Carbon fibre disk brake touring fork

[belgiangoth]

I have wheels with different rim widths (alesa endeavour and open pro). As I run fixed gear, I could just figure that I can swap forks on n+1 just as well as on my current bike.

Surprised you still rate hub brakes. For 622s I think their stopping distance is too long, also not sure they have good hub dynamo options (and deco no fixed gear option).

[robc02]

Surprised you still rate hub brakes. For 622s I think their stopping distance is too long, also not sure they have good hub dynamo options (and deco no fixed gear option).

As far as braking power is concerned I would find SA 70mm drums fine for most commuting - indeed I completed Lon Las Cymru, with camping gear, on a drum braked bike with no problems. In standard form they don't have the absolute stopping power of discs, but they are plenty good enough and generally more robust. I have modified one to have a floating cam (there is a thread on here somewhere) and it will lock the back wheel when progressively applied (as opposed to jamming it on) - I think it would be too sharp for the front.

I gather that when new they take a while to bed in, so may feel weak for a while.

SA make a front drum with dynamo, but it is quite a heavy unit.

SA also make a rear hub for a threaded cog or freewheel, so singlespeed is possible. It doesn't have a left hand thread for a lockring though. Having said that I never used a lockring for fixed, and never had one unscrew after it had been initially tightened - so it wouldn't bother me, but others may think differently.

[Brucey]

....Surprised you still rate hub brakes. For 622s I think their stopping distance is too long, also not sure they have good hub dynamo options (and deco no fixed gear option).

Well, I suspect you have never tried a good set of hub brakes that were set up right. Last time I checked my 70mm hub brakes (on 590s with 37s fitted, so maybe 4% better than 622s...?) will stop me dead from about 20mph in about 4m on a dry road. On a wet road you need to be careful, just as with any reasonably powerful brake. I'm not going to do stoppies on these particular brakes but I don't think they need to be any more powerful than they are. The brakes normally work quietly and (with a few exceptions) work the same in any weather; although in ideal conditions a disc brake might modulate better than a drum, given a choice between discs and drums I'd say drums -on average- behave more consistently overall.

Where I am, they need adjusting maybe twice a year when they are bedding in and less often than that subsequently. It might be more than that in very hilly territory but it is hardly a chore and is better than with cable-operated discs. Bearings are super-smooth and if they ever fail they are pennies to replace. By accident or design these hubs (in non generator form) have a very small airspace inside and this means the weather isn't sucked into the workings by temperature changes.

If you want to run singlespeed then an X-RD hub can be used (although perhaps not at 135mm with every chainline, because the axle is shouldered and can't be moved sideways). Having happily ridden tens of thousands of miles on fixed without a lockring I don't think you need one for the road, not if you have two brakes. If this still worries you, use threadlock on the sprocket.

If you want a hub generator then you can have one, 2.4W or 3W. These generators are not the best in that they drag about the same whether the lights are on or off. If this or the weight bothers you, I'd suggest a spare wheel with and without the hub generator fitted; a spare wheel is handy anyway and you need only bear the weight and the drag (such as it is, about 1/4 the drag of single decent tyre) when you need the lights in the wintertime. The smart choice is probably the 2.4W generator; it has enough power for most uses and drags a bit less than the 3W model. It might be a touch lighter, too.

Weaknesses are

- the flanges are a bit soft; I've seen a few distorted spoke holes (from prangs) and one flange failure. [Although often the soft flanges more easily build into a better wheel because they support the spoke better.]
- to get the best out of these brakes they need to be a) bedded in properly (and this might take over a year of normal use...) and b) a semi-floating brake plate conversion helps too; this speeds the bedding in process and provided more consistent power over the life of the brake shoes.
- the wheels are slightly more fiddly to remove. I guess the front is a little worse than a disc brake (you need to guide the reaction arm into its slot, which is comparable to getting the disc in the caliper slot, then hook the cable up - snap fit by hand- and tighten the track nuts) and the rear normally has a bolted reaction arm. You can convert the rear to a slotted reaction arm mounting if needs be.
- they are heavier than V brakes for sure (but are only about 1/2lb heavier than many disc brake setups, and because of the way the load is transferred into the fork, you can often still use a relatively lightweight fork so you may get the weight back that way at the front)

For commuting, bike racks etc drum brakes are pretty faithful devices and (unlike discs) are not easily wrecked when the bike is parked. Your bike won't be so likely to get nicked, either.

So yeah, for commuting I think they have a lot going for them, drums do.

cheers

[robc02]

Link to a thread on improving drum brakes:

http://forum.ctc.org.uk/viewtopic.php?f=5&t=68691&hilit=floating+cam+drum

Includes contributions from Dave Wrath-Sharman, designer of the Highpath "Swing Cam". My own floating cam mod is on page 2.

Also interesting:

http://www.63xc.com/dws/hubbrake.htm

Drum brakes: under rated, unfashionable....apart from that, fine!

[james-o]

Disc brakes have their plusses and minuses, but for most of the winter there is no real benefit in terms of braking performance because that is limited by the grip of the tyre on the (wet, muddy, icy) road anyway.

For someone with your technical experience I'm suprised to read that. That point has been discussed many times elsewhere. Using good discs shows that it's all about how much feel or modulation you have up to that limit of traction - the gain is in control rather than ultimate stopping power that as you say is limited by grip.

[Brucey]

OK perhaps I should have been clearer, you are right a better modulating brake can be better, if you are able to know how grippy the surface is (or feel it) and likewise know how the brake will behave (or feel it).

These things are more or less accessible and valuable when (say) MTBing, because the brakes are constantly in use and the tyres are moving around a lot nearly all the time. But when commuting neither of these things is true in the same way; more example I found that the same brakes (hydraulic discs) that were magnificent when MTBing were almost useless when commuting.

I'd be riding along for a considerable length of time without using the brakes and when I needed them if the brakes were at all wet they wouldn't have any immediate bite (worse than a lot of rim brakes in fact), which made them worse than useless if someone stepped off the pavement in front of me. If the brakes were dry they would have enough power to lock either wheel at will when the surface was wet/greasy, so it was a guessing game if there was enough grip to allow use of much of this power or not.

Now had they been cable discs I'd have been happier about fitting sintered pads (which would have been better, not perfect) and had the weight distribution been different maybe a front wheel lock-up wouldn't have been such a danger. But at worst the performance of the brakes changed radically depending on the exact amount of diesel in the last puddle I went through and when the brakes were working properly I was only ever about half a second away from throwing myself off the bike; not exactly ideal when you are feeling tired and just want to get home in one piece.

Shimano clearly feel that there is an issue here too; their 'commuting brake' (the roller brake) comes fitted with a clutch in the front hub whose sole purpose is to stop you from throwing yourself over the handlebars if the brakes work 'too well'. I've seen as many nasty accidents through brakes working 'too well' than ones that didn't work well enough.

Having ridden extensively on a lot of different brakes I have come to the conclusion that whilst -at best- disc brakes can modulate very well, they are overall not as consistent in their behaviour as good drums are, not in an all-weather commuting context.

No-one (no one with any brains) is routinely trying for that last few percent of braking power/modulation when they are riding home on a dark wet Friday night; no, for planned braking etc everyone rides well within the (known or supposed) limits of their brakes or tyres whatever they might be. It is the unplanned braking and manoeuvring that is more of a worry.

When commuting the thing that can save a nasty accident is that you can grab an handful of brake in a hurry and know that something consistent and moderately powerful will happen. It is no accident that (say) modern car brakes are so much more powerful than older ones used to be; most drivers don't have the skill to exploit these powerful brakes without the ABS even under normal conditions and when in a panic situation (emergency stop) they certainly don't.

Bike brakes don't have ABS and panicy riders are no better than panicy drivers are; in an emergency if the system -unpredictably- either does very little or alternatively throws you off the bike it is not a good system for this use, no matter how good it might feel the rest of the time.

cheers

[Phileas]

From my own experience as a fast commuter on a road bike (20+ years), I find mechanical disc brakes (with sintered pads) much better than dual pivot rim brakes in the wet. I haven't yet (after one year) found my braking limited by road grip.

Perhaps I've been lucky?

The only problem I've had, and I'm trying to sort it out this weekend, is awful squeal (under certain conditions) after fitting new pads for the second time (different make). Apparently I was supposed to bed them in but it doesn't mention this on the instructions.

[james-o]

I'd agree with a lot of that Brucey. Commuting on salty or oily roads can make a joke of a disc pad pretty fast, the main con vs the generally weaker but predictably so performance of rim brakes in the wet. I've never found discs an issue with upsetting my balance on the bike, the power's there but the control makes it pretty hard to go OTB anything but a very steep off-road situation.

As for a carbon touring fork though, I'd not bother. I think the scare stories of carbon can be overplayed but still, steel just works so well.

[Brucey]

From my own experience as a fast commuter on a road bike (20+ years), I find mechanical disc brakes (with sintered pads) much better than dual pivot rim brakes in the wet. I haven't yet (after one year) found my braking limited by road grip.

Perhaps I've been lucky?

maybe; but then again the weight distribution has a lot to do with it too. If the bike is front endy enough, the surface needs to be super slick before you are going to lock the front.

The only problem I've had, and I'm trying to sort it out this weekend, is awful squeal (under certain conditions) after fitting new pads for the second time (different make). Apparently I was supposed to bed them in but it doesn't mention this on the instructions.

there are a few things that are worth trying here but nothing is guaranteed to work. A little copper-ease on the pad backings can sometimes work wonders, as can filing a lead-in on the pads, using different discs (it is often the discs that 'sing'). FWIW if I had to choose discs for commuting I'd choose mechanical discs with sintered pads but they are not perfect (is anything....?... ).

cheers

[Phileas]

Well I sanded the rotor a bit (front - I don't use the rear at all) and the pads slightly. Went for a ride and did a few hard brakings in the dry as per recommendations - no squeal but then there wasn't really before in the dry.

On the way back it was raining and there was some squeal initially but not as bad as before. I'll see how things go this week.

[Stevek76]

I've been commuting on cable discs for some years and found shimanos resin pads to be good both wet and dry. Good grab and surprisingly resilient to fade as well, certainly never had any noticeable reduction in power when needing to stop after riding the brakes down the hills round here. The negative is that they don't last all that long. I've tried a few sintered pads but generally found them to have worse initial grab and lower overall power and a slightly 'woolly' feel, they do last though.

On the flip side the avid organic pads that come with the bb7 road sl are pretty poor ime. Initial grab is decent in the dry, ok in the wet, but they fade really badly. They did last ages though. Tried out some ashima mixed compound sos ones more recently and they are much better.

I haven't yet (after one year) found my braking limited by road grip.

In 'normal' wet conditions I've found that to be the case as well. If it's the first rain for ages (so the roads are particularly oily), or leaves, ice, manhole covers etc then obviously it's a different matter. Even so, ever since I took a particularly nasty trip ohb when I first restarted cycling several years ago I tend to do practice emergency stops on a fairly regular basis so I know what I'm doing when the real thing is needed. I have found that a good set of low friction compressionless cables helps a great deal with the overall feel and power.

I'd considered hubs when building my current commuter/city get about bike but given my loaded weight is close to the 100kg limit and the hills round here it didn't seem a great idea, not keen on the power modulator either.

[willcee]

Interesting contris, ''upgraditis'' is an affliction seemingly more prevalent amongst the young and relatively inexperienced..I happen on it from time to time in my own life working amongst bikes... Brucey and other more experienced forum users on here have amassed many many years of knowing what actually works and is an actual benefit to ones cycling.. its called experience and comes with age.. that allied with common sense, which in these '' enlightened'' days doesn't seem to be that common at all..''upgraditis'' I call it reinventing the wheel..