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Review: Dynamic “Crosstown 7” Shaft-Drive Bicycle

Dynamic Crosstown 7
The good folks at Dynamic Bicycles offered their “Crosstown 7″ commuter bike to us for testing. In many respects, it is like so many other commuter-oriented bicycles on the market — TIG-welded aluminum frame, mounting points for fenders and rear rack, upright riding position. Where this bike differs, however, is how power gets from the pedals to the rear hub. This bike uses a very clever and deceptively simple shaft-drive. Yeah, that’s right — no greasy chain, no chainrings to chew up your pants. In fact, Dynamic takes things a step further by mounting the shaft-drive to a Shimano Nexus Inter-7 internal hub. So, no derailleurs either!

The heart of the Dynamic drivetrain — the shaft-drive assembly:
The shaft-drive assembly

Here’s some of the specs, straight from the manufacturer’s website:

    -7005 Aluminum Frame, butted for light weight
    -Aluminum front fork
    -Alex DA-16 High Profile Alloy Rims (28-38C tires)
    -Kenda EuroTour Tires, 700×35C, 50-85psi
    -Dynamic Street Shaft Drive
    -Shimano Nexus Inter-7 Gearing, All-internal (17-gear range)
    -Shimano Nexus 7-speed Twist Grip Shift
    -Tektro Quartz alloy brakes; front disc brake optional
    -Tektro 2-finger Alloy brake levers
    -Base price: $679.00

The frame for this bike is unique: a narrower-width bottom bracket (BB) shell that is also larger in diameter from a traditional BB and elevated chainstays that are welded to the base of the seat tube rather than to the back of the BB shell. The elevated chainstays give room to mount the shaft-drive assembly. The rear-facing “track style? forkends position the rear wheel in the frame and align the rear hub’s spiral bevel gear with the rest of the shaft-drive assembly. Obviously, retrofitting this shaft-drive assembly to a traditional bicycle frame is out of the question.

Details of the unique frame:
Elevated chainstays and big, narrow BB

Bottom bracket clearance to the ground with 700x35C tires is a whopping 10 inches! And this is pure clearance, too – there is no chainring to catch on obstacles if a rider should happen to find him- or herself hopping over a steep curb.

Did I mention the paint job on this bike? In low light, it appears to be a dull charcoal grey. In sunlight, however, it shines with pink and blue iridescence…every bit as flashy and sexy as a Japanese keirin bike! For folks who like to keep their bikes on the down-low, the frame decals are applied OVER the clearcoat and are easily removable.
Here’s a picture of the headtube and the glossy paintjob…the photo doesn’t do this color justice!
Paintjob

The frame feels stiff…jarringly so. To be fair, this is the first aluminum-framed bike I’ve ridden more than a couple miles – I don’t know if aluminum bikes always transmit this amount of shock. The Dynamic frame appears utterly flex-free, and with the beefy, ovalized down tube, aluminum forks and 36-spoked deep profile rims, the ride felt harsh. Over two miles of my round-trip commute is over cobblestones, and it was pretty punishing! Perhaps a carbon fork and a suspension seatpost would have improved the “seat feel? of this bike and taken some of the edge off?

The parts specifications for this bike have high and low points. Tektro Quartz linear pull brakes are about the best “off-brand? V brakes money can buy; easy to adjust and tremendous stopping power. The Nexus hub is superlative – smooth and easy to shift and virtually maintenance-free. The front hub is a sealed bearing model made by Access. I am unfamiliar with the brand, but the hub is beefy and smooth, and comes disc-ready (Dynamic offers a front-disc brake upgrade for an additional $60). The Alex DA-16 rims are tough – real pothole killers! The handlebars and stem are workmanlike…nothing fancy. The saddle and pedals? Well, they suck. Saddles are such a personal choice that I wholly expected this “Velo Plush? saddle to be a pain in the ass, and I was right! Also, the pedals that come with the bike should immediately be scrapped in favor of something a little bigger and with more traction. Even with lugged running shoes, my feet slipped off the pedals a couple times in the dampness that is summertime Florida. Since this bike is meant for urban commuting and getting around town, BMX-style platforms would be ideal – and wouldn’t require dedicated cycling shoes.

Over the past month, I have ridden this bike over 100 miles to and from work and on a number of recreational rides. While I don’t have any way to quantify (with cold, hard numbers – this ain’t a physics lab) just how much more efficient a shaft-drive is as compared to a traditional chain-driven bicycle, I can say with confidence that this shaft-drive feels s-m-o-o-t-h. In fact, it is so smooth that it feels oddly boneless; chain-driven bikes give the rider a lot of feedback in terms of friction as the chain wraps around cogs, chainrings and derailleur pulleys. When I rode the Dynamic, the only sensation was that I could very faintly feel the bevel gears meshing against each other – in fact, the more I rode it the more I noticed it. It is DEFINITELY different-feeling than a chain-driven bike! Another perceived benefit of this shaft-drive is there is no “gear lash? or lag when pedaling – pedaling force is instantly and seamlessly converted to forward motion. On a chain-drive bike, there is always a bit of lag as chain slack is taken up by the derailleur springs and as the freewheel/cassette pawls engage. Not so with the Crosstown 7 – you pedal and GO!!!

The rear spiral bevel gear of the shaft-drive system as attached to the Nexus hub:
Rear bevel gear attached to Nexus hub

Standing on the pedals to grunt up hills was when this system felt weirdest – and when the nearly frictionless drivetrain was most noticeable (and appreciated!). The system is silent – the only noise it makes is some occasional faint ticking in certain gears, and that can be attributed to the Nexus hub, not the shaft-drive. This bike is STEALTH all the way! Shifting is a breeze – the Nexus hub is spectacular. I found myself shifting more often because it was so easy and smooth, and I found the range of seven speeds to be more than adequate for my relatively flat commute. For people living in more hilly areas, an 8-speed Crosstown model is available from Dynamic.

How much does the shaft-drive system add in weight to a bicycle? The manufacturer claims that the system adds less than one pound as compared to a geared bicycle, and this makes sense…after all, the entire assembly consists of four chromoly spiral bevel gears, a shaft and an aluminum housing. I think most people can live with an extra pound…and for the real weight-weenies out there, a few judicious parts swaps could help lose some of that extra weight.

Maintenance is, for the most part, a non-issue with this bike. I rode this bike in two heavy Florida summer downpours with deep puddles almost up to the hubs, and I never had to worry about a rusty chain. Dynamic recommends adding a shot of grease to the drive every 600-1000 miles. The shaft-drive comes complete with a zerk-type grease gun fitting…just attach your grease gun and squirt a bit in there. The manufacturer recommends Finish Line’s Teflon grease. I couldn’t find my grease gun, so I used a 12cc syringe with a plastic “gastric tube lavage? tip to inject 4-6cc of grease into the shaft-drive after removing the zerk fitting with a 7mm box wrench. The Nexus hub needs occasional cable adjusting, which takes all of two minutes, and the brakes could use some occasional tweaking. Is it ever that simple on a gearie?

No grease gun? No problem, especially if you know a medical professional with access to syringes:
Syringe replaces the grease gun

Are there additional steps when changing a flat rear tire? Yes, but the process only takes an extra 30 seconds from a traditional bolted-on or QR wheel. With a screwdriver, remove the two screws that hold the black plastic rear hub cover on. Slide the cover off. Pull the shifter cable sharply downwards to release it from the hub’s cable guide and detach the leaded end from the hook on the hub. Unscrew the axle nuts with a 15mm wrench, taking care to keep the unique washers on each side of the hub in proper order. Change the flat and reverse the disassembly process. Those special washers realign the hub with the tail end of the shaft-drive, so no fiddling is required to get things running smoothly again. Hell, it takes longer to write it out than to actually do it!

The “track-style” rear forkends and plastic hub cover:
The back of the bike -- hub cover

Does the shaft-drive wear out? Well, yes…eventually. Patrick Perugini, the president of Dynamic, indicated that the shaft-drive is rated for 6000 to 10000 miles (depending on frequency of greasing) before it requires replacement. And, a replacement assembly with all bearings is only $89.00, available directly from Dynamic. Now, compare that to a traditional geared bike – can you get 10000 miles out of one set of chainrings, cassette cogs and a chain? I didn’t think so! Can you replace two (or three) chainrings, 8/9/10 cogs and a chain for less than $89.00? Only if you really, really shop around!

Two gripes stand out in my mind: the first is the riding position, which is VERY upright. While this position gives the rider a commanding view of the streets, there is no place to hide once stiff headwinds come into play. As configured, the Crosstown 7 is really not suitable for long-distance fast commuting. I would love to see a drop-bar option for this bike (or would consider one of the road-bike models Dynamic makes if a more aerodynamic position is desired).

The other gripe is that while Dynamic inexpensively offers accessories such as a rear rack and fenders, at this price point I expect to see both of those included as standard features. Most similarly-equipped bikes from other manufacturers (and here I mean geared commuter bikes) come standard with rack and full-coverage fenders.

Overall, I think Dynamic has a winner with their Crosstown 7. It appears (and rides) in every way like the around-town errand, commuting and recreation bike it was meant to be, and you just can’t beat its low-maintenance features. No more greasy chain tattoos, tattered pants cuffs or dirty hands from a mid-ride tire change!

Hits:

    -low maintenance
    -smooth, effortless drivetrain and shifting system
    -sexy paintjob
    -lifetime frame warranty
    -perfectly suited for around-town cruising and medium-distance (5-12 miles) commuting
    -Dynamic’s sterling customer service – questions promptly answered and great website documentation for maintenance and service of these bikes.

Misses:

    -Stiff and unforgiving ride
    -Saddle and pedals must be swapped out immediately!
    -Upright stance gives some aerodynamic issues in headwinds

Visit Dynamic’s website to learn more about the shaft-drive – there is a great “FAQ? on the site – and to see other models Dynamic manufactures.

Redline 925 Long Term Review

People have been asking about a review on the Redline 925. I actually wrote one a while ago for another site. But here’s an update on how well the 925 has been doing in the past 9 months.

My Redline 925 went from this…

To this…

I took off all the fenders, guards, rear brake and replaced it with my custom bars, XTR brake lever and clipless pedals.

I’ve been riding the 925 for a long time now. In fact this is my first fixed gear bike and probably my last(because I’d hate to ride another fixie…).

For those of you wondering what the big deal about the Redline 925 is, well it’s this simple; the bike is really fun to ride.

No matter who ever tries out this bike, the all fall in love with it. Moe and Priscilla rode it and now they both want one! At the Ride of Silence, a couple of the guys there test rode the 925 and both claimed that the bike rode really nice. Another thing most people say about the Redline is that it has a “softer ride.” No, the tires were not low in air pressure. But the over all feel of the bike is very forgiving.

I’ve ridden road bikes before and they are harsh when it comes to the vibrations and over all road conditions that bicycle wheels have to roll through. But with the Redline 925, yes you still feel things, but it’s not that brutal. I suppose it’s the steel frame…you know what they say; “Steel is Real!” That saying might just be the ticket to why this bike feels so good.

The 42×15 gearing allows me to fly on the flats and even climb some of the local hills in my area. I’ve yet had the desire to change my gearing on this bike because of the fact that it’s I’m neither spinning too much nor having a hard time spinning. This gearing even allows me to stop skid easily…I’m getting better at it!

Another great strength the Redline 925 has is taking off the line at the stop light. I’ve had many occasions where I am waiting for a light to change and once it turns green, I mash on the pedals and zoom through the intersection. I remember pulling up to lycra wearing roadie at a light, I said good morning to him, he sizes me up and has this bewildered look on his face as he’s grazing over my bike with his eyes. The light turned green, I mash on the pedals and leave the dude behind…

To me, being able to dash out of an intersection rather quickly is a big plus. Sometimes you just need that boost to help you get your momentum up or to assert your place in traffic.

Problems:
None what so ever! I’ve yet to experience any mechanical problems with the bike. Well, actually I’ve had to true my front wheel once, but that was because I hit a pothole. As long as you perform basic bicycle maintenance, you’ll be fine.

Summary:
This bike kicks ass, and it’s totally affordable at $499! If you want a fixie/SS at a low price, then get the Redline 925. You will NOT be disappointed! Oh and one more thing, I LOVE their logo…


Seal Line Urban Backpack Review

Seal Line, the makers of dry bags and packs for watersports enthusiasts, have created an “Urban” line of waterproof bags (backpacks and cross-strap shoulder bags) aimed at bicycle commuters, messengers or anyone else needing a rugged way to carry items on a bike.

The Seal Line Urban Backpack

The good folks at Seal Line recently sent me a large backpack to review. I’ve worn it on a few bike rides and have tested it in my backyard laboratory and am quite impressed. Here’s the manufacturer’s quick description:

-Volume: 2270 cu. in./37 liters
-Size: 10 x 14.5 x 23 in./25 x 35.5 x 58 cm
-QuickClip Closure
-Modular Accessory Pocket™ System
-PVC-Free 300D PU-Coated Polyester and Scrim-Reinforced Urethane
-External Pocket and Carry Handle

This bag is pretty cavernous — a large single compartment underneath the roll-down flap closure and a smallish external pocket with a waterproof zipper and rainflap protecting it. There is no internal organizer system…neat-freaks who like to keep their goodies organized need not apply. Here’s a shot of the inside of the bag:
The inside of the bag -- a really large compartment for swallowing up your goodies!

The bag’s shoulder straps and back panel are made of a dense, perforated foam covered in rubberized mesh. Both of these features increase ventilation. In addition to the shoulder straps, there are both waist and sternum straps made of nylon webbing with quick-release buckles. The waist straps tuck away into hidden compartments when not needed. Finally, there is a built-in web carrying handle at the top of the harness.
The harness system -- padded and ventilated

I loaded up this bag with a pair of dress shoes, library books, a couple of large towels and a few other assorted items and took the bag for a couple 8-10 mile rides. I estimated the load weight somewhere around 20 lbs. Overall, the bag was surprisingly comfortable — the harness padding works fine and an internal stiff plastic sheet against the back wall prevents sharp corners from digging into the wearer’s back. The harness system keeps the bag from swaying or shifting as I rode, even under high RPMs. I can’t say that about my current messenger bag, which moves all over the place even with tight cross-straps!
20+ lbs of load handled quite comfortably!

Despite the perforated back padding, you WILL get a sweaty back from riding with this bag — it covers so much of a rider’s back that “SBS” (Sweaty Back Syndrome) is unavoidable. Thank the stars this bag is waterproof, right?

And just how waterproof is this bag? Seal Line rates it as “watertight” — able to withstand quick submersions and able to float if dropped in the water. The bag’s seal is really quite simple. It consists of a stiff plastic lip on one edge of the opening and an elasticized “Quick Clip” closure that holds the bag shut. A rider simply fills the bag, presses out any excess air, rolls the bag’s top two or three times and engages the quick clip to seal it. It is a quick, ingenious and foolproof method of closure, and it will SEAL this bag!!! I filled the backpack with newspapers and proceeded to direct a high-pressure jet of water directly at the rolled seal and other parts of the bag. The bag shrugged off this onslaught, and when I opened it to check the inside, everything was bone-dry. VERY impressive!

Durability over the long haul shouldn’t be a concern. The bag’s material is tough stuff, and the seams are all radio welded over a wide margin. The materials and construction of this bag are top notch: tight, even stitching on the harness system; no odd puckers or sloppy areas anywhere on the bag.

Really, the only negative mark I can give this bag is that it is too big for my personal commuting needs –I just don’t carry enough stuff to justify such a large bag. This bag is probably better suited for high-mileage commuters and bicycle couriers who need a high-capacity bag — folks who have to carry a lot of stuff and be sure that it arrives safe, clean and dry.

Oh, did I mention this bag is B-I-G?
My handsome assistant -- 37 lbs. of love!

Check out Seal Line’s complete lineup…I am sure there’s a bag solution for almost every rider!