Disc brake upgrade?

whatever13

Hi all, currently commuting on a entry level road bike, with tektro brakes (probably 105 level?) which I upgraded to koolstop salmon pads. It's in pretty good condition but the brakes have never been powerful - I have ultegra on my other bike and they have loads more power in all conditions.

Previously I have stuck to fair weather commuting but lately I have been getting out in all weather. The problem is I am really not happy with the performance of the brakes in the wet, they have always taken a bit of manhandling even in the dry (as you would expect from brakes like these - and that's fine), but when riding in the rain they just seem to give up. A bit of drizzle or a wet road is ok, but when it's properly raining I wrap my hands around the whole lever and pull like hell and still it's a long slow stop. The pads are properly adjusted and I clean the rims and pads as required (can't do much in the middle of a rainstorm!). I'm not locking up the tyres (which are 23c btw).

I ride defensively and take all this into account so I've not had any major incidents but it's the unexpected that bothers me. I don't want to stop riding in the wet as frankly I'd probably never get out in with the weather we've had here lately (Sydney, Australia).

I have the opportunity to upgrade to a cyclocross bike with Avid BB7s for a changeover of probably $500-700 (400-ish GBP) (including fitting some decent 28c tyres) once I sell my bike but I want to make sure that the disc brakes really will make a big difference in proper rain.

My question (after all that) is, for those of you on cable disc brakes (and say 28c+ tyres) how much better than entry level road brakes are they in the wet?

Mr P

I've been trying out a disc-braked road bike and am not going back to rim brakes for winter/wet weather commuting.
I converted a flat bar disc brake road bike (Carrera Gryphon) to drops and BB7s (25mm tyres btw). The modulation isn't as good as hydros (I've since acquired a MTB so can compare) but similar to cheaper dual pivot callipers.
I can now stop in the wet. Every time, without that "am I going to stop in time" brown-trouser delay. The new "problem" is the risk of locking the back wheel though!
I will be looking for a frame that can take wider tyres (I'm at the limit now) when there are a few more drop bar mudguard ready ones on the market. Or I might just spring for a Kinesis Pro6 as soon as the wife isn't looking...
I am doing about 4k miles a year commuting. Was using a Spesh Tricross during the winter, with Tektro CR720 (?) cantis and Koolstops, which was the best set up I found after spending £££ on various cantis, mini-Vs etc. Despite the better spec, it is now relegated and hanging up in the garage in case of emergency; it will be a future donor when I get the new frame.
As you can probably tell, I've been won over. Road-orientated disc brakes can only get better as well now they are CX legal....

PBo

Mr P wrote:

I've been trying out a disc-braked road bike and am not going back to rim brakes for winter/wet weather commuting.
I converted a flat bar disc brake road bike (Carrera Gryphon) to drops and BB7s (25mm tyres btw). The modulation isn't as good as hydros (I've since acquired a MTB so can compare) but similar to cheaper dual pivot callipers.
I can now stop in the wet. Every time, without that "am I going to stop in time" brown-trouser delay. The new "problem" is the risk of locking the back wheel though!
I will be looking for a frame that can take wider tyres (I'm at the limit now) when there are a few more drop bar mudguard ready ones on the market. Or I might just spring for a Kinesis Pro6 as soon as the wife isn't looking...
I am doing about 4k miles a year commuting. Was using a Spesh Tricross during the winter, with Tektro CR720 (?) cantis and Koolstops, which was the best set up I found after spending £££ on various cantis, mini-Vs etc. Despite the better spec, it is now relegated and hanging up in the garage in case of emergency; it will be a future donor when I get the new frame.
As you can probably tell, I've been won over. Road-orientated disc brakes can only get better as well now they are CX legal....

what width tyres do you want? gryphons can take 28s

pdw

I switched to discs for commuting a year ago, and yes, they make a huge difference to the consistency of braking in the wet.

I've got BB7 road calipers + 5600 105 levers, and although it works well I certainly wouldn't call it a perfect setup. The brakes feel very squidgy, and even set with the pads pretty much touching the disc and the cable nice and taught, there's a fair amount of dead travel in the lever before you start to brake, with the lever ending up very close to the bar.

The BB7s do work, and are fairly powerful, but the hyrdaulic discs on my mountain bike, or even the rim brakes on my road bike (in the dry) have a much nicer feel.

More recent STI levers pull more cable, which should address the problem to some extent, but I think that the combination of discs and road levers has a fair way to go.

rolf_f

There are some variables you could check before making an expensive change. For one, disc brakes shouldn't be much better than rim brakes in the dry - I can quite easily put myself over my bars if I use too much brake on my road bikes in the dry. The fact that you state that discs are better in all weathers suggests your current setup is poor.

So if performance is already far short of what it should be in the dry, then no wonder they are scary in the wet; the way you describe your braking is not what you should expect from calipers.

Discs do make a useful difference in the wet but you can mitigate the loss of using calipers by making sure you have the best pads for the job - so the question is, what pads are you using? And what are the brakes?

meanredspider

pdw wrote:

I've got BB7 road calipers + 5600 105 levers, and although it works well I certainly wouldn't call it a perfect setup. The brakes feel very squidgy, and even set with the pads pretty much touching the disc and the cable nice and taught, there's a fair amount of dead travel in the lever before you start to brake, with the lever ending up very close to the bar.
.

OP - See the Boardman CX thread for reviews of discs on CX bikes. I think they are fantastic - infinitely better than regular rim brakes. Unlike pdw, I'm finding BB7 + 5600 105 levers a great combo (and much better than the OEM Apex levers) - makes me wonder if they're set up correctly on pdw's bike.

To put my money where my mouth is, I've just ordered a Volagi Liscio - a full road bike equiped with Ultegra shifters and BB7. For a great video on setting up BB7, search Volagi on YouTube and you'll find their video on setting up these brakes.

As for locking rear wheels, with discs you just need to learn to brake properly which much of the braking effort through the front wheel (except in extremely slipperly conditions). A CX or Road bike is very stiff so the weight transfer under braking means that the front tyre is much more loaded than the rear and can sustain much higher braking forces. For an illustration of something similar, just watch Moto GP where the riders literally have the rear wheels in the air under braking. I think road bike brakes means we get in the habit of hauling on both levers which is entirely unnecessary with discs. In fact, I only upgraded my front brake to BB7 and left the rear as BB5 on the Boardman. On the Volagi, the rear disc/rotor is smaller than the front.

meanredspider

Rolf F wrote:

There are some variables you could check before making an expensive change. For one, disc brakes shouldn't be much better than rim brakes in the dry - I can quite easily put myself over my bars if I use too much brake on my road bikes in the dry. The fact that you state that discs are better in all weathers suggests your current setup is poor.

I'm not sure I buy this. Not only are discs more powerful in all conditions (infinitely so in the wet - despite comparing with Koolstop Salmons etc) even with bog-standard OEM disc pads, but modulation is also much much better. It's similar to race car versus road car brake set-ups - in most road cars you can lock the brakes so people argue what's the point in upgrading? The point is that you can threshold break with far (far) more confidence and repeatedly so. Obviously, the lighter the bike/rider combo, the less braking effort is required and the less advantage disc brakes will give.

rolf_f

meanredspider wrote:

I'm not sure I buy this. Not only are discs more powerful in all conditions (infinitely so in the wet - despite comparing with Koolstop Salmons etc) even with bog-standard OEM disc pads, but modulation is also much much better. It's similar to race car versus road car brake set-ups - in most road cars you can lock the brakes so people argue what's the point in upgrading? The point is that you can threshold break with far (far) more confidence and repeatedly so. Obviously, the lighter the bike/rider combo, the less braking effort is required and the less advantage disc brakes will give.

I actually tested this - I found the dry weather braking on my disc fitted mountain bike, on a steepish descent to be less than 3 metres shorter than the road bike. The limiting factor on the road bike was the going over the bars issue which, with more practice, I may have been able to improve on (the road bike was brand new and I wasn't used to the braking power). The MTB is heavier which here I think is an advantage - ie the weight kept the back down. I should probably repeat the test again now I am more used to the road bike. And I am very light!

I think that for weekend, dry weather country best, there is no advantage in disc brakes at all. For commuting, discs surely do have the advantage but I don't hold with the 'no brainer' mindset. It depends on the nature of the route to some degree (ie if you are likely to need to brake quickly from speed) and the mechanical simplicity of calipers has an advantage (I've never endured a caliper equiped commute with constant squealing and dragging as I have with discs!). For road bikes, I'd be keener to stick with cable discs rather than hydraulics.

What I would say is that I fitted, to my tourer, some rather odd brake blocks at the beginning of the year (the canti brakes are a peculiar design that you bolt through and most blocks won't fit) and I have almost worn them out in 3 weeks despite regularly cleaning the swarf out and recleaning the rims. In contrast, I have just fitted a new caliper set to my MTB and found no sign of any wear on the rotors after 4000 miles. But I do have a nice collection of disc pads with the pad material detached from the backing!

The Rookie

The lad has BB5's on his MTB, they are easily the equal of cheap hydro's (although a little heavier), and the modulation is no worse than on my Juicy 5's on my MTB (must be an avid thing?).

In my opinion, having tried a fair few, the avid BB's are the best cable discs you can buy by a reasonable margin, the only let down is weigh, I use Clarks CMD9's on mine, they are a lot lighter (about 60% of the weight!) but do need a bit of a heave to get them stopping although stoppies are (just) within their/my capability.

Simon

meanredspider

Rolf F wrote:

I think that for weekend, dry weather country best, there is no advantage in disc brakes at all.

This IS the Commuting Forum, though

I think if you are very light, this might explain your point of view. I'm 14+ stone (probably not a million miles from the average middle-aged male commuter weight) and the two sets of brakes are like chalk & cheese to me. I would pretty much guarantee to outbrake (and possibly by some margin) someone of a similar weight using road brakes of a broadly similar pricepoint (I don't have experience of some of these Uber-expensive systems) in the dry. In the wet, road brakes are like bringing a knife to gunfight. I am soooo much more confident to brake late in all conditions.

Holding 2 rubber blocks against the outside of the wheel is 19th century technology. I'm confident that in 10-15 years time, pretty much every bike sold will be on discs. The pros don't use it because it's banned (because?). The weight isn't an issue as most pro road bikes come in under the limit in stock form. It adds about 350g in total to an average (105 equiped) road bike. Heat generation (not to mention wear) in carbon road rims is an issue on long descents. But damp, crappy, roads (as us commuters often face) is where the big advantage is.

bails87

I think that when the braking surface is dry it's almost as easy to reach the limit of tyre grip on rim brakes as it is with discs. If I wanted to, I could pull a stoppie on my Ribble with 105 calipers. I could do the same on my Boardman with BB5s. That's as much braking force as I need, any more and I'll go over the bars and probably be worse off than just hitting whatever it is I'm trying to stop for! On a damp road (with dry rims) I could easily lock up the front with either, again, that's as much braking power as I need, slightly more than is safe actually. I do only weigh 65kgs/10andabit stone though.

But in the wet, rim brakes deteriorate dramatically. Disc brakes keep working pretty much the same. That's where they're well worth it. They saved me from putting a hole in the side of a Bentley that pulled out in front of me at the end of last year!

Hydraulic road systems would (will?) be very interesting, as the hydros on my MTB have better feel, more power and need less maintenance/adjustment than the BB5s.

rolf_f

meanredspider wrote:

I'm confident that in 10-15 years time, pretty much every bike sold will be on discs.

I do really hope you are wrong. Technology is great if you need it but terrible if you don't. For weekend work, rim brakes are something that don't need fixing.

As to 19th century technology - what do you think a bicycle is?

bails87

Rolf F wrote:

meanredspider wrote:

I'm confident that in 10-15 years time, pretty much every bike sold will be on discs.

I do really hope you are wrong. Technology is great if you need it but terrible if you don't. For weekend work, rim brakes are something that don't need fixing.

As to 19th century technology - what do you think a road bicycle is?

FTFY




"19th century"....really :roll:

meanredspider

Rolf F wrote:

As to 19th century technology - what do you think a bicycle is?

Even on a road bike...

Di2
Carbon Fibre
Titanium
Aero parts
Ceramic bearings

and, err, rubber or cork blocks...... :roll:

meanredspider

bails87 wrote:

I think that when the braking surface is dry it's almost as easy to reach the limit of tyre grip on rim brakes as it is with discs. If I wanted to, I could pull a stoppie on my Ribble with 105 calipers. I could do the same on my Boardman with BB5s. That's as much braking force as I need, any more and I'll go over the bars and probably be worse off than just hitting whatever it is I'm trying to stop for! On a damp road (with dry rims) I could easily lock up the front with either, again, that's as much braking power as I need, slightly more than is safe actually. I do only weigh 65kgs/10andabit stone though.

But in the wet, rim brakes deteriorate dramatically. Disc brakes keep working pretty much the same. That's where they're well worth it. They saved me from putting a hole in the side of a Bentley that pulled out in front of me at the end of last year!

Hydraulic road systems would (will?) be very interesting, as the hydros on my MTB have better feel, more power and need less maintenance/adjustment than the BB5s.

As per my point above, though, it's not ultimate braking force but modulation (I've been through this debate loads of times on car forums). I could (theoretically, at least) lock my wheel by poking a stick through the spokes. The most effective braking in (almost) any condition (snow might be an exception) is threshold braking as tyres give up the most grip with a small amount of slippage. Getting to that (or close to it) consistently and predictably is where discs have a big advantage. That, heat dissapation and wet weather performance. Oh, and for us men built like men

pdw

Unlike pdw, I'm finding BB7 + 5600 105 levers a great combo (and much better than the OEM Apex levers) - makes me wonder if they're set up correctly on pdw's bike.

I did spend a long time trying to improve it when I first fitted them, including changing the outers to supposedely compressionless ones, making sure that all the joins were perfectly square, and following every bit of advice on the interweb from the plentiful supply of other people who have encountered similar problems.

I got it as good as I could and decided to live with the fact that they were "good enough" and that they were never going to be really good. The calipers really need to move the pads more at the beginning of the stroke, so that you can the pads a little further away from the disc, yet still make contact quickly.

It may be a question of expectations and preferences: I hate squidgy brakes, and am used to a very firm set up on my other bikes. I'm looking forward to better road disc options coming on the market, as experience of MTB brakes tells me that they can be much better. As it stands, BB7s are best of a pretty average bunch. They're heavy and the design hasn't really changed in years. I put that down to a lack of competition and market, rather than the fact that the design can't be improved.

meanredspider

A BB5 caliper is a shade under 250g (with pads) and a 105 caliper is a shade over 200g with pads - that's less than 50g difference. I'm sure road disc-specific wheels could be made close to 100g lighter with no brake wear surfaces to offset the weight of a disc so, honestly, the weight thing is a bit of a red herring - never more so than on a commuting bike often fitted with puncture-resistant tyres, mudguards, lights, panniers(?) etc etc

You needs some lever travel to modulate the brakes else it's a switch. Whether you call that squidgy, I don't know. The caliper lever should move the pads instantly as there should be some pre-load in the caliper lever (ie it shouldn't be sitting on the stop but part-way around the stroke). The only other challenge then is the run-out of your disc which is the only thing that determines the need for pad travel. Given that the brakes need less force to operate than road calipers, elastic stretch of the brake cables (and compression of the outers) should actually be less.

pdw

meanredspider wrote:

A BB5 caliper is a shade under 250g (with pads) and a 105 caliper is a shade over 200g with pads - that's less than 50g difference. I'm sure road disc-specific wheels could be made close to 100g lighter with no brake wear surfaces to offset the weight of a disc so, honestly, the weight thing is a bit of a red herring - never more so than on a commuting bike often fitted with puncture-resistant tyres, mudguards, lights, panniers(?) etc etc

Interesting. When I felt the thing in my hand, I have to say it felt pretty damn heavy compare to the 105 caliper, but I didn't measure it. And yes, my commuting bike is bogged down with lights, mudguards, panniers and racks. That doesn't mean I don't want to save weight where possible.

You needs some lever travel to modulate the brakes else it's a switch.

Actually you don't. It's quite possible to exert different amounts of force on something without it moving at all.
Once the pads are in full contact with the disc, the amount of friction just depends on the amount of force on them. They don't need to move, and the disc isn't really going to compress...

To be able to modulate, you just need the friction force to increase predictably with the force applied at the lever, and for the brakes to not be so powerful that you struggle to apply sufficiently little force. Lever travel is irrelevant.

Whether you call that squidgy, I don't know.

Compared to my mountain bike, even once the pads are in contact with the disk, the lever moves further for a given force. I call that squidgy.

The caliper lever should move the pads instantly as there should be some pre-load in the caliper lever (ie it shouldn't be sitting on the stop but part-way around the stroke).

It does - the cable is nice and taught. But as I said, even with the pads screwed in so that they are just pretty much touching the disc, I have to move the lever a fair way before they are properly engaged with the disc.

The only other challenge then is the run-out of your disc which is the only thing that determines the need for pad travel.

There is some run-out, but it's pretty small - certainly no more than on other discs.

Given that the brakes need less force to operate than road calipers, elastic stretch of the brake cables (and compression of the outers) should actually be less.

I find the forces pretty comparable, in the dry. Bear in mind that the greater mechanical advantage of the calipers is offset by the much small diameter of discs compared to rims. Disc brakes also require longer cable runs, particularly at the front, and the in-line adjusters used on Avid brakes require two extra joins, all of which contribute to the compressibility of the outers.

The Rookie

Magura used to do hydro drop levers for their rim brakes (I've seen some), wonder if you could fit a magura calliper to them? Are they the same 'ratio'?

Simon

meanredspider

I'm not going to do a "several level" quote, but a few key points:

- I'm sure there are far more effective places of finding 100g on a commuter than the brakes - especially when you get left-hooked in the wet.

- Fluids in hydraulic brakes are incompressible. Any compression is "give" in the walls of the tubing. Cables, on the other hand, stretch elastically (and the outers compress). To achieve the modulation in force, you have to have varying stretch which leads to movement in the lever. It's the same for road calipers except, IMO, the forces applied need to be higher which leads to more stretch.

- If rim brakes were as effective as disc brakes, MTB brakes (that use the same Avid rotors) would only be as effective as rim brakes. Yet MTB brakes are clearly (again, IMO) far more powerful and yet operated by 1 finger (mechanical advantage cancelling out at either end)

- I have absolutely no in-line adjusters - what's the point in them (two?)? Each pad is individually adjustable by hand. Wind each one in until they lock the disc then back off about 3 clicks to achieve free rotation. Adjust once a month as necessary. If you are CXing or MTBing in mud, I can imagine an adjuster to take up extreme pad wear mid-race without fiddling about in a cacked-up caliper, would be useful. Not so on a commuter/roadie.

pdw

meanredspider wrote:

- I'm sure there are far more effective places of finding 100g on a commuter than the brakes - especially when you get left-hooked in the wet.

I'm not arguing - I have discs on my commuter. Doesn't mean I wouldn't prefer them to be lighter.

- Fluids in hydraulic brakes are incompressible. Any compression is "give" in the walls of the tubing. Cables, on the other hand, stretch elastically (and the outers compress). To achieve the modulation in force, you have to have varying stretch which leads to movement in the lever. It's the same for road calipers except, IMO, the forces applied need to be higher which leads to more stretch.

In my experience the loads are similar, but the cable runs are longer and you have more joins, leading to similar amounts of compression in normal use. I agree that in practice there will be some lever travel as you vary the force, but you don't need lever travel in order to be able to modulate the brakes.

- If rim brakes were as effective as disc brakes, MTB brakes (that use the same Avid rotors) would only be as effective as rim brakes. Yet MTB brakes are clearly (again, IMO) far more powerful and yet operated by 1 finger (mechanical advantage cancelling out at either end)

The advantage of discs on MTBs isn't just about the power, it's about what they do when they're covered in mud. MTB discs are typically bigger than the Avid road discs, and that does lead to more power. 1 fingered braking works because you put your strongest finger furthest from the pivot on the lever. You don't need particularly powerful brakes to do it effectively.

- I have absolutely no in-line adjusters - what's the point in them (two?)? Each pad is individually adjustable by hand. Wind each one in until they lock the disc then back off about 3 clicks to achieve free rotation. Adjust once a month as necessary. If you are CXing or MTBing in mud, I can imagine an adjuster to take up extreme pad wear mid-race without fiddling about in a cacked-up caliper, would be useful. Not so on a commuter/roadie.

The inline adjusters aren't to compensate for pad wear (the instructions are pretty clear on this). They're to make it easy to get the caliper set up right, so that you can get the cable taught, but without losing any travel in the arm. I'm you could get them set up adequately without them, and that would remove some of the compressibility.

meanredspider

pdw wrote:

The advantage of discs on MTBs isn't just about the power, it's about what they do when they're covered in mud. MTB discs are typically bigger than the Avid road discs, and that does lead to more power. 1 fingered braking works because you put your strongest finger furthest from the pivot on the lever. You don't need particularly powerful brakes to do it effectively.

The inline adjusters aren't to compensate for pad wear (the instructions are pretty clear on this). They're to make it easy to get the caliper set up right, so that you can get the cable taught, but without losing any travel in the arm. I'm you could get them set up adequately without them, and that would remove some of the compressibility.

Just got home on the CX after having ridden the Focus (road brake equipped bike) yesterday. There is absolutely no way on earth that the road brakes are as good as the discs. If I can be bothered over the weekend, I'll strap my accelerometer that I use in my race car to both bikes and actually measure the difference in braking performance.

MTB disc brakes (as I discovered on the Puffer) are at their worst covered in mud - they wear out in no time - even the sintered pads. The key point is that they are less likely to get covered in mud where they are. They do work better in the wet though (just like the Avids).

If that's what the adjusters are for, they are a total waste of time. I have a solid run of outer from the lever to the caliper. Again, reviewed the performance of my lever on the way home tonight - would want it any different. Any less "lost travel" in the lever and I'd find I was applying the brake as I shifted.

rolf_f

meanredspider wrote:

Rolf F wrote:

As to 19th century technology - what do you think a bicycle is?

Even on a road bike...

Di2
Carbon Fibre
Titanium
Aero parts
Ceramic bearings

and, err, rubber or cork blocks...... :roll:

Di2 is a nice frippery that enables people who can't index have an easier life.
Carbon fibre is just a material that reduces the weight of the bike but it doesn't alter the 19th century functionality in any way.
Ditto titanium
Sorry - I don't have any bits of aeroplanes in my bikes! As for aerodynamics - not really of any benefit at all to 99.9999% of us. So those of us who do buy it are mainly doing it for the aesthetics - which isn't exactly a new motive.
Ceramic bearings - as per Di2. Infact, TBH, there is really no point in ceramic bearings other than bragging rights. And ball races have been around for a very long time.

OK, to be fair, the bikes we ride today are really mostly mid 20th century technology in detail. But don't make out that discs are a bigger deal than they are. All they really do is allow you to go safely, a bit faster, in the wet. You can achieve the same result by slowing down a bit. They are a nice thing to have if you want them - and no more. As far as I can see, the last significant development for the road bike was the parallelogram derailleur. Nothing much has changed since. Yes, lots of little improvements but nothing of earth shattering importance.

Different for MTBs - effective suspension and frame design has I think made significant steps forward there.

And of course it is mad to suggest that something is obsolete because it is 19th century (or earlier) technology - or are you claiming the wheel as 21st century technology

pdw

Just got home on the CX after having ridden the Focus (road brake equipped bike) yesterday. There is absolutely no way on earth that the road brakes are as good as the discs. If I can be bothered over the weekend, I'll strap my accelerometer that I use in my race car to both bikes and actually measure the difference in braking performance.

MTB disc brakes (as I discovered on the Puffer) are at their worst covered in mud - they wear out in no time - even the sintered pads. The key point is that they are less likely to get covered in mud where they are. They do work better in the wet though (just like the Avids).

If that's what the adjusters are for, they are a total waste of time. I have a solid run of outer from the lever to the caliper. Again, reviewed the performance of my lever on the way home tonight - would want it any different. Any less "lost travel" in the lever and I'd find I was applying the brake as I shifted.

I'm not sure what the accelerometer is going to tell us. Assuming you have enough power in the front brake on both bikes to lift the back wheel, then all it's going to tell us is the angle between the front contact patch and the centre of gravity. If you don't have that much power on your road bike, then that might explain things...

Sure MTB brakes eat pads in the mud, but at least they still work.

meanredspider

Rolf F wrote:

Sorry - I don't have any bits of aeroplanes in my bikes! As for aerodynamics - not really of any benefit at all to 99.9999% of us. So those of us who do buy it are mainly doing it for the aesthetics - which isn't exactly a new motive.
Ceramic bearings - as per Di2. Infact, TBH, there is really no point in ceramic bearings other than bragging rights. And ball races have been around for a very long time.
:

Of course aerodynamics affect us. Don't have the exact numbers but, at 20mph, 80% of our effort goes into moving the air. Tight Lycra, drop bars, aero wheels to name just a few.

The point about all the other things is that we've significantly advanced the technology. There's hints of Luddite in your response - Electronic shifting, for instance, will just be the way it's done in the future. I'm guessing it will jump to wireless at some point but it's just the way things move (if you've ever done TRIZ, you'll know that's the way things move in general - typing this on my new fangle electronic wireless typewriter....). Just about every other vehicle braking system is disc brakes. Or are you arguing that the car is still just a horseless carriage and the modern jetliner owes everything to the Wright brothers? The concept's the same, the technology has moved on. Time road bike brakes did. and they will.

meanredspider

pdw wrote:

I'm not sure what the accelerometer is going to tell us. Assuming you have enough power in the front brake on both bikes to lift the back wheel, then all it's going to tell us is the angle between the front contact patch and the centre of gravity. If you don't have that much power on your road bike, then that might explain things...

Sure MTB brakes eat pads in the mud, but at least they still work.

And that's exactly it! There's not enough power in my road brakes to lift a rear wheel with 14st of me on the bike. That's comparing 105/KoolStop set up with Avid BB7/OEM pads - both mid-range braking systems. Huge difference in performance.

whatever13

Thanks for the responses all.

I'm sure my current brakes are pretty rubbish as rim brakes go. They are a few years old Tektro 720s (specced on a 105 level groupset) to which I have fitted koolstop salmon pads. I have them adjusted pretty well and sanded them back, cleaned rims and in the dry they are still dramatically less powerful than the Ultegras with stock pads on my good roadie.

So before it starts raining I'm already at a disadvantage. But upgrading to ultegra would cost more than the new bike changeover and I'd still get a drop off in performance in the wet.

So your views are all really helpful and it sounds like discs would be a very worthy upgrade for me. Sadly with all this faffing I've missed the deal I was chasing! So I'll be waiting a bit longer.

Out of interest you should have seen how bad they were before the koolstops! The pads literally dissolved in the wet, losing mms of thickness in a single ride and smearing sludge everywhere - so bad ... and fairly terrifying the first time I encountered that situation.

meanredspider

Yup - sorry for the long diversion into the pros and cons of discs. I'm a modernist when it comes to bikes but I recognise the road bike world, in particular, is full of conservatives and slow to adopt new technology. The MTB world, possibly because the whole arena is relatively new, is much quicker to adapt and modernise.

I know what you mean about the differing capabilities of the road brake set-ups. A 60kg colleague broke his £5k Madone so borrowed a friend's Tiagra equipped Trek for a ride with me. At a T-junction after a long downhill drag, he said he was considering using me on my stationary bike as a brake because he didn't think the brakes were going to stop him in time. That was in the dry! I'm sure if you weigh nothing, with a bike that has the latest & best brakes, rim brakes will do the job some of the time.

supersonic

The rim brakes on my Zaskar LE (Avid Arch Rival, Speed Dial 7 levers, Kool Stop Eagle) on CrossMax Enduro rims are easily as good as any hydro I have tried, at least in the dry. I weigh 14st kitted out. I can adjust bite point easily, and leverage, something you can't always do with hydraulic disc brakes. The limiting factor is tyre grip.

It really does depend on model and set up. Some disc brakes are awful, some rim brakes amazing. But it will be a sad day if we see rim brakes go, as to many they are simple, effective, cheap and easy to service. I don't need discs on that bike, and if my other bikes had mounts, I'd probably go for V brakes on them too.

People tend to associate modulation with lever throw coupled with increasing lever resistance. And of course we all like different feels, some really do like blunt 'on/off' power.

rolf_f

meanredspider wrote:

Of course aerodynamics affect us. Don't have the exact numbers but, at 20mph, 80% of our effort goes into moving the air. Tight Lycra, drop bars, aero wheels to name just a few.

The point about all the other things is that we've significantly advanced the technology. There's hints of Luddite in your response - Electronic shifting, for instance, will just be the way it's done in the future. I'm guessing it will jump to wireless at some point but it's just the way things move (if you've ever done TRIZ, you'll know that's the way things move in general - typing this on my new fangle electronic wireless typewriter....). Just about every other vehicle braking system is disc brakes. Or are you arguing that the car is still just a horseless carriage and the modern jetliner owes everything to the Wright brothers? The concept's the same, the technology has moved on. Time road bike brakes did. and they will.

I assumed you meant aero on frames since that was what we are talking about. Drop bars - not exactly 21st century. Aero wheels - largely irrelvant for most of us (again, primarily about bling when low profile, light weight would suit most better). Lycra is not part of my bicycle.

No, I'm not a luddite - I just react against the mindless assumption that because something is new, it is better. It is not. Analogising cycle discs to car discs isn't really that clever - a car is a different thing to a bicycle or do you run your bicycles with thick treaded tyres because cars do? As for electronic shifting - so far, the only convincing argument I've heard in its favour is that it improves the front shift. So, arguably, an electric front shift with much lighter batteries and cable rear would be the optimum but you never hear that suggestion. Either way, you haven't come up with anything to convince me why adding extra weight to my bike would improve it.

For me, the beauty of a bike is its mechanical simplicity - I don't want to turn it into another piece of electro-tat that goes obsolete after six months. I have enough things with batteries in them already - my bike won't be another one.

You are actually making some pretty stupid comments here (eg horseless carriages, Wright brothers) which aren't helping your more constructive arguments. I think it is fine that you want discs and Di2 but you are fooling yourself if you think that there are some fantastic revolutionary step forward. They are not. They have their place (particualary in the mid end market) but they are significant negatives along with the advantages. There is an optimum point to development beyond which things degenerate.

I think you perhaps are a bit too keen to believe the industry hype (the industry whose role is not to provide us with the perfect bike but to sell us new stuff). But your new bike is very pretty (despite the discs!)

rolf_f

supersonic wrote:

The rim brakes on my Zaskar LE (Avid Arch Rival, Speed Dial 7 levers, Kool Stop Eagle) on CrossMax Enduro rims are easily as good as any hydro I have tried, at least in the dry. I weigh 14st kitted out. I can adjust bite point easily, and leverage, something you can't always do with hydraulic disc brakes. The limiting factor is tyre grip.

I checked up my brake test - on a fairly decent slope, braking from 22mph, my heavy Orange P7 with hydro discs took just under 9m to stop. My Look, with Campag Centaur, took 10.5 m to stop.

Even the 30 year old, bendy Weinmann calipers fitted with rock hard, 30 year old blocks on chrome rims on my ancient Raleigh only took another couple of metres to stop - I wish I could retest it now it has new blocks and alloy rims.

So 1.5 m difference with the limiting factor not the stopping power of the brakes but the lack of weight of the Look meaning any firmer on the brakes and I'd have been over the bars whatever braking system I used. So, with the discs being a heavier setup and more complicated to run and maintain, the rim brakes win easily. For a weekend bike.