Appropriate canti/v-brake bosses + fork construction

[false_aesthetic]

Hey folks,

A friend is asking for some help bringing an early 2000s Klein back from the dead. His request: segmented fork w/brake bosses. I've made about a dozen forks (4 of which are segmented) but I've never had the "luxury" of worrying about canti/v-brake studs + their placement.

I could use a bit of guidance here:

1. Shimano tech docs are saying that the bosses should be spaced 80mm apart (C-C). How much "wiggle room" is there to this number? I came to riding at the tail end of v-brakes but it seems like rim width and brake selection might affect the final placement.

2. My current drawing is telling me that I have have 24mm between the center of the fork blade (1.125"/28.6mm diameter) and the center of the boss. Is there/was there an appropriate brake boss made or at least one that'll get me close? If not, that's fine, I can adjust the design and sleeve/alter bosses as necessary.

3. Any "whammies" I should be aware of as I walk into this?


Thanks for schooling me on "ancient tech."

[Andrew R Stewart]

1- Rim width (outside, not internal like a tire sees) effects boss c-c. This is way I shake my head when c-c is stated with no rim data. Best is to have the brakes on hand to mock up and/or check final boss placement.

2- Unsure as to this. But remitering a boss isn't hard. I have added a larger diameter sleeve/tube to the base of machined bosses to gain blade miter contact surface area.

3- the usual "I forgot to think about..." stuff. Sounds like the tires will be wide. Take care that the pads clear the tire sidewall as they release from the rim. Where the boss center is relative to the tire's bulging out from the rim and the arc the pads travel through can be tricky. Andy

[steve garro]

26" ?

253.5 mm center of brake spigot to center of axle, 70-75mm center to center of spigots and that's not very negotiable at all.
Rim width does matter, and you have two spigot offsets (commonly) 9mm & 13mm

Dropout OLD is 100mm - 13mm x 2


- Garro.

[false_aesthetic]

Hey Thanks for the responses (and apologies for my delayed response)
@Steve Yep its a 26" tire. Your "Y-axis" measurement is spot on with what I have.

It's the C-C measurement for spigots that is a bit confusing to me. Can you confirm that I'm thinking about calculating the spacing correctly?

C-C spacing = 2(B+S) + W (Image below)

B = Center of brake spigot to edge of pad
S = Desired space between pad + rim
W = Outside rim width.

If this is correct and if I'm limited to a 9mm or 13mm offset I can work backward from there.

Much appreciated!

forkish.jpg

[steve garro]

Hey Thanks for the responses (and apologies for my delayed response)
@Steve Yep its a 26" tire. Your "Y-axis" measurement is spot on with what I have.

It's the C-C measurement for spigots that is a bit confusing to me. Can you confirm that I'm thinking about calculating the spacing correctly?

C-C spacing = 2(B+S) + W (Image below)

B = Center of brake spigot to edge of pad
S = Desired space between pad + rim
W = Outside rim width.

If this is correct and if I'm limited to a 9mm or 13mm offset I can work backward from there.

Much appreciated!

forkish.jpg

You also have two washer thicknesses to work with there............you're getting it..........also, it it's Paul Components they seem to run more like 80mm

- Garro.

[Jonny Cycles]

Yeah, like Steve said: you're getting it. I eliminate "S" dimension from my setup. I set the post spacing such that the brake arms are in the perfect orientation when the pad contacts the rim (usually vertical for linear pull brakes).

[false_aesthetic]

Thanks ya'll.

Parts ordered.

No whammies.