Flatbar handlebar Common Sizes

This post is about flatbar handlebar common sizes on commuter/urban/flatbar road bikes.

Flatbar or Riser ?
Flatbar is generally pretty straight.
Riser bar is the V-type shape.
For a commuter/flatbar road bike my preference would be flatbar.
So this post is about Flatbars.  

If you have a flatbar handlebar bike.
And want to buy a new flatbar handlebar.
You probably need to work out 2 main dimensions.

The 2 most important specs seem to be :
Stem size.
Width (across)

Flatbar common Stem sizes :
Importance : I think very important (if you can't adjust the fitting for the handle-stem joint.)      

The 2 common flatbar Stem Sizes :
25.4mm (standard)
or 31.8mm (oversized)

There are other sizes but these are the common 2 sizes
Tip :
If your handlebar in the middle looks 'normal sized', it's probably 25.4mm
If your handlebar looks overly big in the middle, it's probably 31.8mm 

Common flatbar widths (across)
Importance : not so important  (?)

Typical flatbar widths :
600mm ?
580 mm would be pretty small.
620mm gives you a bit more space .
The width can go up to 750mm

Note : Riser bars seem to have much wider lengths, such as 750mm
I have read that bars can come big in order to 'saw to size'

Brake types for bikes

Brake Types for Bikes list

brake type	example	take note	retrofit needs
rim	Caliper (most modern ?) V-brake (wire across top) Cantilever (old ?)	weak in wet
disc		strong in wet hydraulic (future standard ?) or mechanical (cheaper)	hub adapter ? (remove spokes ? new wheel ?) fork adapter (fork adapter or new fork with disc fixings ?)
drum/roller/hub	roller is shimano version	niche. needs special hub ? heats too easy ? good in wet ?	need hub on new wheel or remove spokes ? need compatible fork ?

update : none yet

Caliper bike brakes

Above is a table I am using to make sense of brake types for bikes. It could be incorrect. Currently I have 'caliper' rim brakes but thinking of switching the front to either a disc brake or hub brake for more safety. The front brakes seem the most important as I use them about 95% of the time.

Reason for table :
Trying to gather my thoughts as hard to find choices in quick view method. My understanding is 2/10. Will update table when more is known. 

My current brakes : Caliper rim brakes
Thinking of : replacing front with hub or disc.
Brake lever type on my bike : flatbar (MTB brake levers)

Reason for changing :
Rim brakes lose a lot of power in the wet. Disc and roller brakes are not affected by wet. For commuters I think at least the front brakes should be disc (or less likely ... roller).

Decathlon B-Twin brand : 1st place I look for bike components

Decathlon (UK) is a shop I now look at first for bike components. The usual choices for brake and drivetrain components etc are Shimano and Sram and seem to have a decades long duopoly.

Recently I noticed Decathlon have bike components using their B-Twin branding. I trust this shop and they have a casual returns policy, and they also tend to offer quality products as their own brand at much cheaper prices than alternatives.

So currently they are my first point of reference when looking for anything to do with cycling including clothes

There are only a few stores in the UK. They have the same type of store presence as IKEA.

Decathlon UK Cycling dept

Items I have bought

7/8 speed 11-34 tooth rear derailleur : £7.99
to replace Shimano

V-brake pads