Fixed Wheel and Single Speed Bicycle FAQ's (part 2)

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VeloSolo Fixed Wheel And Singlespeed Frequently Asked Questions - part 2:

If you find this guide useful please do remember to rate our guide at the base of this page - thank you!

c) Set-up questions:

1. Which (drilled cog) hub/set-up is best for my singlespeed road/track bike?
2. Which (drilled cog) hub/set-up is best for my mountain bike?
3. Tell me more about chainline.
4. So what will my chainline be if using a cog mounted on a disc hub?
5. How do I adjust my chainline then?
6. Tell me more about frame spacing.
7. Tell me more about wheel dishing.
8. Tell me about the various types of drop-outs.
9. Use a Shimano hub?! On my fixie?! 
10. Do all normal threaded track hubs and cogs have the same chainline? 
11. Any tips for installing traditional threaded cogs on track hubs? 
12. Left-hand drive - what's that all about?
13. Can I use the bolt-on cogs for a double-fixed (Surly 'Dingle' style) set-up?

1. Which (drilled cog) hub/set-up is best for my singlespeed road/track bike?

First ensure you can run a fixed wheel with your frame - see above.

Yes? OK - frame spacing, this determines the best choice in hub. The most common spacing on track and SS specific frames is 120 mm. This is the modern standard that virtually all track frames and single speed road bikes are made to.

By far the best choice for a hub to utilise a VeloSolo bolt-on cog is a mountain bike front disc hub, specifically a Shimano M756 disc hub or similar.  Why this hub? See question below: Use a Shimano hub?! On my fixie?!

In short the hollow QR axle can be replaced with our custom solid axle and spacers allowing the hub to fit perfectly into the standard rear track/singlespeed road frame width of 120 mm.

Normal chainline on a track/singlespeed road bike is approximately 42mm. A cog mounted on a disc hub as above will give a chainline of approximately 41 mm.  It is a simple matter to add spacers or washers between cog and hub to dial in the chainline perfectly to exactly match your front chainset. For instance adding a 1mm spacer makes your chainline 42mm, adding a 2mm spacer will make it 43mm.

If you are not concerned about using a track chainset or keeping the 42mm chainline then a superb alternative set-up all round is to use the same M756 hub but place a 5mm spacer on the drive-side and a 15mm spacer on the non-drive side. Not only will this give you a non-dished wheel it will give a chainline of approx 46mm.  This matches perfectly the outer ring position on a standard road chainset (46mm).  Thus a world of second-hand or new road chainsets and bottom brackets from Campagnolo, Shimano etc becomes usable.

If you have an older road frame with horizontal dropouts designed to be used with gears the rear frame spacing will probably be 126mm or 130mm. Most of these older frames will be steel which can happily be squeezed in or out a few millimetres.

If spacing is 126mm use the set up as per a road/track frame with 120mm spacing and add another 3mm of spacers or washers each side (see shop) or you could squeeze the dropouts together as you tighten the wheel nuts - steel will not complain. Chainline in this situation will be the same as a 120mm spaced frame.

If spacing is 130mm on your frame then simply add another set of 5mm CNC spacers to the hub taking it from 120mm to 130mm.  If a steel frame then another option is to use a 135mm mountain bike rear hub and spring the dropouts apart slightly.  This gives the advantage of being able to use a flip/flop fixed/free set up. Chainline in this situation would be around 53mm so a longer bottom bracket or a mountain-bike chainset may be necessary.

Some older track/Keirin frames use 110mm rear spacing. In this case just use a 5mm spacer each side. Chainline will be approx 41mm, or place both 5mm spacers non-drive side for a 46mm chainline. For more on spacing the hub see also: Tell me more about frame spacing and Tell me more about wheel dishing.
  
2. Which (drilled cog) hub/set-up is best for my mountain bike ?

First be sure you can run a fixed wheel on your frame. See above questions.

Yes? Great - the route to fixed is easy. The rear spacing on virtually all mountain bikes is 135 mm. The best set up is a normal rear cassette hub with 6 bolt disc mount - you probably have one of these on your mountain bike right now.

By mounting a drilled cog on the disc mount and a normal singlespeed cog and spacers on the freehub side you have a flip/flop fixed/free wheel (see pic below). As simple as that, no alterations are necessary and the wheel can be used with gears again simply by removing the singlespeed cog and mounting a cassette.

Using a cassette wheel with a single cog and spacers allows the chainline on the freehub side to be adjusted to match the fixed side perfectly. Thus when flip/flopping the wheel your chainline stays spot on.  A cog mounted on the disc side will in most cases give a near perfect chainline with the outer front ring.

Or use a standard mountain-bike singlespeed (ie screw on freewheel)  6 bolt disc hub.

3. Tell me more about chainline.

On a singlespeed or fixed wheel bike you want the chain to run in as straight a line as possible. Ideally the two measurements; from the centre of the frame (at the seat tube) to the front chainring and again from the centre of the rear dropouts to the rear cog should be within 1 or 2 millimetres of each other.

This measurement is your chainline front and back. Standard chainline measurements are as follows:

  • Track and singlespeed road = 42mm
  • Road double inner ring /outer ring = 41mm/46mm
  • Singlespeed mountain bike = 54mm
  • Mountain bike triple; middle ring/outer ring = 48-50mm/52-54mm

These are standard measurements but in practise chainline often (nearly always) varies from these numbers and is rarely spot on front and back.  Always measure your own chainline to be sure.  See Sheldon for more on chainline.

4. So what will my chainline be if using a cog mounted on a disc hub?

Chainline will be as follows:

  • M756 disc hub converted to fit on rear of road bike with 10mm spacer each side (slightly dished wheel) =  approx 41mm
  • As above but with 5mm spacer drive side, 15mm spacer non-drive side (non-dished wheel) = approx 46mm
  • Bolt on cog to rear disc hub on a 26&quot/29er mountain bike = approx 53mm

 5. How do I adjust my chainline then?

Compare the measurements in questions 3 and 4 above - simply add 1mm or 2mm spacers between hub mount and cog to create a perfectly matched chainline with the chosen chainset.  If using traditional threaded track cogs you can mount spacers between the cog and the shoulder of the hub, please see track cog section of the shop.
 
There are other ways - use a longer/shorter bottom bracket (BB) spindle or spacers on the BB cups. Use a different chainset or mount the chainring in a different position.
 
6. Tell me more about frame spacing.

Frame spacing is simply the distance between the inner face of the rear dropouts. Common measurements are as follows:

  • Track, singlespeed road frames and some old 5 speed frames = 120mm
  • Some older track/Keirin frames = 110mm
  • 6 and 7 speed road frames = 126mm
  • Modern 8/9/10 speed road frames = 130mm
  • Mountain-bike 26&quot and 29er frames = 135mm

As always see Sheldon for more on frame spacing.

7. Tell me more about wheel dishing.

If you space a M756 disc front hub (100mm spacing) with 10mm of spacers each side to fit on the rear of a road frame then the chainline will be approx 41mm. The wheel will be slightly dished due to the disc mount.

If you want a non-dished wheel simply add a 5mm spacer to the drive side and 15mm (10mm + 5mm) on the other side. Chainline will be approx 46mm.

A road double chainset with just one ring in the outer position works brilliantly here as the normal chainline for this is 46mm. This also gives you access to endless options of chainsets and plenty of superb value second-hand Campag lovelyness on ebay.

8. Tell me about the various types of drop-outs.

There are three main types of rear drop-out with many minor variations: vertical drop-outs, horizontal drop-outs and track ends.

Most older road bikes and much older mountain bikes have horizontal dropouts, most newer road and nearly all modern mountain bikes use vertical dropouts.

Singlespeed specific bikes (road and mountain) mainly use track ends but you will also find sliding or adaptable dropouts on many singlespeed mountain bikes of recent years.  Pictured below are the three common types of drop-outs, see Sheldon's site for more.

9. Use a Shimano hub?! On my fixie?!

Hey, we love Campagnolo etc as much as the next man, and use it wherever we can.  However, you have to hand it to the big 'S', if you want an excellent quality strong hub, that is affordable, adaptable, easily serviceable anywhere in the world, will roll and roll for years and converts to fit a bolt-on cog to a road bike in minutes then XT's legendary M756 hub is perfect.
 
The M756 XT hub has double seals, superb user servicable bearings with borozon polished races and is wide bodied and high flange to build into a strong, stiff wheel.  Importantly it also takes a 10mm axle, thus, the hollow QR axle can be replaced with a solid axle to take track nuts.

This allows custom spacers to be added each side to take the hub width from the standard front wheel width of 100mm to the standard rear track/singlespeed frame width of 120mm.  More spacers can be added to custom fit the hub exactly to your particular frame, be it 110mm, 126mm or even 130mm.

If you really dislike the Shimano name then our lovely special order polished hubs make the XT logos barely visible.  Check the pics in the shop and gallery to see how 'factory' the various converted hubs look.

10. Do all normal threaded track hubs and cogs have the same chainline?

No.  There is a rough standard of 42mm but due to variations in hubs and cogs you will find chainline with threaded track hubs and cogs can vary from 40mm to 46mm or more.  The best information is on Sheldon's site, if you scroll down a little to the chart; 'Fixed Sprockets and Single Freewheels' and look at the 'Chainline Center to Shoulder' on the hub chart you can see that the distance to the hub shoulder (against which the cog mounts) for common hubs varies from around 35mm  (Suzue) to nearly 40mm (Goldtec).  The similar chart shows the chainline for cogs varies from 5mm to 7mm.  To find the actual chainline you add together the two measurements for the combination you are using.  Thus a Goldtec hub with a 1/8" EAI cog would have a chainline of over 46mm.  A Miche track hub with a 1/8" Campag cog would have a chainline of around 43.3mm.

Taking a VeloSolo threaded cog it has an overall width of 7.5mm with the shoulder on the inside.  The tooth thickness (on a 1/8" cog) is 3.0mm.  Thus the centre of the cog teeth (ie chainline) is 1.5mm from the outside or 6.0mm from the inside of the shoulder.  To find out what the chainline would be on your hub add 6.0mm to the 'Chainline Center to Shoulder' hub dimension on Sheldon's chart above.  The average is around 36mm giving a standard 42mm chainline.  You can fine tune this by using spacers between the cog and hub shoulder as long as enough thread is available.  Phew!  Hope that all makes sense.

11. Any tips for installing traditional threaded cogs on track hubs?

To start with ensure all threads are perfectly clean; on hub, cog and lockring.  Lightly grease the hub threads and start the cog by hand.  If it does not go on with the lightest effort back off and start again ensuring it is not cross-threaded.  Spin the cog right up to the hub shoulder and using a chain whip crank it up really tight.  Repeat with the lockring and tighten securely with a lockring tool, remember the lockring has a left-hand thread and tightens anti-clockwise.

Now go ride round the block and up a few steep bits cranking good and hard.  You should find the cog has tightened up some more so you will need to re-tighten the lockring.  Check it from time to time.  Always use a well fitting tool to avoid damage to the lockring notches.
 
As well as the traditional method of installing cogs there is an alternative known as 'rotafix' - a Google search will bring up more on this.  If  rotafixing though take care not to over-tighten things.

12. Left-hand drive - what's that all about?

It's just something a bit different and that the bolt-on cog makes possible.  BMXers' have been doing it for years.  Easy to set-up but there can be an issue with the pedals trying to unscrew as they are now threaded the 'other' way round to normal, a drop or two of Locktite and regular checks should solve that.  Please see the gallery for some LH drive set-ups.
 
13. Can I use the bolt-on cogs for a double-fixed (Surly 'Dingle' style) set-up?

For our dedicated page on this please check: dual VeloSolo Disc cog set-up.

If you have found this guide useful please do remember to rate our guide at the base of this page - thank you!

VeloSolo 2011

Please visit the VeloSolo ebay shop for over 150 fixed and singlespeed products

Please see Part 3 for: Other technical and miscellaneous questions

Please see Part 1 for: General Fixed FAQ's & Can I run a fixed wheel on my bike?

 

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