The Monkey Lab: Fixie

Showing posts with label Fixie. Show all posts

13 November 2014

Soma Rush Fixed Gear With Belt Drive

When a local customer contacted us about building a belt drive-equipped fixed gear for him, we were excited to execute his vision. He wanted a bike that would be simple, lightweight, and durable for commuting around town quickly. He gave us a few general guidelines for the build but asked us to make our own recommendations for parts that would fulfill his requirements. His primary requests were that the frame be chrome colored and that he could use a belt drive system. He planned to use the bike to zip around Oakland and commute across town to work - primarily short, fast rides without much climbing.

Schlumpf Mountain Drive-Equipped Cinelli Gazzetta

Cinelli Gazzetta in the form of a classically styled two-speed fixed gear

We built this beautiful Cinelli for the son of a good friend of ours who wanted a fixed gear commuter bike with classic styling. We started with the bright red Gazzetta steel track frameset and added mostly polished silver parts and a two-speed Schlumpf Innovations Mountain Drive. The Mountain Drive unit gives the bike a second gear for climbing while maintaining a clean looking drivetrain and the fixed gear format.

Columbus tubing and small details on the seat binder lug

Schlumpf-Equipped Leader 725 Two Speed Fixie

We built this black and white Leader 725 recently for a customer in Toronto, ON Canada. He was looking for a fixed gear bike with clean lines to commute on but wanted to have more than one gear to deal with hills. A Schlumpf Speed Drive was a natural fit as it offers two gear choices without any cables or hand shifter. The customer had been interested in getting a frame from Leader Bike and decided that the 725 model fit his budget and offered the aesthetic he was looking for.

For the wheels, we went with White Industries track hubs laced into Velocity Dyad rims using Sapim Race spokes and brass nipples. Dyads are one of our favorite rims; we've used them for many applications - road, touring, fixie, commuting, and mountain. At 24mm wide and 22mm high, it has the width of a typical touring or cross country mtb rim. The sidewalls are thicker than a standard road rim, so it can handle more abuse. When used in more of a road/fixie application, the extra wide spreads the tire out more to provide increased comfort and traction.

The Leader 725 model is a stout aluminum track frame built for the rigors of urban fixed gear riding. It has short chainstays for tight handling with stainless steel plates to protect the dropouts from the axle nuts. An oversized headtube with internal headset stiffen up the front end. The minimal decals on this frame were part of the appeal for the customer as they don't loudly scream an advertisement at you.

Build details

Frame: Leader 725 Aluminum
Fork: I-806A V2 Aluminum Track
Headset: Cane Creek 40
Stem: Truvativ Hussefelt
Handlebar: Cinelli Pepper
Grips: Oury
Saddle: Brooks B17 Special
Front Hub: White Industries Track
Rear Hub: White Industries Track
Spokes: Sapim Race
Nipples: Sapim Brass
Rims: Velocity Dyad
Tires: Continental Grand Prix 4-Season
Cranks: Schlumpf
Bottom Bracket/Gear Box: Schlumpf Speed Drive
Chainring: Surly Stainless
Chain: Wipperman 7R8
Rear Sprocket: White Industries splined track
Pedals: Fyxation Gates

15 January 2012

Schlumpf-Equipped Brooklyn Machine Works Gansta Fixie

When Schlumpf redesigned their clutch plates to make them compatible with fixed gear bikes, Neil wanted a unique frame to test/showcase a Speed Drive unit. The Brooklyn Machine Works Gansta Track frame fit the bill with its pierced top tube, box-section fork crown, and airfoil fork legs, seat stays, and chain stays. Only problem - the frame had no provision for a brake. After a couple calls to BMW and some brainstorming on their part, they agreed to fabricate a disc brake mount for the fork. Now we were in business.

The frame got a sparkly clear coat over a gloss black base, so we wanted to use shiny silver wheel parts to compliment this finish. We went with polished Phil Wood hubs - 32 hole bolt on disc front and 36 hole fixed/fixed bolt on high flange track rear- laced into bright silver Velocity Deep V's using Sapim Race spokes and brass nipples. A 2 leading/2trailing lacing pattern was used on the front and a 3 leading/3 trailing lacing pattern was used on the rear. Spoke color (black/silver) was alternated between each bundle of spokes (bundles of 4 on front wheel, bundles of 6 on the rear) to give the wheels contrast while spinning.

The heart of the project was the hidden gear box. The Schlumpf systems give you two gear ratios using a single chain ring that is connected to a two-speed internal gear system encased in the bottom bracket. The Speed Drive model offers a ratio change just slightly larger than a standard road front derailleur and double crankset (65% change). Since the chain remains on a single ring, a single speed or fixed gear bike with a tensioned chain can become a 2-speed. The updated clutch plate design allows the gear box to transmit torque in two directions, making it compatible with fixed gear bikes.

The gear ratio is changed by intentionally knocking buttons on each side of the bottom bracket axle with your heels (silver button in the center of the crank set). In one mode, the Speed Drive acts like a standard bottom bracket and crank set: the chainring and crank arms spin at the same rate. In the other mode, the Speed Drive gearbox over-drives the chainring: the chainring now spins faster than the crank arms, providing a larger effective chainring size.