Yourbike.cc | Bike parts know-how

Bikeparts know-how

If you plan to mix parts from different groupsets, this page provides valuable information. If you aren’t mixing groupsets, you generally won’t have compatibility issues, so you can skip this page unless you’re curious. With groupset we mean the drivetrain parts included in a product group like i.e. SHIMANO’s “105”, it includes parts like shifters, derailleurs, crankset, bottom bracket, chain and cassette.

Let’s Get Started

When choosing matching components such as a crankset, derailleurs, or a complete groupset, it’s important to understand that not all parts are interchangeable unless they come from the same groupset or groupset family (105, Ultegra, SRAM Red or Force). To achieve optimal shifting performance, it helps to know the following key terms:

Chainline
Chainring gap
Chainring jump
Q-factor
Crank length
Bottom brackets
Cable pull ratio

The picture illustrates terms 1–5, which we’ll explain together with 6 and 7 in more detail. For reference, we’ve also included a table listing chainline measurements and Q-factors of specific groupsets here below.

1. Chainline

Chainline refers to the distance between the centerline of the bicycle frame and the line along which the chain runs.

For a 1x setup, the chainline is the distance from the center of the frame to the single front chainring.
For a 2x setup, it’s measured to the midpoint between the small and large chainrings. The picture above illustrates the measurements.

Importance: Chainline matters for the shifting performance and the wear and tear of the chain, chainblades and cassette. Different front and rear derailleurs are made for specific chainlines. When using a crankset different from the groupset, aim for ~1 mm of the recommended value for optimal shifting.

2. Chainring Gap

The distance between the inner and outer chainrings on a crankset. Proper spacing ensures smooth shifting. Narrow gaps are generally better for shifting, but must accommodate the chain without rubbing. Typical road bikes: ~5 mm; older or triple cranksets: up to 7.5 mm.

Importance: Only relevant when mixing cranksets and a front derailleur from a different groupset because front derailleurs are optimized for a specific chainring gap.

3. Chainring Jump

The difference in tooth count between the large and small chainrings. Smaller jumps = smoother gear changes and better cadence control.

Importance: front derailleurs are designed for a certain jump. Changing cranksets may affect shifting performance.

4. Q-Factor

The distance between the outside of one crank arm to the outside of the other: essentially how far apart your feet are while pedaling.

Importance: for indoor setups, matching your outdoor bike’s Q-factor can be preferred, but ideally the Q-factor matches the aspects of your own body like hip width and keen stance. Wider Q-factors can improve comfort and stability, especially on mountain or indoor bikes. Road bikes generally have narrower Q-factors to reduce pedal strikes during cornering whilst keeping on pedaling in the corner.

5. Crank Length

Crank Length is the distance from the center of the bottom bracket (where the cranks rotate) to the center of the pedal axle. It’s usually measured in millimeters (mm) and typically ranges between 165 mm and 175 mm for adult bikes. Common road bike crank length is 172.5 mm.

Crank length affects:

Pedal stroke mechanics
Knee and hip angles
Cadence
Leverage and torque

Longer cranks give more leverage, which can be useful for low-cadence climbing.
Shorter cranks allow higher cadence, reduced knee/hip compression, and easier positioning (especially in aero or time trial setups). Shorter cranks are seen more often on MTB

Recommendations:

If your current crank length feels comfortable and causes no discomfort during or after cycling, it’s best to stick with it. Research shows no significant difference in maximal power across common crank lengths (165–175 mm), even with variations of up to 20 mm.

Key Studies:

Martin & Spirduso (2001)
Tested crank lengths were 120, 145, 170, 195, and 220 mm. Result: Power output remained nearly unchanged across that range. Efficiency was optimal between 145–170 mm.
Ferrer Roca et al. (2014)
±5 mm variations had no significant effect on gross efficiency, heart rate, oxygen uptake, or RER. Longer cranks increased torque fluctuations and slightly increased hip/knee range of motion (~1–3°).
Bini et al. (2017)
Crank length has minor effects on oxygen uptake, power, or torque, unless you go outside the typical range.

6. Bottom brackets

A bottom bracket is the bearing system inside the bike frame that lets the crankset spin smoothly. Bottom brackets come in different shell types (like BSA threaded, Italian, Press-Fit, T47) which describe how the bottom bracket fits into the frame.

The spindle interface is how the crank arms attach to the bottom bracket spindle. Common types are:

Square Taper (JIS) – classic, simple, reliable.
ISIS / Octalink – splined spindles for more stiffness.
External systems (e.g., Hollowtech II, GXP, DUB) – larger spindles with outboard bearings for strength and lower weight.

In short: the shell type fits the frame, the spindle interface fits the crank.

Importance: Bottom brackets and spindle interfaces must match your frame and crankset. If they’re not compatible, the parts simply won’t fit together, or they’ll wear out quickly.

7. Cable Pull Ratio

Cable pull refers to the amount of cable that a shifter moves (pulls or releases) each time you click it. It's crucial because it needs to match the derailleur’s actuation ratio, which is how much the derailleur moves sideways in response to the cable movement. There are two factors involved:

Shifter Cable Pull: How much cable the shifter moves per click.

Derailleur Actuation Ratio: How far the derailleur moves per mm of cable pulled.

Importance: Shifters and derailleurs from different brands or groupsets are often incompatible. Road vs. MTB groupsets may also differ in ratios.

Here is a summary of compatibility tor roadbike groupsets:

Campagnolo uses much lower pull per shift (~1.4–1.7 mm) and a unique derailleur ratio, making it highly incompatible with SRAM or Shimano.
LTWOO offers versions that replicate either Shimano or SRAM ratios — be sure to confirm which one before pairing.
microSHIFT generally follows Shimano’s standard pull ratios, making it well-suited for mixing with Shimano road/GRX systems. However; there are examptions so it's wise to look in to it.
SENSAH divides into two product lines: SRX Pro shifters follow SRAM (~3.1 mm pull, ~1.1 actuation); Team Pro shifters follow Shimano (~2.51 mm pull, ~1.4 actuation).
Shimano road (11-speed/Tiagra/105/Ultegra/Dura-Ace/GRX) uses ~2.7 mm pull and ~1.4 derailleur ratio.
SRAM Exact Actuation (road 9/10/11) uses ~3.1 mm pull and ~1.1 derailleur ratio.

For MTB groupsets its again another story, so be sure to look in to it thoroughly before mixing and matching.

TABLE: Roadbike crankset chainline and Q-factors

Groupset

Campagnolo Record, Chorus - 10

Campagnolo Chorus, Record, Super Record - 11

Campagnolo Chorus, Record, Super Record - 12

L‑TWOO RX Road

MicroSHIFT Centos 10

MicroSHIFT Centos 11

microSHIFT SWORD Black

microSHIFT SWORD

Sensah Team Pro

Sensah Empire / SRX Pro / Empire Pro

SHIMANO Tiagra FC-4700

SHIMANO 105 FC-5700

SHIMANO 105 FC‑5800

SHIMANO 105 FC‑R7000

SHIMANO 105 FC‑R7100

SHIMANO CUES Ultegra FC-6700

SHIMANO CUES Ultegra FC‑6800

SHIMANO CUES Ultegra FC‑R8000

SHIMANO CUES Ultegra FC‑R8100

SHIMANO Dura‑Ace FC‑79000

SHIMANO Dura‑Ace FC‑R9000

SHIMANO Dura‑Ace FC‑R9100

SHIMANO Dura‑Ace FC‑R9200

SHIMANO CUES U4000-1 (30T or 32T)

SHIMANO CUES U4000-1 (40T or 42T)

SHIMANO CUES U6000-1 (30T or 32T)

SHIMANO CUES U6000-1 (40T or 42T)

SHIMANO CUES U8000-1 (40T or 42T)

SHIMANO CUES U4000-2 (36-22T, 40-26T)

SHIMANO CUES U6000-2 (36-22T, 46-30T)

SHIMANO CUES U8000-2 (46-32T)

SRAM Apex 1

SRAM RED, Force, Rival - 22

SRAM RED eTap - 22

SRAM Force 1, Rival 1

SRAM RED eTap AXS - 12 / 24

SRAM Force eTap AXS - 12 / 24

SRAM Force AXS Wide - 12 / 24

SRAM Rival AXS - 12 / 24

SRAM Rival AXS WIDE - 12 / 24

SRAM Apex AXS (XPLR) WIDE - 12 / 24

SRAM RED AXS 2025 - 24

ZWIFT Ride + Cog v2 setup (42x14T)

Configuration

2x10

2x11

2x12

2x10

2x11

1x9

2x9

1x10

2x10

2x11

1x11 / 2x11 / 2x12

2x10

2x11

2x12

2x10

2x11

2x12

2x10

2x11

2x12

1x9 / 1x10 / 1x11

2x9 / 2x10 / 2x11

2x11

1x11

2x11

1x11

1x12 / 2x12

2x12

1x1

Chainline (mm)

43.5

~43.5 mm

43.5

50.0

47.0

50.0

47.0

43.5

~43.5 mm

43.5

44.5

43.5

44.5

43.5

44.5

52.0

50.0

52.0

50.0

48.8

45.5

45.0

47.5

45.0

47.5

45.0

37 to 43

Q‑Factor (mm)

145.5

n/a

154.0

146.0

n/a

150.0

145.0

146.0

148.0

147.0

148.0

146.0

148.0

147.0

146.0

148.0

178.0

180.0

178.0

180.0

149.0

145.5

150.0

145.5

150.0

145.5

150.0