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Possible new bike, road bike and disks

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  • iPeteiPete Posts: 6,076
    whyamihere wrote:
    iPete wrote:
    whyamihere wrote:
    iPete wrote:
    I've not ridden a disc roadie but I'm pretty sure these comparisons are unfair.

    Try the test again whilst riding on the hoods, not the drops. Throw in some water and stopping on the hoods, even with wet weather pads, is sometimes a very scary experience. With the dics on my mtb I can stop in the wet on the spot using my little finger.
    My tests were all done on the same flat barred bike, in order to eliminate any other variables.

    In that case the difference is probably negligible, if you have to brake suddenly on the hoods in the wet, you have no chance as you can't get the leverage, where I'm fairly sure discs would bite much easier.
    Try better pads. I can just about get my rear wheel to lift braking in the wet from highish speeds on my road bike from the hoods.

    Nick - By woolly I meant less directly measurable.

    Anything that can compete with Salmon Kool Stops for the monies?
  • whyamiherewhyamihere Posts: 7,679
    Salmons are what I use. Swiss Stop Greens are reputed to be good, but cost a fair bit more IIRC.
  • whyamihere wrote:
    Salmons are what I use. Swiss Stop Greens are reputed to be good, but cost a fair bit more IIRC.

    I like a few exoitc fish on the rims i must admit, the pads i use on the disks are sintered, now the disk does wear quicker but for the price of them now and the time it takes to wear the disks your probably onto another bike.

    A bit of a split second in the wet even less then the bite is back, quicker than rims imo. It will be tested when i purchase the CDF, this is experienced on a MTB
  • rolf_frolf_f Posts: 16,015
    iPete wrote:
    I've not ridden a disc roadie but I'm pretty sure these comparisons are unfair.

    Try the test again whilst riding on the hoods, not the drops. Throw in some water and stopping on the hoods, even with wet weather pads, is sometimes a very scary experience. With the dics on my mtb I can stop in the wet on the spot using my little finger.

    Errrm, why would you say the tests I made are unfair? How would you know what I did unless you dug up the threadI made at the time? I went to a lot of trouble dammit :lol:

    I tested a MTB, a new carbon bike with Campag Centaur, a 20 year old Peugeot with STi levers, a Dawes tourer with cantilevers and an ancient Raleigh with Weinmann 605s. The test was made by braking on a downhill gradient after a quarter mile coasting run in dry conditions with approximate pre braking speed recorded (where available). I meant to repeat in the wet but there aren't many opportunities to try (one reason why the advantage of discs in wet weather isn't that significant).

    The older bikes were poorer at braking than the new though by no means terrible. I suspect much of the difference was down to crappier, ancient pads.

    I tested the drop bar bikes on hoods and drops. The Dawes and Raleigh have the old style pivots which are pretty weak on the tops - you can't get the leverage. They were a lot worse. The Carbon Look was better than I thought on the hoods (not much worse than on the drops) but they felt much worse. Perception different to actuality.

    So, broadly speaking, the modern calipers are fine. If riding in the wet, discs are better but don't think that calipers are poor. I have the mtb for bad conditions (snow, ice, blizzard etc) but I don't regard rain as enough justification to take the mtb over the Dawes (which, despite being a poorer braker than the Peugeot or Look, is still perfectly safe for wet conditions as long as you take those conditions into account eg by riding on the drops and moderating speed).

    BTW, first time I braked on the Look in these tests, I just braked as hard as possible and got the back end way off the ground. Braking on the hoods loses the extra braking force you don't need. So the reduced remaining leverage is still enough to stop promptly - hence the feeling that performance is worse when it actually isn't. I was surprised to be honest - I really thought that you'd always be better off braking off the drops.[/url]
    Faster than a tent.......
  • zaneszanes Posts: 563
    Half decent dual pivot calipers with some reasonable pads will lock both wheels (Conti GP4000s on front and rear) on my roadie fairly easily (very easily in the wet), and considering once you're at that stage you're past the point of maximum deceleration I can't see the point of fitting discs, when all they will do is make locking the wheels even easier. Modulation is excellent on the dual pivots.
  • nickelnickel Posts: 476
    Rolf F wrote:
    nation wrote:
    Also, Rolf: your Avids should have self-centring caliper mounts (or at least my old ones did, and my newer Elixirs do). Put the wheel on the bike, slacken the mount bolts by a turn or so, squeeze the lever, and re-tighten the bolts and the caliper whould be perfectly aligned.

    I did actually work that one out - I'm dead clever me! :lol: Trouble is, the damn pads still stick. Sometimes they start to whistle - usually on long slow climbs and the only way to stop it is to briefly apply the brakes. I'd got them running sweetly, then I went away for a week - came back and they were all stuck again - even before getting on the bike!

    I'm tempted to change them for Shimano brakes instead but the Avids do work and they are fine off road. Maybe I just need to bin the Superstar pads which are probably more accurately named Crapperstar. Two pads have completely fallen off the back plate!

    I just replced the pads in my Juicy 3s with some clark's gold kevlar/semi-metallic pads from CRC, 15 quid for two pairs and they were dead easy to fit once i'd pushed the pistons back in (which admittedly on juicys can be a pain in the censored ). Haven't properly bedded in yet so i can't report fully on stopping power, but they already seem on par with the worn avid pads i just replaced.
  • rhextrhext Posts: 1,639
    I think it might be less about "reasons why not" and more about "lack of reasons why".

    When I was a youngster, the rim brakes on my road bike were the bane of my life: never worked in the wet, back wheel never worked at all, cheap steel-rimmed wheels went out of true about 10 minutes after leaving the shop and it was impossible to stop brake-rub thereafter.

    But my modern road bike suffers none of these problems. The wheels stay true pretty much regardless of the abuse they get, modern pad compounds work well in the wet, modern brakes and cables runs/housings are perfectly capable of locking the rear wheel up if you need to. Rim brakes just work, so why bother redesigning frames/forks etc to accommodate disks?

    Combine that with the fact that no-one does hydraulic brake levers for drop-handlebars and it's easy to see why you don't see many full-on road bikes with disk brakes. I'm sure now the UCI has lifted the ban on disk brakes in cyclo-cross we'll see more of them about. But until then I'd not fret too much about having to use rim brakes: they're perfectly fit for purpose if you keep them well maintained.
  • jedsterjedster Posts: 1,717
    To the OP, I'd take a look at the on-one pompetamine - drop bar road bike with lots of mounts, good clearances, cable disc brakes, hub gears. They even do an option with a hub dyno. Checks just about everything on my commuter wish list. Think I'm about to buy one although tempted to wait for the 11 speed shifter...

    BTW I reckon that disc brakes are wothwhile for commuting because:
    a) lower maintenance replacing/adjusting pads
    b) lower rim wear (particularly important if you run a hub dynamo so can't just buy whatever front wheel is going cheap)
    c) better braking in the wet
  • andrewjosephandrewjoseph Posts: 2,165
    if you want disks on a drop handled bike the easiest and cheapest way is road cable disks, avid bb 7's. These will work with STI shifters.

    the other thing to consider is the fork, this will need to able to take disks.

    I have a drop handled tourer with disk brakes, it takes racks and mudguards. The frame does need the drillings and eyelets for a rack.
    --
    Burls Ti Tourer for Tarmac, Saracen aluminium full suss for trails
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