03 January 2014

Nirve Switchblade Chopper Rohloff Conversion


This Nirve “Switchblade” chopper, styled after a classic motorcycle, is one of the more unusual bikes we've had in for a Rohloff conversion. We have experience installing Rohloff hubs on almost every type of bike, but this was a new one for us. The goal was to give this extremely relaxed, comfortable bike the low gearing to pedal up and over more hills.

The owner of this bike lives in San Francisco and uses it to cruise around the waterfront and flatlands, but he also wanted to be able to pedal up some of the city’s many steep hills. The bike had come with a three speed coaster brake hub, but he wasn't satisfied with its limited gear range. He also has a trailer that he uses often to carry groceries and gear, so he wanted a durable drivetrain that would be strong enough to haul plenty of weight.



Our customer bought this bike in part because he likes the classic styling but more importantly because he likes how comfortable and relaxed it is to pedal. The chopper puts you in a very leaned-back seating position, with the cranks and pedals far in front of you and the handlebars very high in the air. The one limiting factor, however, is getting up hills in this seating position.



The Rohloff SPEEDHUB has the largest gear range of any internally geared hub on the market and is an ideal choice for this style of bike. Since the geometry of the bike doesn't allow you to stand up and crank hard on the pedals, climbing hills is easiest with a low gear and steady pace. The SPEEDHUB gives you a 526 percent change in gearing across 14 gears, ensuring a very low and very high gear to get over all kinds of terrain.

For the wheel build, we laced a silver SPEEDHUB up to a 24 by 3 inch aluminum rim, designed to fit larger volume tires for a comfortable ride. For the front wheel, we used a larger 26 by 2.5 inch rim on a silver Schmidt SON 28 dynamo hub. We hooked up the generator hub to a Busch & Muller Lumotec Classic front light, giving him plenty of battery-free lighting for night time cruising.



We had to make a few adaptations to the stock setup in order to make the rear wheel compatible with the chopper frame. Because the frame was based around the use of a coaster brake hub it did not have any brake mounts, either disc or rim. Rohloff does not offer a coaster or drum brake hub option, so we needed to install brake mounts of some kind. Our customer found and brought us a special disc brake mount adapter that is installed around the hub’s axle and is secured to the dropout.

Once the brake issue was settled, we used the Rohloff long torque arm to anchor the hub’s torque input to the frame. The cable routing was a bit unusual due to the orientation of the brake mount and the shape of the frame. We had loop the brake and shift cables backwards around the dropouts instead of running them along the chainstays.



A variety of leather and chrome components give this bike a classic chopper appearance. A leather Brooks saddle, grips, and front fender mudflap match the leather handlebar bag. A chrome handlebar and polished stem match the silver wheels we built. The spiked silver Tioga Spider pedals finish off the bike's look.



The bike now offers the gear range needed to pedal around San Francisco while still maintaining the unique chopper style our customer was after. When he came to pick up the bike, he was very pleased with the new-found range the SPEEDHUB gave him. He said he was excited to ride around the city on a much more regular basis. If you want to do a Rohloff conversion on your own bike, contact us to discuss the details!

Build Details:

• Frame: Nirve Switchblade
• Fork: Nirve 
• Headset: Chromed steel
• Stem: Polished aluminum
• Handlebar: Chromed steel chopper bars
• Shifter: Rohloff
• Grips: Brooks Plump Leather
• Seatpost: Chromed steel
• Saddle: Brooks B66
• Seat Clamp: Nirve
• Front Hub: Schmidt SON 28
• Rear hub: Rohloff SPEEDHUB 500/14
• Spokes: Sapim Race
• Nipples: Sapim Brass
• Rims: Wide chopper
• Tires: Innova 24x3.0 rear, Innova 26x2.5 front
• Cranks: Race Face Turbine
• Pedals: Tioga Spider
• Bottom Bracket: Race Face Turbine
• Chain ring: Surly Stainless Steel
• Chain: Wipperman Connex 7R8
• Brakes & Levers: Tektro 319A BMX brakes, Avid BB7 MTN calipers
• Rotors: Magura Storm
• Extra: Busch & Muller Lumotec Classic front light, Busch & Muller 4-D Lite Plus tail light, chain guard, fenders, handlebar bag

4 comments:

  1. email me @ pauleduarddeguzmanatgmail.com, if your interested in selling it.

    ReplyDelete
  2. nice job!
    Would you please tell me the name/type of the handle bar.
    How did you get the big rear wheel into the frame, did you spread the frame?
    Have you need an offset sprocket?

    ReplyDelete