8 comes out to 52mm and 58mm. The spoke hole diameter is a bit tricky to measure: The inside jaws of regular calipers tend to be too big for such small holes. I measured 2.7mm, but as most hubs use 2.5mm holes I'm assuming this is a measurement problem.

Now you can plug your values into the spoke length calculator of your choice and voilá! I recommend Karl Stoerzinger's Freespoke or the DT Swiss calculator.

First impressions: SP Hub Generators PD-8 and PV-8 (updated)

Wouter Scholten's website is a great resource for all hub generator lighting issues. He extensively tests almost all models of hubs and lights on the market in real world settings, and he is also unusually well-informed with regard to the introduction of new products. A while ago, he wrote about a new player on the hub generator market, Shutter Precision Ltd. from Taiwan. As the name implies, they started as a supplier for digital cameras and then later moved into bike component manufacturing. While the company itself has little name recognition, they are (presumably) the suppliers for two better known companies, Velo Orange[1] and Supernova.

After having introduced their switchable dynamo (in my opinion a solution in search of a problem), at the 2011 Taipei Cycle Show SP announced what would be the lightest generator hub, the SD-8 (disc brake)/SV-8 (rim brake). These two hubs, however, only are rated to a power output of 2.4W in a 622mm wheel, making them not street-legal according to the German StVZO requirements. However, they also announced a slightly more heavy model rated at 3W, the PD-8 and the PV-8. The technical specs and the prototype tests by Wouter sounded promising, and when Wouter's shop, Gambiet Fietsen, offered them for pre-order in September I went in for two generators, one disc, one rim. The disc one will replace my Shimano DH3-N80 on the Cross-Check which I unfortunately messed up while trying to re-grease the bearings, and the PV-8 will be part of a second front wheel for Gunnar, finally allowing me to turn him into a real brevet bike.

The hubs arrived yesterday, at a total price of 180 Euro shipped. The actual wheelbuilding will have to wait for a little while longer, but I wanted to share some pictures and impressions.

PV-8 in its original packaging. I'm not sure if all the color and spoke count variants are or will be actually available.

The hub looks quite similar to the current SON 28...

...but it does have the same terminal as Shimano hubs

Here you can see the German K-certification wave, making the generator street legal in Germany

The weight pretty much exactly matches the claimed weight.

Both the disc and non-disc version of the hub match their claimed weight of 390 g and 410 g, compared to 440/460 for the new SON 28, 490 g for the Shimano DH3N80, and 399 g for the Supernova Infinity S (center lock disc mounts). Only the SONdelux at 390 g (rim) and 395 g (disc) can match this, but at a significantly higher price point.

SP claims that the new generators do not only excel in weight, but are also "the most efficient" generators (this refers to the 2.4W ones) and their product sheets has a couple of graphs that show the generators to be more efficient than the SONdelux. I'm somewhat skeptical about those claims and am very much looking forward to some independent testing.

Measuring the dimensions of the hubs is a bit tricky with the tools I have and I've only been able to find the manufacturer's numbers for the 2.4W version. Probably they're going to be the same for the 3W, but I'll confirm this with Wouter or measure myself. The bearings are sealed cartridges and I'm not sure if they are user-replaceable.

I think that's all I can say for now. Once I have the wheels built up and ridden them a bit, I will post an update.

Update 2011-12-16:
In the meantime I've found the website of SP's distributor, and their catalog lists the relevant dimensions as follows:

	PV-8	PD-8 (non-disc/disc side)
Spoke P.C.D.	52mm	52mm/58mm
Flange diameter	60mm	60mm/66mm

They also have "replacement instructions" on their site that might contain instructions on how to replace the bearings. Unfortunately, the document is corrupted, though, and can't be opened. I've sent them an e-mail and we'll see if I hear back.

[1] If I remember correctly, the Velo Orange switchable dynohub got some bad reviews. At any rate, they no longer seem to sell it.
[2] There is also a 2.4W version, called SD-8/SV-8, suitable for those on small-wheeled bikes or those who don't care about the extra power/street legality in Germany.

New dynamo front wheel

As a Christmas present for my accomplice, I wanted to build up a generator front wheel for her Fuji Touring. I bought the Shimano LX generator hub from Germany for a pretty good price and got a Mavic A319 front wheel and DT Swiss Champion 2.0 290 mm spokes from my LBS. Last night I finally built up the wheel and it went pretty well. It's definitely easier the second time, and my tensiometer helped a lot, too. Once I find a cheap Ultegra hub on ebay, I'll build a new front wheel for Gunnar...