Sheldon Brown's Bicycle Frame and Cassette Spacing Crib Sheet

As of 2018, fatbikes and disc brakes have led to a several new standards. The problem of disc brakes' pulling the hub out of the front dropouts (see James Annan's article) has been addressed with thru axles, which insert into a fork with a hole rather than a slot at the end of each blade. Also see our article on thru axles, and our article about disc brakes for information on disc-brake issues.

Front
70 mm	Birdy, Breezer Itzy front hub.
74 mm	Brompton front hub, 8 mm axle; Schimidt SON XS Bro generator hub.
Bike Friday tikit, Dahon Speed, Moulton front hub, 9 mm axle; Schmidt SON XS DaTi generator hub
79 mm	Dahon Vitesse front hub (report from reader, unconfirmed).
91 mm	Low-end front hubs; Nottinghum Raleighs.
96 mm	Older front hubs, especially French.
100 mm	Modern front hubs with 12 and some with 15mm thru axle
110 mm	"Boost" front hubs with 12, 15, or 20 mm thru axles.
120 mm	Some front "Boost"
135 mm	Front fatbike with quick release. Some are offset, and some front and rear wheels are interchangeable.
142 mm	Front fatbike with rigid thru-axle fork,15mm axle
150 mm	Some fatbike front hubs with 15mm thru axle
Rear
110 mm	Rear older track, coaster brake and other single-speed hubs.
114 mm	Rear 3-4-speed, many internal-gear hubs. This is US, U.K. Same as 4 1/2 inches.
120 mm	Rear 5-speed, Ultra 6, newer track hubs.
126 mm	Rear 6- and 7-speed (road).
130 mm	Rear 7-speed (MTB) and 8- 9-10-11-speed (road) except disc brake
135 mm	Rear 7- 8- 9-10-11-speed (MTB); rear with disc brake (road). Some MTB with 12mm thru axle
135 mm offset	Original Surly fatbike, offset 17.5 mm to right
140 mm	Rear tandem.
142 mm	Rear with 12mm QR, 12mm or 15mm thru axle
145 mm	Rear tandem (newer models.)
148 mm	Rear "Boost", MTB with 12mm thru axle
150 mm	Retro-Choppers, some Downhill and Freeride models.
157 mm	SRAM rear DH
160 mm	Rear tandem (new Santana proposed standard.)
170 mm	Rear symmetric fatbike with quick release for 4" tire
177 mm	Rear symmetric fatbike with thru axle for 4" tire, 12mm axle
190 mm	Rear symmetric fatbike with quick release for 5" tire, 12mm axle with QR
197 mm	Rear symmetric fatbike with thru axle for 5" tire, 12mm thru axle

Front

70 mm

Birdy, Breezer Itzy front hub.

74 mm

Brompton front hub, 8 mm axle; Schimidt SON XS Bro generator hub.

Bike Friday tikit, Dahon Speed, Moulton front hub, 9 mm axle; Schmidt SON XS DaTi generator hub

79 mm

Dahon Vitesse front hub (report from reader, unconfirmed).

91 mm

Low-end front hubs; Nottinghum Raleighs.

96 mm

Older front hubs, especially French.

100 mm

Modern front hubs with 12 and some with 15mm thru axle

110 mm

"Boost" front hubs with 12, 15, or 20 mm thru axles.

120 mm

Some front "Boost"

135 mm

Front fatbike with quick release. Some are offset, and some front and rear wheels are interchangeable.

142 mm

Front fatbike with rigid thru-axle fork,15mm axle

150 mm

Some fatbike front hubs with 15mm thru axle

Rear

110 mm

Rear older track, coaster brake and other single-speed hubs.

114 mm

Rear 3-4-speed, many internal-gear hubs. This is US, U.K. Same as 4 1/2 inches.

120 mm

Rear 5-speed, Ultra 6, newer track hubs.

126 mm

Rear 6- and 7-speed (road).

130 mm

Rear 7-speed (MTB) and 8- 9-10-11-speed (road) except disc brake

135 mm

Rear 7- 8- 9-10-11-speed (MTB); rear with disc brake (road). Some MTB with 12mm thru axle

135 mm
offset

Original Surly fatbike, offset 17.5 mm to right

140 mm

Rear tandem.

142 mm

Rear with 12mm QR, 12mm or 15mm thru axle

145 mm

Rear tandem (newer models.)

148 mm

Rear "Boost", MTB with 12mm thru axle

150 mm

Retro-Choppers, some Downhill and Freeride models.

157 mm

SRAM rear DH

160 mm

Rear tandem (new Santana proposed standard.)

170 mm

Rear symmetric fatbike with quick release for 4" tire

177 mm

Rear symmetric fatbike with thru axle for 4" tire, 12mm axle

190 mm

Rear symmetric fatbike with quick release for 5" tire, 12mm axle with QR

197 mm

Rear symmetric fatbike with thru axle for 5" tire, 12mm thru axle

Overall axle length for quick-release hubs is commonly 11 mm longer than the overlocknut distance listed, 5.5 mm on each side. Most hubs with nutted axles can easily be modified for larger spacing by adding washers, within limits. For overlocknut distance of specific makes and models of internal-gear and singlespeed hubs, see the articles on chainline.

Cassette /Freewheel Spacing

Sprocket spacing given is for inner sprockets. Spacing of outer sprockets may be slightly greater to prevent the chain from rubbing against the next larger sprocket. Overall width of freewheels and cassettes may therefore slightly exceed the dimensions given. Some SunTour freewheels used oddly mixed spacings -- see linked photos.

Brand and model	Center-to-center Spacing	Sprocket Thickness	Spacer Thickness	Total Width
5-speed
"Regular" 5-speed	5.5 mm	2.0 mm	3.5 mm	24.0 mm
G. Caimi/Everest/Simplex 5-speed	5.35 mm	1.85 mm	3.5 mm	23.2 mm
6-speed
"Regular" 6-speed	5.5 mm	2.0 mm	3.5 mm	29.5 mm
G. Caimi/Everest/Simplex 6-speed	5.35 mm	1.85 mm	3.5 mm	28.6 mm
Sun Tour "Ultra" Freewheel 6-speed	5.0 mm	1.85 mm	3.15 mm	26.9 mm
Sun Tour Accushift XCD-6 6-speed	5.5 mm	2.0 mm	3.5 mm	29.5 mm
7-speed
Shimano HG 7-speed	5.0 mm	1.85 mm	3.15 mm	31.9 mm
Shimano IG 7-speed	5.0 mm	2.35 mm	2.65 mm	32.4 mm
Sachs 7-speed	5.0 mm	1.8 mm	3.2 mm	31.8 mm
SRAM Freewheel 7-speed	5.0 mm	1.8 mm	3.2 mm	32.8 mm
Sun Tour "Ultra" Freewheel 7-speed	5.0 mm	1.85 mm	3.15 mm	32.4 mm
Sun Tour MicroDrive 7-speed	4.8/5.0 mm	2.0 mm	3 x 2.8 mm(L) 3 x 3.0 mm(H)	31.5 mm
8-speed
Campagnolo 8-speed	5.0 mm	1.9 mm	3.1 mm	36.9 mm
Mavic 8-spd w/rounded dogs	5.2 mm	2.0 mm	3.2 mm	37.0 mm
Shimano 8-speed	4.8 mm	1.8 mm	3.0 mm	35.4 mm
Sachs 1997 8-speed	5.0 mm	1.8 mm	3.2 mm	36.8 mm
Sachs 1998+ 8-speed	4.8 mm	1.8 mm	3.0 mm	35.4 mm
SRAM Cassette 8-speed	4.8 mm	1.8 mm	3.0 mm	35.4 mm
SRAM Freewheel 8-speed	5.0 mm	1.8 mm	3.2 mm	36.8 mm
Sun Tour MicroDrive 8-speed	4.8/5.0 mm	2.0 mm	3 x 2.8 mm(L) 4 x 3.0 mm(H)	36.5 mm
9-speed
Campagnolo 9-speed	4.55 mm	1.75 mm	2.8 mm	38.2 mm
Shimano 9-speed	4.34 mm	1.78 mm	2.56 mm	36.5 mm
SRAM 9-speed	4.34 mm	1.8 mm	2.54 mm	36.5 mm
10-speed
Campagnolo 10-speed	Variable (note)	1.7 mm	Variable (note)	38.8 mm
Shimano 10-speed	3.95 mm	1.6 mm	2.35 mm	37.2 mm (note)
11-speed
Campagnolo 11-speed	Variable (note)	1.6 mm	Variable (note)	40.1 mm (note)

Brand and model

Center-to-center
Spacing

Sprocket Thickness

Spacer Thickness

Total Width

5-speed

"Regular"
5-speed

5.5 mm

2.0 mm

3.5 mm

24.0 mm

G. Caimi/Everest/Simplex
5-speed

5.35 mm

1.85 mm

3.5 mm

23.2 mm

6-speed

"Regular"
6-speed

5.5 mm

2.0 mm

3.5 mm

29.5 mm

G. Caimi/Everest/Simplex
6-speed

5.35 mm

1.85 mm

3.5 mm

28.6 mm

Sun Tour "Ultra"
Freewheel 6-speed

5.0 mm

1.85 mm

3.15 mm

26.9 mm

Sun Tour Accushift
XCD-6 6-speed

5.5 mm

2.0 mm

3.5 mm

29.5 mm

7-speed

Shimano HG
7-speed

5.0 mm

1.85 mm

3.15 mm

31.9 mm

Shimano IG
7-speed

5.0 mm

2.35 mm

2.65 mm

32.4 mm

Sachs
7-speed

5.0 mm

1.8 mm

3.2 mm

31.8 mm

SRAM Freewheel
7-speed

5.0 mm

1.8 mm

3.2 mm

32.8 mm

Sun Tour "Ultra"
Freewheel 7-speed

5.0 mm

1.85 mm

3.15 mm

32.4 mm

Sun Tour
MicroDrive 7-speed

4.8/5.0 mm

2.0 mm

3 x 2.8 mm(L)
3 x 3.0 mm(H)

31.5 mm

8-speed

Campagnolo
8-speed

5.0 mm

1.9 mm

3.1 mm

36.9 mm

Mavic
8-spd w/rounded dogs

5.2 mm

2.0 mm

3.2 mm

37.0 mm

Shimano
8-speed

4.8 mm

1.8 mm

3.0 mm

35.4 mm

Sachs
1997 8-speed

5.0 mm

1.8 mm

3.2 mm

36.8 mm

Sachs 1998+
8-speed

4.8 mm

1.8 mm

3.0 mm

35.4 mm

SRAM Cassette
8-speed

4.8 mm

1.8 mm

3.0 mm

35.4 mm

SRAM Freewheel
8-speed

5.0 mm

1.8 mm

3.2 mm

36.8 mm

Sun Tour
MicroDrive 8-speed

4.8/5.0 mm

2.0 mm

3 x 2.8 mm(L)
4 x 3.0 mm(H)

36.5 mm

9-speed

Campagnolo
9-speed

4.55 mm

1.75 mm

2.8 mm

38.2 mm

Shimano
9-speed

4.34 mm

1.78 mm

2.56 mm

36.5 mm

SRAM
9-speed

4.34 mm

1.8 mm

2.54 mm

36.5 mm

10-speed

Campagnolo
10-speed

Variable (note)

1.7 mm

Variable (note)

38.8 mm

Shimano
10-speed

3.95 mm

1.6 mm

2.35 mm

37.2 mm
(note)

11-speed

Campagnolo
11-speed

Variable (note)

1.6 mm

Variable (note)

40.1 mm
(note)

Total width

The total width given is that of the sprocket cluster --which may also be slightly wider due to wider spacign of the smaller sprockets.. A freewheel with splined sprockets has a flange behind the innermsot sprocket. The inner body of the freewheel may not be recessed so as to compensate completely for this flange depth, and so the total width the of the freewheel may be greater, affecting chainline and clearance at the right rear dropout. Sun Tour freewheels typically have a 2 mm flange and a 1 mm recess.

Overhang

The innermost sprocket of Shimano 10-speed and Campagnolo 11-speed cassettes is inboard of the flange of the freehub body to move the sprockets to the left and make more room between the outermost sprocket and the dropout. The rear derailer may interfere with the spokes, especially if the innermost sprocket is relatively small or the wheel has an unusual spoke pattern.

Variable spacing

Sprocket spacing varies across Campagnolo 10- and 11-speed cassettes to improve shifting in the midrange. 11-speed spacing also varies over the top 3 sprockets according to the actual ratios for better shifting with the most recent 11-speed rear derailleur. Thanks to Graeme at Velotech Cycling Ltd. (UK) for this information.