26 February 2014

Monkey Ride: Bike Friday with Belt Drive and Rohloff SPEEDHUB 500/14


Bike Friday built this frame for us to showcase at tradeshows as well as to offer to customers visiting our office wanting to test the Rohloff SPEEDHUB and Gates Carbon Drive drivetrain. Bike Friday hand builds each of their folding bikes to their customers’ specifications in their Eugene, Oregon workshop. They are the only U.S.-made folding bike-specific company, and they have built a devoted following for their craftsmanship and functional designs. Their goal of producing "bikes that fold" as opposed to "folding bikes" comes through in the handling of their bikes. We added a few special touches to make the bike stand out, including red anodized components and a custom build kit. The result is an ideal travel or commuter bike that is easy to fold up and pack into a suitcase or trunk of a car or take into an office or onto a subway train.


This bike is built around Bike Friday’s Silk frame, which was designed to work well with the Gates belt drive system. They offer the Silk frame setup for a variety of uses including road, touring, and commuting. Sliding dropouts adjust belt or chain tension, and 20 inch wheels are used as on most of Bike Friday's other models. The 20 inch wheels offer more comfort on bumpy roads and a more usable gear range than the 16 inch wheels they use on their commuter-specific Tikit model. The fold point for the rear end maintains the relationship between the crankset and the rear wheel so that the belt or chain will stay tensioned when folded.  The frame folds vertically around the bottom bracket, which results in a quick and user-friendly folding process. When completely folded up, the bike will fit neatly into a suitcase for easy travel.



While Bike Friday was building the frame, we sent a few components to our local anodizer to match them to the red color of the Rohloff SPEEDHUB and Schmidt SON28 hubs: front sprocket, rims, headset cups, Rohloff external gear mechanism cable box, and shifter housing. Once we had the parts back from the anodizer, we laced up the wheels using Velocity’s 20” Aeroheat rims with Sapim spokes and nipples for fairly light, strong and durability setup.


On most folding bikes, the shifting components are particularly susceptible to being damaged. The rear derailleur is one of the most delicate components on any bike, and can easily be bent or broken if it is bumped. On a folding bike in particular, the rear derailleur sits close to the ground due to the small wheels and is also exposed to being hit by the handlebars or front wheel during the folding process. It is also likely to be hit or damaged on a crowded commuter train with people filing in and out past the bike on the ground.

Additionally, small-wheeled bikes often use much larger chainrings compared to larger-wheeled bikes to account for the effect that wheel size has on the gear development. Front derailleurs are shaped to shift the size chainrings found on 26" or 700c-wheeled bikes, not the larger sized rings needed to maintain the same gear development on smaller-wheeled bikes. As a result, the shifting is usually slower and less crisp than is usually expected.

The Rohloff SPEEDHUB offers an optimal shifting system for a folding bike because the shifting components are all protected inside the hubshell and no shifting parts are exposed to being bent or damaged. It is also typically used only with one front chainring, so there is no impact on shifting precision by changing the ring size.

A conventional bike chain is also less-than-ideal on a folding bike because you're often coming in contact with the greasy, messy chain during the folding, packing, and transport processes. A Gates Carbon Drive belt requires no oil or grease, so your clothes and hands stay clean. This also means that no maintenance is required on it. Additionally, since the belts do not stretch, you get a service life that is significantly longer than with a chain - minimum twice as long and up to ten times as long depending on usage conditions.


We chose a variety of components that put the rider in a comfortable, ergonomic seating position. A custom Groovy Cycle Works Luv Handle handlebar with 45 degrees of backsweep mimics the natural resting position of a rider’s hands, Ergon’s GC1 grips feature a wide palm rest to take pressure off of the hands, and Selle Anatomica’s Titanico leather saddle is very comfortable right out of the box with or without padded shorts. We rounded out the component selection with Magura’s MT2 hydraulic brakes, which provide good stopping power and require minimal maintenance, and Schwalbe’s Big Apple tires, which feature a flat-resistant casing and large air volume to absorb the bumps.

When we took this bike out for a test ride, it felt very comfortable and handled much like a bike with larger wheels. It was hard for us to tell we were riding a folding bike until we looked down at the frame, which is the litmus test for any good folding bike. If you’re interested in the ideal folding commuter bike or would like to take this bike for a test ride, please contact us.

Build details:

• Frame: Bike Friday custom Silk
• Fork: Bike Friday
• Headset: Cane Creek Solo
• Stem: Controltech
• Handlebar: Groovy Cycles Luv Handles
• Shifter: Rohloff
• Grips: Ergon GC1
• Seatpost: Thomson Elite
• Saddle: Selle Anatomica Titanico
• Seat Clamp: Bike Friday
• Front Hub: Schmidt SON28
• Rear hub: Rohloff SPEEDHUB 500/14
• Spokes: Sapim Race
• Nipples: Sapim Brass
• Rims: Velocity Aeroheat 20”
• Tires: Schwalbe Big Apple 20x2.0”
• Cranks: Middleburn

14 comments:

  1. Drool...this is beautiful...and exactly what I want...

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    1. Give us a call if/when you're ready to order and we can make it happen :-).

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  2. Hi Neil, CM; I was wondering what the approx. cost of this customised Silk was? I assume that it's north of 4.5k USD, but by how much? Thanks, Rik

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    1. This came in right around $5100.

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  3. This comment has been removed by the author.

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  4. Could this be purchased as a frameset as I already have a Rohloff I could use? Thank you.

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    1. Bike Friday does not sell their frame sets alone, but we can work with you to build your Speedhub into a complete bike. Please email us at info@cyclemonkey.com to discuss details.

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  5. I made a stop-motion video on how the Silk folds and unfolds: https://plus.google.com/105844089988748011433/posts/1P1RACK7jzc

    There is also a close-up photos of the Silk when it was unboxed:
    https://plus.google.com/105844089988748011433/posts/2J2gKvaZJuo

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  6. Can you please tell me how long the rohloff cables must be (1,80 or 2,50) I am converting my NWT to external and donk now which cables to buy
    Thank you very much

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    1. The standard length (1.8m) cables generally work, so unless you have an usually long frame or large handle bars, these should be the right length.

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  7. Neil do you always put the rohloff box down? looks very close to the ground,I need to decide how to put my
    Thanks

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    1. That is my preferred cable routing setup, and we use it on almost all bikes. I know with smaller wheels, the cable box ends up closer to the ground, but a) it still sits about the place as the disc brake rotor, and b) we've never had a complaint.

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