Under-Chainstay U-Brake Solution?

[Wolfgang Weiss]

Measure the crown race. ......easiest way.

Iso is standard size....26.4mm

Jis is 27.0mm

Crib sheet here

Sheldon Brown's Bicycle Headset Dimension Crib Sheet

Useful headset (steering bearing) dimensions and conversions for the cyclist/mechanic

www.sheldonbrown.com

Unless its old old old french, its unlikely to be french size..

I don't have caliber so I cannot measure it.

 

[legrandefromage]

May I ask you a question? I bought this frame without a headset and since it's french brand I have a suspicion - it fits french headset or ISO?

Standard threading

 

[Tootyred]

Add it to your Christmas list....cheap analogue(not cheap digital) they are a vital part of pretty much any tool kit, especially if your going to be messing about with stuff like this! £14

Magnusson Vernier Callipers 6" (150mm) - Screwfix

Order online at Screwfix.com. 4-way metric measurement including internal, external, depth and stop. Vernier scale. Plastic case included. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

Or similar.

If your really want to spash out buy a moore and wright pair......for £18

Moore and Wright 110 Series MW110-07 Precision Miniature Pocket Vernier Caliper 0-70mm

0-70mm Precision Miniature Pocket Vernier Caliper - Moore and Wright 110 Series

www.machine-dro.co.uk

No batteries, more accurate as the scale never slips (which it will on cheap digital ones). Be with you for the rest of your life!

 

[legrandefromage]

Here you go

 

[elite504]

Cams for sensible money in the UK.
Considering how much in the firing line for mud an under chainstay brake is, going NOS eliminates the potential for worn bushes and a perpetually squeaky brake

You searched for roller cam • https://www.bicyclist.cc

bicyclist.cc

 

[MuchAlohaNui]

I don't have caliber so I cannot measure it.

Take piece of paper
Precisely wrap around crown race mating surface
Paper edge seated on race surface
Mark overlap w/ sharp pencil
Remove paper
Lay flat
Use ruler with mm
Measure end of paper to pencil line
Divide by 3.14
D = C/pi
All measurements are to three significant figures anyhow
Do this paper thing three times for spatial resolution

 

[Tootyred]

Or just blow £13 .