Fallbrook Technologies stellt die neue stufenlose NuVinci N360 Getriebenabe mit 360% Übersetzungverhältnis vor, die lt. Hersteller mit nun 2450g um 30% leichter als das Vorgängermodell ist. Details liefert die verlinkte Herstellerwebseite. Über den Wirkungsgrad finde ich wie schon beim Vormodell keine Angaben, und das Gewicht ist nach wie vor relativ hoch. Für Fahrräder ohne Leichtbauanforderungen oder für Lastenfahrräder ist die Technik auf jeden Fall interessant.

Update: In der Newsgroup de.rec.fahrrad wurde mir dazu dankenswerterweise der Link auf den Fahrbericht in phil’s velo blog genannt.

There are several solutions for two child seats on one Big Dummy. Here is mine with two child seats bolted on the snapdeck safely. See my previous articles on mounting the first child seat. It worked similar with the second one.

The longtail bicycle has not been used for quite some time now due to salted roads everywhere. I am currently using our winter MTB with studded tires mostly. However, here are some pictures showing the Big Dummy with the new SON 20R dynohub wheel installed, that I built previously. The new front wheel is completely identical to the previous one except for replacing the previous SON 28 dynamo hub by the new and lightweighted SON 20R centerlock hub as shown in image. The previous front wheel has been installed at the winter MTB.

Finally I received missing Sapim Force spokes of length 254mm in black colour and built the new Big Dummy front wheel with lightweighted SON 20R dynohub and strong Spank Subrosa rim in chocolate colour. This time I took some pictures showing the building process which should pretty much follow Sheldon Browns guidelines with 3 crossings. Leading spokes run at inside at outermost crossing to maintain better tension at trailing spokes when braking hard with disk brakes.
The resulting wheel should be very strong. It has got 1197g of weight (including rim tape, without quickrelease axle). That appears quite ok for a durable disk brake dynohub wheel. The new front wheel will replace my current SON 28 / Spank Subrosa front wheel at the Big Dummy. The latter one will be installed at our winter MTB where it will replace an older Shimano dynohub wheel, making it easier to juggle lighting equipment between those cycles just in case. Also I can finally install my Shimano XT centerlock front disk rotor to the Big Dummy, replacing a cheap noname 6 bolt rotor. And last but not least, it will shave off another 200g of weight without introducing any compromise.

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Bicycle Holder Installation

Within the last weeks I have been gathering some practice with my new Garmin GPS, an Oregon 400t model. It was attached to my MTB, the Big Dummy, a motorcycle and a scooter. Finally I installed two bicycle holders, one at the Big Dummy and one at the scooter. I will need to buy at least two more of them. The Garmin bicycle holder for Oregon and Colorado models is simple and cheap, but it is not ready for hard bumps and impacts, probably dropping the device incidentially. Thus I had to feed in some layers of soft rubber tubing to prevent heavy shattering of device. While this was possible in an easy and efficient way at the scooter due to its thin handle bar stay providing space for a thick rubber layer, at the Big Dummy I had to keep my anti vibration layer quite thin due to thick 31.8mm handlebar. See images to compare both mounts. Nevertheless, I am hoping there is enough rubber to make it absorb hard shaking and keep device in place.
There are several GPS mounting systems available as like Bikertech customized, Ram Mounts, Touratech and probably lots more, most of them fairly well addressing the oscillation issue, but in my opinion they are way too big and heavy for my small vehicles, also quite expensive.

Power Source

Lengthy trips require some thoughts about GPS power supply. Batteries may be sufficient for one or at most two days of continuous use. Some battery charger will be needed most likely, since the Garmin would never recharge its batteries inside when plugged to some USB power supply.
Trying to avoid another battery charger in my baggage, I connected the Garmin to my hub dynamo via the JaweTec Bikecharger mentioned previously here. Basically this works, but it is far from being a perfect solution:

• With the SON 28 dynamo a continuous speed of at least 10km/h is required to provide enough power for the device. As soon as riding slower the GPS will start beeping and switch to battery if possible or just shut down.
• The charger is not recognized as a simple power supply. By default the GPS goes to mass storage mode when the charger is switched on. To prevent this, the devices USB interface needs to be set to Garmin Spanner mode, which means, for every short power outage one needs to confirm switching to GPS mode instead of mass storage mode at some popup window coming up with a nasty beep, again and again. Thats sort of cumbersome.

For the motorcycles there is no problem about power supply since it can simply be wired and plugged to the battery via some modified USB converter taken from my previous navigation device. Thus I can run it without any battery inside which is strongly recommended with offroad usage. For the Big Dummy I am still in search for a better solution. I may probably connect a special battery charger to the JaweTec charger and keep a pair of fresh batteries there, but actually I do not really like this, since it requires taking along too many small devices and batteries. I may probably just get a small and lightweighted charger and recharge batteries every night, leaving the JaweTec charger at home.
Another feasible solution would be the dynohub driven Zzing USB charger providing internal battery buffering (unlike the JaWeTec charger) for devices not being capable of USB charging. This way the Oregon GPS could be used totally without its batteries (keeping it lightweighted with better protection against bumps and vibration). However, the Zzing charger is quite big.
As to some readers comment the Australian company Pedalpower+ provides DC hub generators and several more interesting mobile power supplies for bicycle usage.
I finally decided to stick with my reliable JaWeTec charger and put some USB chargeable power buffer, called PowerTank by SwissBatteries in between the charger and the Garmin Oregon. I will give it a try and report about it.

After a nice small MTB slope today I had to clean the MTB and also the Big Dummy from previous rides’ dirt. I removed wheels at both cycles and decided to swap wheels between them just for the fun of it. Both cycles have got an Alfine rear hub and disk brakes. Both wheelsets use same type of rim and strong spokes. Different sprocket sizes are no problem due to usage of chain tensioner at Big Dummy. So, swapping wheels might be a good idea for Big Dummy offroad rides that will occur every now and then. Also, I very much like the look of these white Spank rims.

However, there is some trouble, as always. The Continental Mountain King 2.4″ tires won’t fit my fender stays. Fenders need to be removed, otherwise they are very likely to be torn into the nobby tires. Also, rear disk is only 160mm while Big Dummy rear disk is 180mm. So, disks needed to be swapped as well, which would be no big problem. But finally, the MTBs Alfine sprocket has been installed reversely, which means, chain line is not as narrow as with Big Dummy. This means, the Big Dummys chain tensioner would need to be adjusted differently for every wheel swap. All in all this looks like too much effort to me, so I may just change tires in case I need some offroad tread.

Schwalbe Fat Frank rear tire after 3000km of tarmac usage mostly, some offroad also. The brown dot is tread wear. There is no more creme coloured rubber there. To me that means, durability of those tires compares to narrow road racing tires.

Basically I think the BD setup with rigid fork is a perfect idea (and was exactly what I wanted). There is no need for suspension at the BD at least for my way of riding (touring on- and offroad, every day riding). However, I am experiencing two issues that I am a bit picky about.

1. Handling of my BD when riding turns: I have no idea whether this is a matter of tires, steering angles or fork specification. Surly setup looks perfectly alright. I cannot see any technical reason for this in frame geometry. Nevertheless, when riding fast turns with quite some slope, there is some sort of oversteering. Handle bar (or tire?) tends to take the turn harder and harder forcefully, no matter whether applying brakes or not. My BD does not just run through the bends in a neutral way as one would expect (my MTB or road bikes handling keeps neutral when riding turns with slope). I have not yet experienced such behaviour with previous bikes, regardless of tire thickness, but I have never been using Fat Frank tires with their special shape before. I have got an 18″ frame using a dainty hope headset keeping front low.
2. Combining rigid fork with disk brake: Apart from quick release axle issue, (see disk brake page) there is some more thing I would like to point out. When using brakes under certain circumstances fork might start building up oscillation in longitudinal direction somehow. Something I have never realized with disk brakes up to now, even at some previous rigid fork setup in another bicycle. It happens when braking on ripples or when using brakes in turns and trying to modify the curve radius. These actions will be taken up by fork which will start swinging back and forth (at least it feels as like), and brake lever needs to be released to calm it down. It is not just like using brakes on uneven ground, as like everyone is used to with ordinary MTB riding or so. In my opinion this may be a matter of rigid fork not being able to vertically absorb initial strong brake impulses on the one hand and riding impacts on the other (concurrently), making it start to oscillate. Maybe this is a matter of thick tire springiness lacking any dampening. Within the last 2600km of BD riding I had it twice, both when riding downhill tarmac roads with nearly no load. Second experience happened today in the morning when I took a tight turn with brakes applied and had to go even tighter which let fork start shaking.
   Brakes (2008 XT hydr. disk) provide strong, clear and smooth operation. There are no noises at all, no vibrations, nothing. Also, there are no issues with irregular brake power, bad rotors or anything.

I am currently thinking about testing my pace RC40F suspension fork (130mm of travel) at the BD to address both issues. It might absorb or dampen sharp braking and riding impacts and could probably prevent what I called fork oscillation. Also it will considerably change steering geometry and thus could resolve handling issue. However, these issues may very much be related to the tires used, so I should probably start experimenting with different tires as a first step.

Today the installation of Medion MD96050 (PNA465) navigation device was finished and tested. The Medion PNA is connected to the JaWeTec USB charger (see previous post) and powered through the dynamo hub (6V/3W). It works well. Charging starts at riding speed of 7 km/h. When lights are switched on additionally, it starts charging at 12 km/h. USB charger can be switched off easily. The PNA together with the USB charger can quickly be removed by unplugging power supply cable.

When testing the whole arrangement rolling up and down our street an hour ago, a bicycle traveller with lots of baggage and a bob trailer came along and we started talking about bicycles. He turned out to be the owner of the well known bakfiets cargobike distributor Beer Transport Fietsen in Den Haag. Due to my previous web research concerning big dummy related stuff I knew the shop. It was very nice to meet you and your family here. Have a good trip and lots of sunny rides!

Today I received the JaWeTec USB charger for dynamo hubs as like SON or Shimano DH-3D71 or Alfine or similar. This is a small box with an ordinary USB type A connector which provides 5V of direct current and 500mA, which should be sufficient to feed any USB charged devices according to USB specification. It is protected against overvoltage up to 50km/h as to manufacturers documentation and may switch off automatically at extreme voltage or heat. The little box has got 50g in weight approximately and can easily be removed from bicycle by unplugging its connector in the dynamo cable. The box unfortunately is not water resistant. I will attach it at downside of my Medion PNA and put the complete unit into some transparent plastic bag.


The chargers power supply cables had to be soldered to the original cables of my edelux headlight. I opened the protective coating around the dynamo connectors, made a soldering joint for each of the two wires and put new shrink hose around each connector. The charger cable runs along the speedo cable up to the handlebar where it can be connected to the box which will be installed together with the navigation device is mounted.

Update: unfortunately the Jawetec charger is no longer available as to my knowledge.

The new headlight was installed two days ago. It is small and looks cute with its black aluminium jacket. When using the built in twilight sensor, it will be engaged most of the time, since it only switches off when being exposed to sunlight, so this should be slightly adjusted by manufacturer. Nevertheless, it can be switched off manually. There is a yellow-greenish gleam in the LED beam when turned on, which reminds me at unreal tournaments plasma gun. This sort of light colour may improve sight at night, according to manufacturer.

After finishing the basic build up, one of the next steps was the installation of a child seat. Since I will never use seat systems mounted to lightweighted thin walled frame tubes, my idea was to take a simple plastic seat without its carrier tubes and fix it to the snapdeck directly. For detailled information see bottom of this entry and comments at images.
Note that in some countries using a full seat with head and leg support may be mandatory by law. A child seat may need to provide full coverage of complete child body. A simple wooden seat placed on top of the snapdeck like shown on many pictures -although looking nice- might compromise legal riding, depending on local rules and laws. In some countries, as like Austria, it is even prohibited to take more than 1 kid out on one bicycle, but maybe there is a way around this by referring to some European laws.

Get a simple bicycle seat, where plastic seat can be separated from any mounting tubes used to fix seat to ordinary bicycle. My seat has got two U-shaped bolts fixing it to its platform or its carrier tubes respectively. Now, there are mainly two issues that need to be resolved.

1. The seat needs to be located rearmost possible to avoid collisions between childs feet or seats leg parts and riders feet when pedalling. Thus, I had to modify the legs of the seat to be able to slide seat backwards as far as possible. Without this modification there would not be enough space for V-racks inside the seat.
2. Snapdeck needs to be installed safely by use of straps or whatever. Since snapdeck normally is just losely mounted to V-racks, strong straps need to be used to keep it in position, fix V-racks to each other holding snapdeck closely and prevent it from sliding in forward direction when braking or going downhill. Always avoid riding hard bumps or sudden movement of bicycle with kid placed on back seat. Up to now there have been no problems so far, even when riding offroad or out of saddle.

The Pea Pod seat available at Xtracycle should be installed at Big Dummy by use of included stays, fixing it to V-racks and some frame tube (which I tried to avoid here). This way, it gets located in an elevated position such there is not collision when pedalling. On the other hand, this gives bad impact on bicycles balance point due to the high positioning of seat. Also the Pea Pod appears to be quite expensive in Germany, if at all available.

An Article at the Xtracycle blog mainly discussing the Xtracycle pea pod child seat features this image with some additional words on the special platform mounted on the V-racks, replacing the snapdeck, called TekDeck. According to the text it will be released later this year. A very good idea in my opinion since it keeps V-racks attached to each other by use of wide clamps not interfering with nylon mesh. Mounting the snapdeck may become a bit of troublesome when placing it on top of the nylon loops dislocating them backwardly.
Also, it looks quite lightweighted and small, while the snapdeck is unnecessarily heavy for sporty touring, I think.

I probably want to write some words on fixing an ordinary child seat on the snapdeck. Basically this is the only way at all that I am using my snapdeck, quickly mounting it for riding with kid and dismounting it afterwards.

Basically the BD frame builds up straight forward without any concerns or caveats. Get yourself some long cables, liners and wires and start. Here are just some small issues I encountered when building up the big dummy at home. Please have a look at Surly Spew for the real important topics of it.

Disk brakes

• When using disk brakes, take care you can get some rear brake tubing of probably 190cm in length. Magura offers up to 250cm, Shimano does not. With my 2008 Shimano XT disk brakes I had to use replacement tubing. I had a 250cm Magura liner in my toolbox, so I cut off Maguras fixed end and installed both ends with Shimano olives and Shimano hex nuts.
• At my forks IS2000 clamp, the Shimano caliper needed some more radial offset since there was not enough clearance between disk and caliper. Luckywise the caliper uses postmount standard and therefore I could insert some spacers between caliper and postmount adapter. I have no idea how this could be fixed with some IS2000 caliper.
• Take care for freeloader bag! Put some protective material at the inside of the left freeloader bag, where it hits the caliper. At long downhill sections it might get too hot for the nylon material. Or better use the quite expensive Xtracycle disk mount kit pretty well pictured in this nice BD build to protect freeloader bag from hitting any hot brake parts.

Tires and fenders

• Surly permits use of 2.5″ tires. With Schwalbe Fat Frank 2.35″ I realize there is enough lateral tire clearance, but it gets very tight at the rear end of the frame since this type of tire has got quite a high profile. Maybe this is the reason why it offers great riding comfort while being quite fast on the other hand.
• Mud catchers: frame and fork offer several thread eyelets for different purposes. I use SKS Bluemels, ATB version. These are lightweighted adaptive mudguards made from plastics fitting most 26″ bikes. Tire width should not exceed 2.25″ according to SKS, but it fits 2.35 Fat Frank tires on 30mm wide Subrosa rims as well, as shown in picture below. There is not much clearance in between, but it works. At the left side, I cut away one of the holding stays since it collided with brake caliper. It would easily be possible to mount it above the brake caliper since there are some more eyelets, but I decided to leave those for later usage. Front guard mounting is visible in the picture to the right. Take care there are safety clips installed at the front fender stays allowing them getting ripped off from eyelets, to avoid wheel blockage in case some stuff gets in between tire and fender.

Drive train

• The BD can be driven every way you like, but I prefer internal gear hubs. While Rohloff is too expensive, NuVinci is very interesting but too heavy and SRAM i9 is too heavy compared to Alfine, I chose Shimano Alfine 8 speed hub (1600g) with a 20 teeth sprocket. This hub is quite cheap, looks nice, seems to be durable and fits the frame, although the dropout slots are a bit too small for the anti torsion spacers. It could easily be used in combination with a dual crankset and front deraillieur, since a chain tensioning device is needed anyway due to vertical dropout slots.
  Nevertheless, for me it works with single chainwheel and 8 gears, and I do not even need a long shifting cable since Shimanos standard length of 210mm will fit by far. I believe it is nice to have only one cable instead of 2 for Rohloff or NuVinci, just for simplicity. Removing the rear wheel is slightly more messy, on the other hand.
• Although being 173cm in size, I am using short cranks of 160mm length. At the BD this is of advantage due to low ground clearance when going slopes and riding offroad and bumps. I may recommend Token bottom brackets made from carbon and steel. These are lightweighted and up to now appear to work completely silent without any cracking noises. In Germany you may get them for instance at Radplan Delta together with fine and lightweighted cranksets from TA Specialites or Sugino or many others. With a 34 teeth chainwheel I am capable of riding uphills at 15-20% and even more, strongly depending on the load, and it is still possible to pedal at speeds up to 40km/h.

Xtracycle

The Xtracycle rack is mounted losely. There is no fixed connection holding it in place. Since I do not like the lateral sloppyness of the V-racks, I wrapped some tape around its exterior tube sections before plugging them into the rear frame extension. This way the V-racks will stay in place a bit better and sloppyness is reduced. Also, as suggested by Surly Spew, use sections of thin bicycle tube covering the connection sections to avoid water, rain and dirt getting into the frame tubing where V-racks are mounted.
Nevertheless, always use some strap to connect V-racks to each other, no matter whether snap deck is mounted or not. When riding out of saddle and swinging the bike laterally your load might behave badly otherwise.
I have mounted a child seat on the snap deck. When using it, I fix it by a strong strap connecting it to the V-racks and being pulled firmly. Also I have several leather pedal straps for multiple purposes as to my needs.

Bicycle electrics

To me it sounds very reasonable to put lighting equipment on a cycle like the BD. Apart from being obligatory in several countries, there is no way around it when riding at night. Since I do not like messing around with batteries, I installed a SON dynamo hub with LED rear- and front lights and firm 2 wire cabling. Everything works without batteries. There is light even when bicycle stops. The Xtracycle V-racks are a perfect place to mount a tail light and some reflecting stuff. The headlight is mounted at the usual location at the fork.