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View Full Version : Tap-in V-Brake Mounts - Opinions Sought.



DannyC
08-24-2013, 11:52 AM
Hi Folks,

Against my personal preference I let myself get talked into allowing my V-Brake bosses to be welded to the underside of the brake-arms on my StreetFox.
This may be a sounder engineering solution (allegedly as the V-Brakes are being pushed onto the brake-arms and not away from the brake arms).
http://s5.postimg.org/86lrcibfn/P1010541.jpg (http://postimg.org/image/86lrcibfn/) http://s5.postimg.org/pxxdqyqub/P1010542.jpg (http://postimg.org/image/pxxdqyqub/)

However, this also means that the brakes are more difficult to work on (under the brake arms) and the "pretty" side of the alloy is not on show, only the "ugly" side.

Rather than cut the brake mounts off and re-weld on the top-side (spoiling my beautiful paint-job), I wondered if I could use > these (http://www.ebay.co.uk/itm/2pcs-M8-V-Brake-Bosses-Post-6AL-4V-Ti-Titanium-in-11g-/130526721371) < and drill and thread my StreetFox brake arms on the upper surface.
The material of the Brake arms is 2.5mm thick, but these are my brakes, I just wondered if it would be "safe and secure" enough to trust my life to?

Any experience/thoughts on this type of mounting guys?

Regards,

Dan.

IrvJamison
08-24-2013, 12:03 PM
How about some black paint as then they would blend into the frame and not stand out so much or some shrink-wrap?

darnthedog
08-24-2013, 02:09 PM
Danny,Danny Danny- Your friend should have looked at a regular Bicycle to realize that the front Brake on an Upwrong are mounted to be pulled away from the frame as well. I guess that's what happens when over thinking build.
If you wanted to move the placement I don't believe there will be an issue. I am unsure of the screw in method so I cannot comment on that. But should you build in future take normal bicycles into consideration and how they mount things.

Tradetek
08-24-2013, 05:30 PM
Um... DTD, unless I missed something in the description of the problem here, mountain bike brakes are normally mounted on facing away from the frame, ie. front of the fork, back of the seat stays.

The primary difference is the orientation and adjustment of toe-in of the brake pads.

Functionally, there is no benefit to either side, because the pads have to be adjusted properly to their orientation to be effective. Once adjusted properly, they work the same regardless of brake arm orientation.

What Dan has here is a decision on aesthetics.

Dan, keep in mind that those studs need to be screwed into something. I don't think that screwing them through one surface of a hollow tube is going to be sufficient.

Bill

DannyC
08-24-2013, 06:04 PM
Thanks everyone for the responses, your input is greatly valued.
On any push-bike I've ever seen the brakes are indeed on the outside of the frame (for ease of maintenance if nothing else).
This means that the front-brake (the one that really does 70%+ of the work) is being "pulled" away from the frame and it never does any harm.
I thought the argument was spurious, I should have stuck to my guns.
I will live with them on the underside for now (unless it becomes a big problem) and then perhaps move them later.
The most important bit is to get the bike on the road and ride it :-)

Regards,

Dan.

Tradetek
08-24-2013, 07:45 PM
I realize that I didn't really point this out Danny... but you want to make sure that you adjust the brake pads as it they were on the back of regular bike.

Bill

Ticktock
08-24-2013, 10:34 PM
It also means you will have one cable on the inside, and one cable on the outside of the wheels. unlike the older style callipers, your side pulls cannot be rerversed on the studs.
To get neat cabling you will need one side on top and the other below the arm. Unless someone knows a trick I have not learnt yet.
The brakes work with either direction, just as on a normal bike.
Steve G

DannyC
08-25-2013, 06:44 AM
Thanks all.
Bill, by "adjust as if on back of bike" I assume that you mean the toe-in of the pads to ensure they flatten out on the rim as they are applied and the wheel pulls them further into contact?

Steve, yes, cable routing is indeed going to be problematic, I need a "SuperNoodle" LOL.

Regards,

Dan.

Ticktock
08-25-2013, 08:38 AM
I'm more worried that a cable hanging outside the wheel is going to get caught on something, with really bad results for either you , or it , or both.
By placing one side high and one side low you can keep both cables inside the wheels, where they should be.
But I would not trust tapped in studs--only good brazing or mid-strength welds on that one! (forgot to add that in the last post--sorry)
I have a similar set up on the back of my tandem, but with old style calipers, where the cable direction can be reversed--a noodle will get round that problem for you.
In my case the brakes work equeally badly due to wrong lever choice, but with the correct lever you should have no problems with a reversed set up.
Here in Beijing, a stray cable would be a liability even when parked!!
Steve G

Tradetek
08-25-2013, 10:03 AM
That's correct Danny.

DannyC
08-25-2013, 01:49 PM
Well, thanks all of you guys,

I am really glad to have started this thread and to have had so many intelligent and coherent responses.
I have decided to make a minor change "on the fly" and use some alternate "old" V-Brake arms that are pressed-steel rather than cast alloy on both front wheels.

http://s5.postimg.org/cr3sx2moz/P1010544.jpg (http://postimg.org/image/cr3sx2moz/)

I believe that I will be able to reverse the role of the arms of one of the pair of the V-Brake arm sets by filling in an existing hole with weld, drilling-out and and pop-riveting in one side and filing out the other to suit.
This will enable the brakes on both wheels to be cabled from "inside" the bike's boundaries and with no external cable overhanging the outside of the bike to catch on to snags & pedestrians etc.

This should fix all issues and create a neater cabling solution.

Regards,

Dan.

Ticktock
08-25-2013, 07:45 PM
Now you are a fully qualified Zombie---no stoping you now! Uhm--bad choice of words--the brakes will stop you and the bike--no holding you back once you start modifying things.
Steve G

Tradetek
08-26-2013, 12:17 AM
Sounds like a good idea, keep us updated on your experiences and final product.

Bill

Ticktock
08-26-2013, 08:40 AM
Hi Danny,
Just a comment to avoid confusion about an already confusing subject.! your brakes are "side pulls" , not Vee pulls (AKA Center pulls) . So now what do we call the Old style calipers that also pull from the side??? Don't ask me, I just buy them when I need them--like "them ones there", works well in China!
Apart from the obvious difference in the way Vee pulls work compared to Side pulls the sneaky bit is that the studs are in slightly different positions, so they just work, but you don' get much wear before they don't work, either way round when you mix them up.
Steve G

DannyC
08-26-2013, 11:45 AM
Thanks Steve, I am only recently returned to cycling so all these new-fangled things are alien to me.
But, I think I am correct (or at least Mr. Wikipedia tells me so).....see below.

V-brakes[edit source (http://en.wikipedia.org/w/index.php?title=Bicycle_brake&action=edit&section=16) | editbeta (http://en.wikipedia.org/w/index.php?title=Bicycle_brake&veaction=edit&section=16)]
http://upload.wikimedia.org/wikipedia/commons/thumb/a/ac/Linear_pull_bicycle_brake_highlighted.jpg/170px-Linear_pull_bicycle_brake_highlighted.jpg (http://en.wikipedia.org/wiki/File:Linear_pull_bicycle_brake_highlighted.jpg)
http://bits.wikimedia.org/static-1.22wmf12/skins/common/images/magnify-clip.png (http://en.wikipedia.org/wiki/File:Linear_pull_bicycle_brake_highlighted.jpg)
Linear-pull brake on rear wheel of a mountain bike


Linear-pull brakes or direct-pull brakes, commonly referred to by Shimano's trademark V-brakes, are a side-pull version of cantilever brakes (http://en.wikipedia.org/wiki/Bicycle_brake#The_cantilever_brake_design) and mount on the same frame bosses (http://en.wikipedia.org/wiki/Boss_(engineering)). However, the arms are longer, with the cable housing attached to one arm and the cable to the other. As the cable (http://en.wikipedia.org/wiki/Bowden_cable) pulls against the housing the arms are drawn together. Because the housing enters from vertically above one arm yet force must be transmitted laterally between arms, the flexible housing is extended by a rigid tube with a 90° bend known as the "noodle". The noodle seats in a stirrup attached to the arm. A flexible bellows often covers the exposed cable.[15] (http://en.wikipedia.org/wiki/Bicycle_brake#cite_note-15)

http://upload.wikimedia.org/wikipedia/en/thumb/6/60/Bicycle_Noodle.jpg/220px-Bicycle_Noodle.jpg (http://en.wikipedia.org/wiki/File:Bicycle_Noodle.jpg)
http://bits.wikimedia.org/static-1.22wmf12/skins/common/images/magnify-clip.png (http://en.wikipedia.org/wiki/File:Bicycle_Noodle.jpg)
A noodle


Since there is no intervening mechanism between the cable and the arms, the design is called "direct-pull". And since the arms move the same distance that the cable moves with regard to its housing, the design is also called "linear-pull". The term "V-brake" is trademarked by Shimano (http://en.wikipedia.org/wiki/Shimano) and represents the most popular implementation of this design.
V-brakes function well with the suspension systems found on many mountain bikes because they do not require a separate cable stop on the frame or fork. Because of the higher mechanical advantage of V-brakes, they require brake levers with longer cable travel than levers intended for older types of brakes. Mechanical (i.e. cable-actuated) disc brakes use the same amount of cable travel as V-brakes, except for those that are described as being "road" specific. (See Actuation mechanisms (http://en.wikipedia.org/wiki/Bicycle_brake#Actuation_mechanisms) below.) As a general rule, mechanical disc brakes for so-called "flat bar" bicycles (chiefly mountain and hybrid bicycles) are compatible with V-brake levers, whereas mechanical disc brakes intended for "drop-bar" bicycles are compatible with the cable pull of older brake designs (cantilever, caliper, and U-brake).
Cheap or poorly-specified V-brakes can suffer from a sudden failure when the noodle end pulls through the metal stirrup, leaving that wheel with no braking power whatsoever. Although the noodle can be regarded as a service item and changed regularly, the hole in the stirrup may enlarge through wear. The stirrup cannot normally be replaced, so good quality V-brakes use a hard and tough steel for the stirrup.[16] (http://en.wikipedia.org/wiki/Bicycle_brake#cite_note-16)



So, on this basis, is my alleged faux-pas demerit point withdrawn? ;-)

Regards,

Dan.

FrankCrank
08-26-2013, 11:27 PM
What a confusing subject - and just like most bike stuff these days you've gotta keep on top of the terminology or you end up completely flummoxed. The older style brakes that have a centre bolt going through a hole in the crown of the fork come in two types, side-pull and centre-pull, and I think this is what Steve is referring to.

The generic name for the newer brakes is cantilever, and these bolt to the legs of the fork. They also come in two flavours, either with the noodle connector (Shimano V-brake) as per Danny's pics, or with a straddle wire. Of course there are other permutations with subtle differences and other names, but I think they are relatively rare. The straddle wire looks like an inverted 'V', and logic would say that these should be called V-brakes, but Shimano do the noodle type and call them V-brakes instead.........now my head hurts.......

Tradetek
08-26-2013, 11:28 PM
Yes Danny, you have "V" pull brakes.

Steve, I have a feeling that you are thinking of cantilever brakes which use do-hickey (getting technical here term :rolleyes4:) to pull on the center point of a single cable that is attached to both brake arms, right?

Bill

DannyC
08-27-2013, 06:08 AM
I'm glad we now have a common understanding of these wonders of technology. :-)

Don't laugh, I struggle because my first bicycle had rod-brakes (I am that old).

Dan.

Ticktock
08-27-2013, 08:37 AM
Frank, take a break before something breaks, or the brakes break--or something!!!
Steve G

Ticktock
08-27-2013, 08:49 AM
This gets even more fun!
I was aware of , in no real order, but as they appeared on my bikes--Rod Brakes (see you are not the only one), then Caliper (these with a center pivot and the cable on one side) then
Vee pull (AKA Y-pull) where the cantilever arms were pivoted on the forks, and pulled in by a transverse cable with the main cable acting on the center (good brakes as they can be tailored quite a bit ) Side pull, where the two cantilevers are pivoted on the fork legs, and the single cable pulls from the side, usually through a noodly thingy.
I think there was a center pivot caliper that worked like a Vee or Y pull, but not on my bikes. Then came the disc brake.
Now lets have a break from brakes.]
Steve G,
Beijing
By the way, Rod Brakes are so commom here you can still buy new parts for them, or a new bike with rod brakes!!
In my early days, they were simply known as rod brakes or cable brakes--the only two choices you had--a world with no disc brakes!

FrankCrank
08-27-2013, 09:24 AM
....yeah, see lots of those bikes with rod-brakes over here too, some really ancient and some brand new. You often see second hand bike shops here that only sell stuff brought over from Japan - and mostly hugely overpriced. I often stop by if passing and have a perusal just out of curiosity. They usually have a few bright red Japanese postman bikes - real heavy duty things with rod brakes and lugged frames, and the rack looks like it could carry a sack full of car batteries! Them postmen over there must be pretty fit methinks......