Indoors and out, my bike position changes a small amount each season.
My road bike tends to define my optimal position at the end of the summer. It includes millimeter adjustments made over the course of several thousand kms. Similarly, my indoor bike defines my optimal position at the end of the winter.
When I have settled on a new optimaI position, I like to transfer it to my other bikes, including: road, gravel, indoor and time-trial.
Transferring Bike Measurements
Assuming you have one bike with your optimal position, you need a method for transferring the riding position to multiple bikes.
Prerequisites and Notes:
Cranks - All bikes have same crank length. Watch for small differences in pedal platform height.
Saddles vary - They can have different lengths and widths. To create a standard measurement position on all saddles, I use the top of the saddle where it touches the pelvic bone. This is near but not exactly the widest point on most saddles. I put a mark on the saddle since this point is used in subsequent measurements.
Handlebars vary - Brake levers will often need to be moved to accommodate different reach and drop radius angles between handlebars. Keep this mind. A solution is provided below.
Here's the method I have used for decades.
1. Seat Height: Measure distance from the centre of the crank axle to top of the saddle at the pelvic bone position.
2. Saddle Setback: Use a vertical level or plumb-bob to measure the horizontal distance from the centre of the crank axle to the pelvic bone position.
3. Handlebar Reach: Measure the distance from the pelvic bone position to the back edge of handlebar tops.
4. Handlebar Drop:Use a horizontal level to measure the vertical distance from top of saddle (at the pelvic bone position) to the top of the handlebars.
5 - 8. On the target bike: Adjust the target bike to reproduce each of the 4 measurements from the reference bike. Be prepared to iterate when you discover you didn't measure everything correctly.
A Better Way
Setting up a new bike requires 8 steps. It can be tedious and error prone. To make bike fit transfers easier, I constructed TheFit Frame. It allows critical measurements to be transferred in one step.
The Fit Frame has adjustable arms that lock the Seat Height, Saddle Setback, Handlebar Reach and Handlebar Drop measurements.
Reproducing bike fit is as simple as moving The Fit Frame to another bike.
Movable bumpers mark the crank axle centre, pelvic bone position, handlebar height and reach along with other critical heights and distances. A pair of spirit levels keep the frame properly aligned on all axes.
This version also has extension arms to measure brake hood position on tricky bikes like my SB20 indoor bike.
Made withfrom a 3D Printer
The Fit Frame is not quite 3D printed. It's made from the aluminum extrusions, gusset plates and hex fasteners used to construct 3D printers 😂.
Plus a table saw to cut everything along with a some patience to figure out how to assemble this kind of frame.
=========== UPDATE 🎉 ===========
Today, I received a new saddle from AliExpress. It is flatter, thinner (with wider nose) and longer than the Stages saddle. I was able to mount and replicate my position versus the original saddle in a few minutes using the The Fit Frame. Adjustments included more setback and slightly lower seat height.
My back and knees said thanks.
Saddle Details: There are two models.
Nylon frame and steel rails 260g I bought this one for indoor riding.
Carbon frame and rails160g (recommended) 25% higher cost. Appears to be more robust. I bought this one for outdoors.
STAGES SB20 DRIVE BELT ADJUSTMENT Stages includes belt adjustment tips in their support note on fixing SB20 noises: Flywheel Making Noise . Several people have mentioned these instructions are incomplete. I’ll try to help . I wish this process was easier. Good news: With practice, you can complete all adjustments in less than 30 minutes. TWO GOALS Adjusting the drive belt accomplishes two things: Align the belt to ride as much as possible in the centre of the drive cogs. This reduces friction and positions the front axle perpendicular to the drive belt. Don’t be too worried about this step. The SB20 manufacturing tolerances aren’t perfect. Getting the front drive wheel roughly aligned and generally perpendicular is about all we can expect to achieve. Get belt tension right. Optimal tension means quieter running and no slipping during hard efforts. For most of us, this is a trial-and-error process.You want tight but not too tight. For me, this is measured as a 1 cm deflection when p
The Stages SB20 indoor smart bike was released in 2020. Let's take a look at the electronics that enable it on platforms like Zwift.com and TrainerDay.com. An external power supply routes power to different bike components through a series of printed circuit boards (PCBs). The bike also includes two battery powered crank-based power meters. Here's an overview the basic functions: USB Board - Wedged vertically under the phone tray. It powers 3 USB ports. Upper Board - Fastened horizontally under the phone support rail. This System On a Chip (SoC) handles wireless communication and controls the bike itself. Switch Board - This wire distribution board sits inside the aluminum handlebar stem. It routes connections for the brake level controls and under handlebar tape "blip" shifter buttons. Lower Board - This mainly analog circuit board is attached to the flywheel / electronic brake unit. It controls bike resistance and sends power to other PCBs. Power Meters - A
10 of 10 - Leaning one way and another Rocker plates make indoor riding more realistic. I'm not entirely convinced. Indoor bikes struggle to recreate outdoor resistance, road conditions, pedalling dynamics and acceleration. I'm not sure that side-to-side movement helps with realism. My personal take is more conservative. Two years of rocker plate riding has improved my overall comfort and helped with out-of-saddle sprints. My Journey I began experimenting with different rocker plate designs in 2021, starting with the following requirements: ✓ Progressive side-to-side movement that offers stronger resistance as you move from the upright or vertical position. ✓ Forward-and-back movement. Many riders claim this is a critical element in real-world riding simulations. ✓ Small footprint. Commercial products are often quite large to accommodate a wide range of bikes. A custom design for my particular bike should be smaller. ✓ It should remain easy to get on and off the bike.
My SB20 smart bike comes with an app that shows power, distance, cadence, L:R balance and current virtual gear. You can also use a bike computer like a Garmin 540/840/1040 to show similar data. When you use either at the same time as Zwift, you see different numbers. Who is correct? Answer: They are ALL CORRECT and ALL WRONG! How can that be? Let's find out. Before getting started, it's a good idea to agree on basic parameters. Note: In this discussion, I use the term Indoor bike for smart bikes and smart trainers along with their related apps. RESISTANCE AND POWER 1. RESISTANCE - An indoor bike creates resistance that makes it harder or easier to pedal. 2. POWER - The harder you push against the indoor bike's resistance (measured in newton metres) multiplied by how fast you pedal (RPM) defines the POWER you are producing (specified in watts per second or just watts). POWER is a measured number and is EXACTLY the same if you are riding with Zwift, using your
Torque Measurement I previously documented how to compare SB20 power meters with a set of calibrated pedals. It gives you a good indication of how your power meters compare in actual riding scenarios. This test statically measures torque with a pair of fixed weights. It tells you if your power meters meet factory specifications . This test does not provide the full calibration that you can perform with Garmin or Favero pedals. You can't change offset or slope parameters to get the Stages PM measure correctly in the future. Basic Testing Procedure The basic method involves two ( big ) steps: 1. P osition the cranks horizontally to get raw measurements produced by hanging 25 lb weights from each crank. 2. Use a spreadsheet to process raw measurements and get an average reading for both cranks. Compare these readings against expected values (t he list of expected values is shown later in this post ). The test setup looks like this: With equal weights on each side, cranks can
Today's question: How does battery level affect SB20 power meter measurement? Let's do a deep dive and find out! Replaceable Batteries The Stages SB20 power meters have replaceable batteries. An advantage: No degradation of built-in batteries as the power meters age. A disadvantage: No ability to top up batteries to 100% whenever you wish. Battery Life CR2032 button cell batteries are used in the SB20 power meters. Stages says they should last 150-200 hours . Let's verify this claim with bench tests and torque measurements. Estimating Remaining Capacity The StagesPower app, and others like BT Inspector, report battery capacity. They use the Bluetooth Low Energy (BLE) wireless protocol to ask each power meter for a battery life estimate. 🔬It doesn't matter which app you use. All apps report the estimate returned by the power meters. Why Battery Estimates are so Bad Many people complain that battery life estimates from the power meters show 100% most of time. The
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