Upgrading Brakes - advice please

[mill4six]

Mick I have a new roller brake hub languishing in a drawer, I bought it cheap as a spare for the frankenbike. You are welcome to use it meanwhile to save Barbarella. Let me know Simon...

[531colin]

http://wwwstagonset.co.uk/fasteners?car ... Lnd&summit

EDIT cant get link to work-- scroll down home page picture board for rubber lined P clips

[Mick F]

Thanks guys.
Mrs Mick F has given me permission to rob Barbarella of her front hub.
SJS have emailed with ERD for their 305mm rim.
All that is needed now is for me to find the calc for the spoke-lengths and order rim and spokes. Easy done.

Thank you FW for the offer of metalwork and advice.
Thank you Simon for the offer of a Roller Brake hub.
Thank you Colin for the P clip link - that didn't work, but I get your point.

I should be ok for now with the stuff I have. Fingers crossed.

Strip Barbarella - (that takes me back to the film!)- and see how it goes.
http://www.youtube.com/watch?v=SsPkQt2H4YQ

[Mick F]

Head scratching this morning. I think I'll take off Choppers forks and operate on them without being encumbered by the rest of the bike. Sitting here with a cuppa to warm up - it's FREEZING outside and in the workshop!

Mick I have a new roller brake hub languishing in a drawer, I bought it cheap as a spare for the frankenbike. You are welcome to use it meanwhile to save Barbarella. Let me know Simon...

I'll carry on for now, but ta for the offer. If my experiments are successful, I'll PM you as Barbarella is looking very sorry for herself!

[Mick F]

It fits!

[mlteenie]

I would like to add that when I rebuilt my Raleigh Twenty hubs onto new BMX rims (the thread is on here somewhere), the braking was still terrible, even with new v-pads. I haven't yet got round to trying newer calipers than the originals, but one day I shall cough up for some deep drop dual pivot numbers....

[Mick F]

I've yet to try out the new leather-faced blocks, but I reckon that chrome/steel and stopping in the wet don't go together. It has to be better than just rubber, though.

I've ordered the rim and spokes - I await their delivery, and then I'll assemble the wheel and report back.....

[Mick F]

Wheel is built!
36h 2x

Small wheels are so much easier than large ones. I can thoroughly recommend getting the hang of wheelbuilding using smaller wheels.

Please note, I got the valve in the right place too!

Next job is to reassemble Chopper and go for a test-ride. I may go and collect my new leather blocks. Hopefully, they will only be needed for the rear, as this rollerbrake should do the biz.

[mlteenie]

Blimey, Mick. You don't hang around! Looks great.

[SA_SA_SA]

hub brakes are more powerful in small rims (less leverage).

[Mick F]

Blimey, Mick. You don't hang around! Looks great.

Thank you!
Nice, isn't it.

hub brakes are more powerful in small rims (less leverage).

Yes.
I spent ages talking to a chap the other evening about braking. Rim versus Hub ............

We eventually agreed that rim brakes are not concerned with diameter of the wheel. The larger, the more leverage. Also, as the axle is always in the centre, the leverage is the same no matter what the diameter.

Hub/disc/roller brakes are diameter-dependant. The larger the diameter, the more leverage exerted onto the hub. The larger the diameter of the hub brake with respect to the wheel size, the better.

I should be better with this new rollerbrake on a 16" wheel than I would be on a 27" wheel.

Stand by for another report.

[531colin]

Blimey, Mick. You don't hang around! Looks great.

Thank you!
Nice, isn't it.

hub brakes are more powerful in small rims (less leverage).

Yes.
I spent ages talking to a chap the other evening about braking. Rim versus Hub ............

We eventually agreed that rim brakes are not concerned with diameter of the wheel. The larger, the more leverage. Also, as the axle is always in the centre, the leverage is the same no matter what the diameter.

Hub/disc/roller brakes are diameter-dependant. The larger the diameter, the more leverage exerted onto the hub. The larger the diameter of the hub brake with respect to the wheel size, the better.

I should be better with this new rollerbrake on a 16" wheel than I would be on a 27" wheel.

Stand by for another report.

You sure about that? OK. a 27" wheel exerts more leverage on a hub brake than a 16" wheel, but conversely the hub rotates quicker in a 16" wheel for a given road speed, so the difference in braking performance is actually equal to the difference in stretch of the spokes at the two different lengths......

Sorry, I just couldn't resist that one!!

[GrahamNR17]

You sure about that? OK. a 27" wheel exerts more leverage on a hub brake than a 16" wheel, but conversely the hub rotates quicker in a 16" wheel for a given road speed, so the difference in braking performance is actually equal to the difference in stretch of the spokes at the two different lengths......

Sorry, I just couldn't resist that one!!

May your god forgive you for what you've just started

[531colin]

Yes, whatever happened to Dave Allen? I always enjoyed his parting shot "may your God go with you."

[Mick F]

....... as I said .....

I spent ages talking to a chap the other evening about braking. Rim versus Hub ............

A wheel rotates on an axle.
The bottom of the wheel is stuck (hopefully) to the road and therefore is at Speed Zero.
The axle is moving forward at a certain speed - 10mph?
The top of the wheel is moving at double that speed - 20mph.

Think of any wheel of any diameter and the above is true:
The top of the wheel is moving at double the speed of the axle
So, for any given speed, the top of the wheel will be double. Therefore a rim brake is as efficient on any diameter wheel.

As for spokes, if you have a small wheel, your spokes are shorter, so are less affected by ovalisation or stretch.