Showing posts with label shaft drive. Show all posts
Showing posts with label shaft drive. Show all posts

Saturday, July 12, 2008

A Little Update on the Bike

I recently received a comment from Jeff on my review of the Dynamic Crosstown 7 bicycle. (Amazingly, SiteMeter tells me that page is consistently my best draw, followed by my visit to Mellow Johnny's. Go figure...) Jeff was influenced in part by my review to take the plunge on a shaft driven bike, and he has outclassed me entirely by setting up a whole website to detail his experiences. His complete honesty has shamed me somewhat and caused me to realize that I'm a little guilty of something we might call "wishing away buyer's regret." That is, having plunked down a fair chunk of change for the bike, I'm determined to like it, facts supporting or no. Jeff has been undeterred by the size of his investment and freely given vent to both frustration and praise for his bike. Why would I not learn a little from him and share the good, the bad, and the ugly? Besides, I'm approaching 4000km (2400 mi) on the bike, and it's been almost a year since I bought it, and that's far enough for a pretty good assessment of long-term issues. 
First of all, the drive-line. Now that I have the gear greasing figured out, it's pretty much transparent. I just don't notice it. I can ride 500-600 km between shots of grease, and this is not an issue for me. In fact, it's a big advantage. I really don't miss chain maintenance. At all. (If you read Jeff's site, you'll find he's greasing every 75 mi or so, which to me seems way too often.)
My main drive-line complaint comes intermittently on hot days when I get a "tunk" sound once per pedal revolution when my left crank is straight up and down. Faster cadences make it louder than slow. Light pressure and very hard pressure make it go away, and if the temperature is below 90°F, I don't hear it.  It's always over 90°F in the summer in Austin, and I only get about half the time. Although it's only a minor annoyance, I wish I knew what it was.
Build quality. It's a little late for me to talk about build quality since I already mentioned the state of the wheels on receipt, but I did purchase a Park TM-1 spoke tension meter and tuned up the wheels. This is a necessary item of maintenance anyway, and I probably should have done it 2000km ago, but it feels like a new ride now, and I'll make this a regular date with the bike in the future. Regarding build quality, everything else is holding up well, and no other defects have come to light.
One last unspoken complaint relates to getting the driveline. This may seem a little obscure to all but the few Dynamic-owner readers that I have here, so feel free to skip on by if you want. Early in my setup, I was having trouble with grinding gears that turned out to be a problem of sorting out the proper kind of grease to use. During the process, though, I found I could make a big improvement to the feel of the drive line by adjusting the number of spacers on the rear axle. These are thin shim-stock washers that go between the hub and the drop-out to properly align the bevel gear with the drive shaft. The bike came with three fitted, and I improved the feel of the drive line noticeably by removing two of them. Later, the teflon-based grease solved the rest of the grinding problem, but I recently put them back in, just for kicks, to see what would happen, and I had to pull over and take them back off because the drive train became rough and the friction increased. I'm guessing that my gear set has probably worn in to its current arrangement and that putting them back in a long time ago wouldn't have had the same effect. Again, this is minor, and probably only of note to anyone else searching the net for information on shaft drives.
So I set out to try to complain a little bit about my bike, but I've ended up dismissing all of my complaints as minor. The fact remains, I like the bike, and I don't (honestly now) regret choosing it over a more conventional one, even after 4000km through Texas heat.

Tuesday, February 5, 2008

Dynamic Crosstown 7: A Review at 1200 miles

Last summer, I had to retire my old faithful commuter with something like 12k miles because it need about $400 worth of new drive train, wheel, hub, etc. Having paid about $400 for it 12 years ago, it was time to check out the market and replace it with a new bike.
I looked around at several options, and I ended up choosing the Dynamic Crosstown 7 over the Bianchi Milano, Bianchi Bergamo and the Breezer Uptown. This time around, I wanted reliability, low maintenance, and a good balance of cruising speed and comfort. Having had enough of cleaning dirty derailers, I was sure I wanted to get an internally geared hub. I ended choosing the Crosstown 7, a shaft-drive bike with the Shimano Nexus 7 internal hub.
I made my choice based on rides of the Bianchis at Ozone Bikes and reading the reviews of the Dynamic online. BikeCommuters.com gave a good review on their site. Many of the people who write in to the Dynamic website are hard core year-rounders in the sticks of Maine who ride through snow and summer rain alike. I took that to be a pretty good endorsement. The shaft drive had strong appeal to me since I have long ago tired of sprocket tattoos, greasy fingers, chewed up pants legs, and expensive drive train replacements. The shaft drive has no exposed moving parts, does not need to be cleaned, and is an $89 part when and if I have to replace it. (Dynamic estimates its lifetime at about 10k miles.) How many chains, gearsets, and derailleurs have I been through on my previous bike in 12k miles? At least $300 worth... :-\ Daring to be a little different, I took the plunge.

The buying experience was good overall with minor hiccups. Since they are fairly small volume, there are not local dealers, and my order was over the phone but the sales rep was helpful, knowledgeable, and willing to customize the order. They swapped the cheapo pedals and seat for a good cycle computer, and I added fenders, too. With the added delivery charge, the total came to about $750, delivered to the door. Their website estimates 3-5 days delivery to Austin. I ordered late on Friday, and it took them until the following Wednesday to put it in the mail, and five business days later (Monday) it arrived. From order to arrival was actually 10 days.
Assembly was straightforward: the shaft drive poses no special difficulty, and I was eager to take it for a spin. I noticed right away that the shaft drive was not silent but growled a little bit, especially right before shifts. Otherwise everything felt good.
I did quickly develop two beefs, though, that are pretty much inexcusable for a bike of this cost. First, out of the box, the front wheel had a wobble large enough to brush the front brakes. >:( I cured this with a spoke wrench and wheel alignment rig, discovering in the process that three spokes were way loose. How this got past quality control, I have no idea, but this was a disappointment. ??? The other beef is that the crank was a little loose and creaks embarrassingly when I stand on the pedals. :-[ This has been largely resolved by using clipped pedals and shoes (no switching torque direction) and a quick tightening of the crank arms, but I would expect the cranks to be appropriately seated and tightened to avoid the noises. Again, this is minor and relatively easily fixed, but with no local dealer offering a free first tuneup, and for the price I paid, I would expect it to be ready to go straight out of the box. :(
In any case, that was 1200miles ago, and quickly forgotten. I have five months riding it, in cold weather and hot. I've changed flats, and spent a lot of time in the saddle (The trip computer estimates about 100hrs.) So here are my well-worn impressions now:
In Re: the growling, a shot of grease to the front crank case completely solved the problem. I would have expected it to be done more thoroughly out of the box, but this was not a big deal. Properly done, it is totally silent. The bevel gears and drive shaft add a very small amount of friction relative to a brand new chain, but I think this would reverse for an older chain, and as I expected, the drive has gotten smoother with after a short break-in. On average, I've been adding grease to the front crank on a more or two less monthly basis. I ride a lot and more vigorously than some, so my greasing interval is slightly shorter than the recommended by Dynamic. I can tell it's time to add grease when the drivetrain gets a little growly. It's really very easy to do and takes me all of 15 seconds to do, so this is a HUGE improvement over the messy chain cleaning process I used to dread.
I definitely enjoy the lack of worry about pant cuffs, grease marks, and having been through the rain a few times this week and have not at all missed needing to clean the chain and derailleurs, etc.
I love the Nexus 7 hub, and highly recommend it: the shifts are precise and instantaneous. The gearing is well suited to my commute, which is moderately hilly (mostly along Shoal Creek from Anderson to campus). Anything hillier, and I'd recommend the 8-speed, whose extra gear is at the bottom of the range, for climbing. It took a little bit of time to reprogram my muscle memory since its grip shift is setup in the opposite sense from a derailleur's. I.E. twist forward to shift down and backward to shift up. At first I had to think about; now it comes naturally. Regardless, I love the ability to shift without pedaling, a huge help for hill starts.
The geometry is, for me, the right compromise between being far enough forward for speed and power but upright enough not to stress my wrists and lower back (especially with a backpack: I prefer not to use a bike rack). I saw a complaint online about the aluminum frame being too stiff, but I find it very comfortable and not too jarring, and I appreciate the lighter weight. In addition, the aluminum frame displays some beautifully well done TIG-welds, for those who appreciate that sort of thing.
Regarding flats, it's not a big deal to remove the rear wheel, although it is certainly more of a process than on a bike with a chain and quick release skewers. I keep two extra tools that I would not otherwise: a stubby flat-head screwdriver, and a thin wrench to fit the bolts on the rear axle. The main problem with getting the rear wheel off is actually the fenders. With the rear-open axle drops, you really have to remove the fender to get the wheel off. That makes it more involved than a conventional setup, so in order to minimize that problem, I replaced the Kendra tires it came with with some Maxxis urban tires with a Kevlar lining (and a reflective sidewall). Since putting on those tires, I've not had a single flat, and removing the rear wheel hasn't been an issue. Better tires are an option that Dynamic offers, and I would recommend paying the extra money for them.
Overall, I'm pleased with the purchase and would characterize it with one word: smooth. I look forward to putting lots more miles on the bike. In general, the build quality and components are good (with the above noted exceptions), and the Nexus 7 really shines. The shaft drive is pretty transparent and noticeable only because of the annoyances it doesn't give. I think I'll appreciate it more and more as I don't have to tune it, oil it, clean it, replace it, or hide my greasy pants legs. I hope that shaft drives become more accepted in the mainstream in the future. I think that would be well justified, especially among the bike-as-transportation community.