Chainline on fixed-gear and singlespeed bikes

Today I entertained myself by measuring a bunch of hubs, sprockets and singlespeed freewheels.

I discovered that there is considerably less standardization in terms of chainline than I had
supposed, and that if you want to get it right, a bit of extra care may be called for.

I've put my data into the Chainline entry of my Bicycle Glossary, though this may at a later date
grow into a stand-alone article on single speed chainline.

The main Chainline entry is at:

http://sheldonbrown.com/gloss_ca-m.html#chainline

The tables of sprockets, freewheels and hubs are at:

http://sheldonbrown.com/gloss_ca-m.html#chainline1

I welcome additional data points from readers.

Sheldon "Numbers" Brown +----------------------------------------------------------------+
| Anyone who cannot cope with mathematics is not fully human. | At best he is a tolerable
| subhuman who has learned to wear | shoes, bathe, and not make messes in the house. | --Robert
| A. Heinlein |
+----------------------------------------------------------------+ Harris Cyclery, West Newton,
Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts
shipped Worldwide http://captainbike.com http://sheldonbrown.com

 

In a Valentine gift to us all, Sheldon Brown <[email protected]> wrote:

>I discovered that there is considerably less standardization in terms of chainline than I had
>supposed, and that if you want to get it right, a bit of extra care may be called for.
>
>I've put my data into the Chainline entry of my Bicycle Glossary, though this may at a later date
>grow into a stand-alone article on single speed chainline.
>
>The main Chainline entry is at:
>
> http://sheldonbrown.com/gloss_ca-m.html#chainline
>
>The tables of sprockets, freewheels and hubs are at:
>
> http://sheldonbrown.com/gloss_ca-m.html#chainline1
>
>I welcome additional data points from readers.

Thanks for assembling this important resource. Here follows some measurements I took of some hubs
not mentioned in your tables:

Campagnolo Pista (2002 type, small flange) : Nominal OLD - 120 Measured OLD - 120.6 Centerline to
sprocket shoulder - 36

Campagnolo Pista (Record C type, large flange) : Nominal OLD - 120 Measured OLD - 120.1 Centerline
to sprocket shoulder - 35.9

Shimano 7710 (small flange) : Nominal OLD - 120 Measured OLD - 119.8 Centerline to sprocket
shoulder - 35.3

Shimano 7600 (large flange) : Nominal OLD - 120 Measured OLD - 120.1 Centerline to sprocket
shoulder - 35.4

Suntour Superbe Pro (large flange) : Nominal OLD - 120 Measured OLD - 119.3 Centerline to sprocket
shoulder - 35.5

These are all hand-held measurements with a less-than-laboratory-grade measuring tool, and the
sample is only one or two of each model. The measurements I took of some other hubs that are in your
table (Miche, Suzue Pro Max and Pro Max-SB) were within a gimme of the numbers you posted, so the
data above should have at least some relevance.

A couple of comments/questions on the information you posted:

By the standard you use, I would think the Miche hubs would qualify as being "adjustable"
for chainline. For what reason did you classify them as not so?

I don't often deal with Suzue's cheapest model (your page calls it the "Basic"), but the
latest generation of these hubs I've seen (from QBP) have come spaced at 120 OLD. There may
be older stock still in the supply chain from EAI and other distributors with hubs
configured at the 117 spec you note.

Thanks again for a cool Valentine's Day gift!

John

- - - - - - - - - - - - - - - http://www.businesscycles.com John Dacey Business Cycles
Miami, Florida
- - - - - - - - - - - - - - - Now in our twentieth year. Our catalogue of track equipment: seventh
year online

 

On Fri, 14 Feb 2003 12:35:50 -0500, John Dacey <[email protected]> wrote:

>In a Valentine gift to us all, Sheldon Brown <[email protected]> wrote:
>
<snip>
>>The tables of sprockets, freewheels and hubs are at:
>>
>> http://sheldonbrown.com/gloss_ca-m.html#chainline1
>>
>>I welcome additional data points from readers.
>
>Thanks for assembling this important resource. Here follows some measurements I took of some hubs
>not mentioned in your tables:

<snip>

Sorry, I forgot to add the sprocket info to my prior post:

Campagnolo Nominal width - 3/32" (2 mm) Measured width - 2 mm Total thickness - 8 mm Thread
thickness - 7.8 mm Chainline from shoulder - 7 mm

Campagnolo Nominal width - 1/8" (3 mm) Measured width - 3 mm Total thickness - 8 mm Thread thickness
- 7.2 mm Chainline from shoulder - 6.5 mm

- - - - - - - - - - - - - - - http://www.businesscycles.com John Dacey Business Cycles
Miami, Florida
- - - - - - - - - - - - - - - Now in our twentieth year. Our catalogue of track equipment: seventh
year online

 

John Dacey wrote:

>>Thanks for assembling this important resource. Here follows some measurements I took of some hubs
>>not mentioned in your tables:

Thanks, John, I've added your data to mine at:

http://sheldonbrown.com/gloss_ca-m.html#chainline1

Sheldon "Chiffres" Brown +------------------------------------------------------+
| If I have been able to see farther than others, | it was because I stood on the shoulders of
| giants. | -- Sir Isaac Newton |
+------------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

Sheldon,

A variation on the theme. I am in the process of converting one of my bikes to fixed wheel. I am
planning to utilise a hub designed to take a six speed block (hence no lock ring - not enough
exposed thread. I will keep both brakes). What is the best way to go to achieve the optimum chain
line. Is it to re-dish the wheel to minimise the asymmetry or to use asymmetric spacers to
centralise the wheel. Both seem possible. Additionally it seems that bottom bracket spindle length
is another variable to consider.

Graham. "Sheldon Brown" <[email protected]> wrote in message
news:[email protected]...
> Today I entertained myself by measuring a bunch of hubs, sprockets and singlespeed freewheels.
>
> I discovered that there is considerably less standardization in terms of chainline than I had
> supposed, and that if you want to get it right, a bit of extra care may be called for.
>
> I've put my data into the Chainline entry of my Bicycle Glossary, though this may at a later date
> grow into a stand-alone article on single speed chainline.
>
> The main Chainline entry is at:
>
> http://sheldonbrown.com/gloss_ca-m.html#chainline
>
> The tables of sprockets, freewheels and hubs are at:
>
> http://sheldonbrown.com/gloss_ca-m.html#chainline1
>
> I welcome additional data points from readers.
>
> Sheldon "Numbers" Brown +----------------------------------------------------------------+
> | Anyone who cannot cope with mathematics is not fully human. | At best he is a tolerable
> | subhuman who has learned to wear | shoes, bathe, and not make messes in the house. | --Robert
> | A. Heinlein |
> +----------------------------------------------------------------+ Harris Cyclery, West Newton,
> Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts
> shipped Worldwide http://captainbike.com http://sheldonbrown.com

 

Graham Steer queried:

> A variation on the theme. I am in the process of converting one of my bikes to fixed wheel. I am
> planning to utilise a hub designed to take a six speed block (hence no lock ring - not enough
> exposed thread. I will keep both brakes). What is the best way to go to achieve the optimum chain
> line. Is it to re-dish the wheel to minimise the asymmetry or to use asymmetric spacers to
> centralise the wheel. Both seem possible.

You need to do both of these things together. Move spacers from right to left to correct the
chainline, then tighten left side spokes to bring the rim back to the centerline of the frame.

> Additionally it seems that bottom bracket spindle length is another variable to consider.

Most double chainwheel setups have the inner ring in about the right position.

Best way to do this is by the numbers. Measure the chainline in front with a ruler held against the
seat tube. Measure from the middle of the seat tube to the points of the chainwheel teeth.

Measure the rear spacing in back. Divide this by two, subtract the front chainline and the resulting
number is how far in from the right dropout/locknut the rear sprocket should be.

Sheldon "Chainline" Brown Newtonville, Massachusetts +--------------------------------------------+
| To see what is in front of one's nose | needs a constant struggle | --George Orwell |
+--------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone
617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

On 2/14/03 16:41, in article [email protected], "Sheldon Brown"
<[email protected]> wrote:

> Graham Steer queried:
>

>
>> Additionally it seems that bottom bracket spindle length is another variable to consider.
>
> Most double chainwheel setups have the inner ring in about the right position.

While this is true, you certainly can use a shorter BB spindle and put the chainring on the outer
position instead.

Most of my fixed gear bikes are set up with older shimano cranks that typically took a spindle in
the 113mm+ range run on the 107mm spindle that is more common with later crank models.

Baird

--
Baird Webel Washington DC

 

Graham Steer wrote:
>>
>>>Additionally it seems that bottom bracket spindle length is another variable to consider.

I wrote:

>>Most double chainwheel setups have the inner ring in about the right position.

Baird Webel wrote:

> While this is true, you certainly can use a shorter BB spindle and put the chainring on the outer
> position instead.

No, not "certainly" but sometimes you can do this.

> Most of my fixed gear bikes are set up with older shimano cranks that typically took a spindle in
> the 113mm+ range run on the 107mm spindle that is more common with later crank models.

Most people converting a road bike to fixed gear, reusing the old crank, would rather not buy a new
bottom bracket if they could use the old one.

I did do this when I set up my Raleigh/Baylis, with an older Dura-Ace crank, but I needed to buy a
new BB for that anyway, since I was building up from a bare frame.

The chain line could be better, but it does look nicer this way, and the tread ("Q factor") is
narrower this way.

Sheldon "http://sheldonbrown.org/raleigh-baylis" Brown
+-------------------------------------------------------------+
| The reasonable man adapts himself to the world; the | unreasonable one persists in trying to
| adapt the world | to himself. Therefore all progress depends on the | unreasonable man. --
| George Bernard Shaw |
+-------------------------------------------------------------+ Harris Cyclery, West Newton,
Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts
shipped Worldwide http://captainbike.com http://sheldonbrown.com

 

graham-<< I am in the process of converting one of my bikes to fixed wheel. I am planning to utilise
a hub designed to take a six speed block (hence no lock ring - not enough exposed thread. I will
keep both brakes). What is the best way to go to achieve the optimum chain line.

Start with a hub and small ring on the inside of the crank. Put the crank/ring on the bike and then
the rear hub...move spacers around on the hub until you get a straight chainline, then measure the
hub and build the wheel.

<< Is it to re-dish the wheel to minimise the asymmetry or to use asymmetric spacers to centralise
the wheel.

If the wheel is already built, do the same thing. Move spacers from the right to the left, which
moves the rim right-a good thing...until you get a straight chainline, then redish the wheel, by
raising the tension of the left spokes, a good thing..

<< Additionally it seems that bottom bracket spindle length is another variable to consider.

Not if you start with a road crank and then put the ring on the inside with track chainring bolts-I
did this with a C-record crank, a 42t ring...use a 16t in the rear.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"