Canti's or V-brakes for new touring frame

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MikeF
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Re: Canti's or V-brakes for new touring frame

Postby MikeF » 23 Feb 2018, 5:36pm

The utility cyclist wrote:
MikeF wrote:
tooley92 wrote:
Me too!
+1 My Tektro hoods I find very comfortable. Shimano could take lessons. :wink: Mini V on the front canti on the rear. Rear brake provides little stopping power on roads and "trails", so it doesn't need to be as effective as the front.

How little? Less so if you put an inferior brake system on and/or pay it no mind.
Sorry but as someone that uses their back brake first to retard speed I don't agree with your summation. Why have two different braking types in any case, it makes no logical sense at all :?
The back brake can never provide the stopping power of a front brake. When a brake is applied weight is thrown forward (even with just applying the back brake) and friction between the rear wheel and the road surface decreases. If the rear brake is applied harder the rear wheel will start to skid, with further loss of braking performance. Even if it is not obviously skidding there will be a certain amount of sliding and additional tyre wear. In certain conditions you need to be cautious about using the front brake, but otherwise the front is by far the most effective brake. See https://www.sheldonbrown.com/brakturn.html. Additionally front tyre wear from braking is minimal compared with that of the rear tyre. In fact I'm not sure why disc brakes are needed at all on the rear - at least for braking purposes.

You need two independent brakes for safety reasons. Completely "logical".
"It takes a genius to spot the obvious" - my old physics master

Psamathe
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Re: Canti's or V-brakes for new touring frame

Postby Psamathe » 23 Feb 2018, 5:47pm

The weight disk vs non-disk had me looking over Surly's web site to check the weight difference between a complete Long Haul Trucker and Disk Trucker - on the assumption they are very comparable other than the brakes. But I could not find and weight on the site!

Ian

Brucey
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Re: Canti's or V-brakes for new touring frame

Postby Brucey » 23 Feb 2018, 6:16pm

dragonrider wrote: I think a 5 year old carbon and a new titanium should be about the same weight...


not necessarily. You need to be more careful than that about how you make comparisons.

The disc brake wheels will inevitably be weaker (in relation to the service loads) or heavier or both. There is no escape from this.

But anyway don't take my word for it you don't want to. IIRC in one of his columns Zinn estimated the increased frameset weight alone to allow discs to be fitted would be in the order of 400g or something. That seems a pretty reasonable estimate to me; there are parts of a disc brake frameset that unavoidably see much, much higher stresses than in a rim brake frameset and you cannot withstand those stresses safely without having more material in there, simple as that.

Of course folk will now pipe up saying "in brand x you can buy 'the same parts' disc and non-disc bits that are the same weight ...etc etc"; well that may have more to do with marketing and manufacturing costs etc than engineering. The bits are not the same and if they are, something is wrong. Today you are just as likely to buy disc compatible frameset parts with the disc mounts absent than buy a fully optimised design for rim brakes, and knowing one way or the other is not easy.

In one case you can make a reasonably accurate comparison and that is with steel forks. A reasonably well optimised design for a steel fork (1" threaded steerer) comes in at ~700-750g. A steel disc brake fork typically comes in about 1200g, and must use a 1-1/8" steerer, probably threadless. The range of such fork weights goes from ~1000g to ~1400g. The difference in steerer weight (on length alone) is unlikely to exceed 100g. So that leaves an extra 400g(+/- 200g) in the disc fork. A similar argument can be applied to any other material, except that it is difficult to know whether any one design is really optimised or not.

BTW I'm not saying that you can't make a nice bike with disc brakes, just that for any given (real rather than imaginary) amount of effort/cost, a rim braked bike would be nicer.

But anyway, d-d-d-d....don't believe the hype.

Its official. :wink:

Image

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Brucey
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Re: Canti's or V-brakes for new touring frame

Postby Brucey » 23 Feb 2018, 6:26pm

Psamathe wrote:The weight disk vs non-disk had me looking over Surly's web site to check the weight difference between a complete Long Haul Trucker and Disk Trucker - on the assumption they are very comparable other than the brakes. But I could not find and weight on the site!

Ian


Apologies if this seems pedantic but without exception, brake manufacturers make DISC brakes not DISK brakes and likewise Surly make a bike called the DISC trucker.

I think that the Disc trucker fork is about 1250g and the non-disc brake version of the fork has mysteriously become heavier since the Disc trucker has been introduced. I suspect that the subcontractor who makes their framesets has standardised on a (heavier) fork blade that will accept a disc brake mount.

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The utility cyclist
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Re: Canti's or V-brakes for new touring frame

Postby The utility cyclist » 23 Feb 2018, 8:04pm

MikeF wrote:
The utility cyclist wrote:
MikeF wrote:+1 My Tektro hoods I find very comfortable. Shimano could take lessons. :wink: Mini V on the front canti on the rear. Rear brake provides little stopping power on roads and "trails", so it doesn't need to be as effective as the front.

How little? Less so if you put an inferior brake system on and/or pay it no mind.
Sorry but as someone that uses their back brake first to retard speed I don't agree with your summation. Why have two different braking types in any case, it makes no logical sense at all :?
The back brake can never provide the stopping power of a front brake. When a brake is applied weight is thrown forward (even with just applying the back brake) and friction between the rear wheel and the road surface decreases. If the rear brake is applied harder the rear wheel will start to skid, with further loss of braking performance. Even if it is not obviously skidding there will be a certain amount of sliding and additional tyre wear. In certain conditions you need to be cautious about using the front brake, but otherwise the front is by far the most effective brake. See https://www.sheldonbrown.com/brakturn.html. Additionally front tyre wear from braking is minimal compared with that of the rear tyre. In fact I'm not sure why disc brakes are needed at all on the rear - at least for braking purposes.

You need two independent brakes for safety reasons. Completely "logical".

I don't need lessons on braking thanks and know that a back brake doesn't give you the same power as the front, that isn't my point, you missed it entirely.
Read again where I said I used the back brake first, that doesn't say I don't use the front sometimes, when braking in emergency or when the back isn't enough for greter rates of retardation I'll use the front. Maybe for you your happy to just use the front brake, I wouldn't, there's more chance of an incident grabbing a massive handful of front than there is the back.

It's all about control, locking up the back wheel is far better than to do so on the front if you have a choice, If you've thought about your braking, planned ahead and don't panic brake, which even the pros do often, then locking up your back wheel is never a thing in any case.
So why on earth would you unbalance the braking amount even more by putting in a different type of brake that offers even less efficiency, that's just dumb thinking with no logical benefit to it whatsoever.
Clearly others think it's acceptable, personally it's something I would never do, the logic of well you don't use the back brake as much or it doesn't ultimately offer as much power as the front is no logic at all.

Colin_P
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Re: Canti's or V-brakes for new touring frame

Postby Colin_P » 23 Feb 2018, 8:23pm

I've just looked up BB7's

The BB7 calipers are 157g (for the heaviest version) and a 160mm rotor is 74g for a 160mm stainless steel (most common) item which totals 231g.

Whereas (randomly and crudely searched for)....

A set of Shimano CX70 cantis is 139g (92g lighter than a single BB7 setup or 184g lighter for a pair.)

A set of Shimano Deore XT V's is 175g (56g lighter than a single BB7 setup or 112g lighter for a pair.)

So my estimation of <200g was quite apt.

For context that is 1/3 of a 600ml water bottle or a cheeky mid ride wee behind a tree :wink:

But as I've said, you pays your money and you don't have to spend it on disc brakes.

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horizon
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Re: Canti's or V-brakes for new touring frame

Postby horizon » 23 Feb 2018, 10:06pm

Colin_P wrote:So my estimation of <200g was quite apt.

But as I've said, you pays your money and you don't have to spend it on disc brakes.


Colin_P: I'm very open to your POV but Brucey's point about the overall effect on the bike still resonates with me. I'm a tourer/transporter in filthy, heavily laden, steep hilly conditions so I should be a natural disc convert. But part of me felt that disc enthusiasts talked too much about the braking and not so much about other effects. Looking at how successful discs are on a car for example isn't completely helpful - weight, balance etc etc and I think for many people this is where the argument lies.

While resources and needs at the present time aren't presenting an opportunity to experiment, I intend at some point to install a BB7 on the front of my load-lugging Sardar (the forks are disc ready) and keep my Thorn disc free and compare the results.
Let's just get Brexit done so that we can get on with the important job of re-joining the EU!

Brucey
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Re: Canti's or V-brakes for new touring frame

Postby Brucey » 23 Feb 2018, 10:27pm

Colin_P wrote:
So my estimation of <200g was quite apt....


Broken maths;

- the frameset is heavier (often in places where you can't see it)
- the brakes are heavier
- they need longer heavier cables to make them work
- the wheel components such as rims and spokes need to be stronger because they see higher loads
- the hubs are heavier

you have only allowed for one out of five things. It is easy to fall into the trap of assuming that if a manufacturer offers two versions of a wheelset with the same name that they are equally strong, and therefore comparing the weights is valid. Nothing could be further from the truth!

Also you should try weighing the parts for real. Very often the quoted weights are what we scientists more accurately call a lie; for example some manufacturers routinely quote caliper weights without pads, without bolts, without post-to-ISO converters, all of which are both included in the kit and needed (obviously).

200g is the stuff of ruddy fantasies.

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MikeF
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Re: Canti's or V-brakes for new touring frame

Postby MikeF » 23 Feb 2018, 10:55pm

The utility cyclist wrote:
MikeF wrote:
The utility cyclist wrote:How little? Less so if you put an inferior brake system on and/or pay it no mind.
Sorry but as someone that uses their back brake first to retard speed I don't agree with your summation. Why have two different braking types in any case, it makes no logical sense at all :?
The back brake can never provide the stopping power of a front brake. When a brake is applied weight is thrown forward (even with just applying the back brake) and friction between the rear wheel and the road surface decreases. If the rear brake is applied harder the rear wheel will start to skid, with further loss of braking performance. Even if it is not obviously skidding there will be a certain amount of sliding and additional tyre wear. In certain conditions you need to be cautious about using the front brake, but otherwise the front is by far the most effective brake. See https://www.sheldonbrown.com/brakturn.html. Additionally front tyre wear from braking is minimal compared with that of the rear tyre. In fact I'm not sure why disc brakes are needed at all on the rear - at least for braking purposes.

You need two independent brakes for safety reasons. Completely "logical".

I don't need lessons on braking thanks and know that a back brake doesn't give you the same power as the front, that isn't my point, you missed it entirely.
Read again where I said I used the back brake first, that doesn't say I don't use the front sometimes, when braking in emergency or when the back isn't enough for greter rates of retardation I'll use the front. Maybe for you your happy to just use the front brake, I wouldn't, there's more chance of an incident grabbing a massive handful of front than there is the back.

It's all about control, locking up the back wheel is far better than to do so on the front if you have a choice, If you've thought about your braking, planned ahead and don't panic brake, which even the pros do often, then locking up your back wheel is never a thing in any case.
So why on earth would you unbalance the braking amount even more by putting in a different type of brake that offers even less efficiency, that's just dumb thinking with no logical benefit to it whatsoever.
Clearly others think it's acceptable, personally it's something I would never do, the logic of well you don't use the back brake as much or it doesn't ultimately offer as much power as the front is no logic at all.
I think you missed my point as well, but never mind, how you brake is your choice. Also you are entitled to disagree with Sheldon and others - people sometime do. :wink: However regardless of what you are doing, the front brake remains the most effective even if you choose not to use it much. For situations where the front brake is likely to lose traction I use it with caution or maybe not all.

Braking is unbalanced by its very nature. Cars, for example, have "unbalanced" front/rear brakes because the same principle applies; most of the braking is applied to the front wheels with the less to the rear ones. Applying too much braking to the rear wheel will increase the tyre wear of that wheel and especially so if it slides. Children often find it fun to do rear wheel slides, but their tyres wear fast.
"It takes a genius to spot the obvious" - my old physics master

dragonrider
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Re: Canti's or V-brakes for new touring frame

Postby dragonrider » 24 Feb 2018, 7:38am

Back to the weights. Whether it is 200gm, 400gm or even a bit more I will take the penalty for the much superior wet and winter braking, and hence safety that discs give me .

“You carries your weight and you takes your choice”!

yostumpy
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Re: Canti's or V-brakes for new touring frame

Postby yostumpy » 24 Feb 2018, 8:31am

My 6d worth.
My old Orange P7 mtb/ ruff stuff, had v brakes, very good, until mud gets twist pad and rim, on a winter weekend ruff stuff, about 6 years ago, the rear rim wore thro, and let go with a bang, just outside Glastonbury.
Upgraded bike to mtb with hydraulic discs, phenomenal stopping power, but bike was more than I needed,
Bob Jackson had tektro cantis, ok in the dry, never took it off road, as it was a bit pretty. But it got written off anyway.
Olive, my Ridgeback World Panorama Deluxe has cable discs. Very good they are. I took it on this years winter weekend ruff stuff, and there was some serious mud. It coped extremely well. Out of about 28 people, 60% had tourers, rest had mtb/ cx. MTbs clogged up, but their brakes were fine, tourers..well those with discs had best of it, thin tyres to slice thro mud, and brakes that worked, but those with canti/ V brakes clogged up, then spend the whole weekend grinding their rims away, Swapping pads for the next morning. So which would I choose..
V brakes.....very good in dry, and wet once water is shed, but introduce mud, and......
Cantis, can be good in dry , can be good in wet, ditto mud/ grime, and judder on the front.
Discs. Brilliant all rounder. Ok there may be a bit of extra weight, not for the purists etc, but they really are good. When I had my Bob Jackson built, it wasn't long before I wished I'd got something with discs. My Olive is really my Do Everything Bike. I know this is now OT, but someone mentioned discs. Having a new HD touring bike 'built' these days for v/cantis, doesn't make sense to me. I'm sure whatever the OP ends up with, they will enjoy , happy days, all.

robc02
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Re: Canti's or V-brakes for new touring frame

Postby robc02 » 24 Feb 2018, 10:19am

Psamathe wrote:The weight disk vs non-disk had me looking over Surly's web site to check the weight difference between a complete Long Haul Trucker and Disk Trucker - on the assumption they are very comparable other than the brakes. But I could not find and weight on the site!

Ian


Surly used to quote the weight of their LHT frame only (no fork) at 2340g and the Disc Trucker at something a bit over 2600g as far as I can remember. So around 300g difference.
They also used to quote separate figures for disc and non-disc forks. I think there was about 150g difference, maybe a bit more.

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horizon
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Re: Canti's or V-brakes for new touring frame

Postby horizon » 24 Feb 2018, 11:12am

yostumpy wrote:Ok there may be a bit of extra weight,


IIUC, what Brucey was saying is that it isn't just the weight but how the whole feel of the bike is affected. For some, that is a price worth paying (and it's very subjective anyway). But it isn't just the weight.

not for the purists etc,

Please can we stop using the word "purist"?

And yes they really are good,

But that isn't the point (AIUI). No-one's doubting how effective they are, just whether they are appropriate on a bicycle.
Let's just get Brexit done so that we can get on with the important job of re-joining the EU!

MikeDee
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Re: Canti's or V-brakes for new touring frame

Postby MikeDee » 1 Mar 2018, 4:41pm

Seems to me that arguing about the extra little bit of weight that disc brakes add to a touring bike is a bit silly. Touring bikes, by their very nature, are heavy. They have to be to support racks and panniers and luggage. The little bit of weight that disc brakes add to the overall is tiny compared to the hefty weight of the bike, racks, panniers, luggage, and rider weight. There's more to be considered on a touring bike and that is simplicity. Dealing with a dodgy disc brake while on tour can ruin your day.

Freddie
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Re: Canti's or V-brakes for new touring frame

Postby Freddie » 1 Mar 2018, 4:50pm

Why not drum brakes? Pads last practically forever and they are completely sealed away, unlike discs. No real need for a beefier fork either.