Looks like we're getting there:
[url= http://www.bikeradar.com/gear/category/components/groupset/road/product/review-sram-red-22-with-hydro-r-disc-calipers-47179 ]SRAM red group with disc brakes[/url]
Interestingly I read that the design of carbon road rims is being held back by the need to use heat resistant resins in the manufacturing process. The resins they use are inferior (in some way) and so carbon road wheels don't perform as well as they might otherwise.
Freeing up the rim design from having to also accommodate a brake track (two gains one in reduced weight and the other in more consistent braking performance) should be a big step forward but I have also read that the greater problem for disc brakes to overcome is their poor aerodynamic performance.
All interesting stuff.
We've been there for decades - what has happened is that the regulations have changed so manufacturers are putting a bit of work into it.
The UCI - making bikes slower and more dangerous since 1934.
geetee1972 - Member
...the greater problem for disc brakes to overcome is their poor aerodynamic performance...
A lightweight drum brake would fix that.
Unfortunately such a creature does not exist - I've been looking for a long time.
Interesting re. resins. A problem for carbon rims is the moulding process for clinchers - tub rims are lighter.
As for deep section ones, are any carbon rims made with the aero section being non structural? One would think that would save a lot of weight.
I still hanker after a set of PX 20mm rims on ebay hubs, 1200gm for £300 odd IIRC.
I think you need to try the search function
* Thread closed * 🙂
Fugly discs on Roadies are, just fugly.
Can't see the benefit/need/point of them on Roadies, MTBs though, different thing altogether.
FWIW, I'm pretty sure on this discussion about rims that one of the carbon wheel companies said that they didn't expect discs to lead to significantly lighter wheels in themselves because the rims are currently limited by their structural requirements (eg that they don't break when hitting bumps in the road, etc) rather than the need for a braking surface.
The UCI - making bikes slower and more dangerous since 1934.
And potentially more so if hydraulic road discs can't cope with heat. Although there have been heat issues with rim brakes too.
When I saw the SRAM Red stuff, I assumed it was aimed at Cyclocross, where disc can make sense and has been allowed by UCI, rather than road use.
And potentially more so if hydraulic road discs can't cope with heat
The article suggested that the new version from SRAM didn't present any problems to their 190lb riders but interestingly SRAM have placed a 250lb rider + bike limit on the system presumably for this very reason.
Clubber I am aware of the other disc brakes on road bike threads hence I thought this article would be of interest.
And potentially more so if hydraulic road discs can't cope with heat. Although there have been heat issues with rim brakes too.
They've only been having heat problems because they've been trying to make ultralight rotors and someone forgot basic thermodynamics 😉
Discs have been used on much faster bikes for years - lots of recumbents use discs without any problems.
I don't like the SRAM double-tap system so I'm waiting to see what Shimano do then I'm going to build myself the closest thing possible to a lightweight crossover winter trainer based on a CX frame with mostly road components, discs and the ability to take mudguards and a rack. I bet it won't be long before the big manufacturers follow my design brilliance with yet more niche bikes.
250lb is not a huge amount. Not sure how much margin that includes, but I'm not exactly massively overweight, and would be right on the limit.
Might be handy for criterium type races too. Don't expect to see it on alpine stages of TdF for a while yet.
[i]250lb is not a huge amount[/i]
Nearly 18 stone is [i]quite[/i] a lot, isn't it?
Given the type of buyer most high end road kit gets I'd say it wasn't an unreasonable figure.
I'd be checking frame and wheel weight limits too if I was spending for posh stuff and weighed that much.
Yeah 250lbs, taking off a 20lb road bike and 8lbs(?) of kit/water/etc is 222 lbs = 15 3/4 stone for the rider. TBH I think it's a pretty conservative limit (because I've been a good bit heavier than that and had no disc brake road problems) so I can't see it being a major issue and I would imagine that bigger rotors for heavier riders would help too.
Nearly 18 stone is quite a lot, isn't it?
It's rider [i]and [/i] bike so if your average bike is 18lbs, then the rider weight limit is 16.5 stone/105kg.
That is still pretty heavy (speaking as a former heavyweight person myself)
Lightweight drum brake....could be tricky, you need a reasonably sized hub shell, brake pads too, no doubt they could come down in weight though.
After using roller & drum brakes on shop commuter bikes, I am pretty convinced they are the way ahead - totally sealed and thus last AGES, very clean also.
*wishes he still did machining class & thinks about signing up again*
I bet it won't be long before the big manufacturers follow my design brilliance with yet more niche bikes.
Swap the tyres and they're there already )
Lightweight drum brake....could be tricky, you need a reasonably sized hub shell, brake pads too, no doubt they could come down in weight though.After using roller & drum brakes on shop commuter bikes, I am pretty convinced they are the way ahead - totally sealed and thus last AGES, very clean also.
*wishes he still did machining class & thinks about signing up again*
Now if you could make an electronicaly activated version that would be a pretty aero solution for the rear disc wheel
Heat dissipation is a problem with drums too, of course - you even used to get such a thing as a tandem coaster brake which was a big drum with cooling fins, intended for tandems going over the Alps.
cynic-al - Member
Lightweight drum brake....could be tricky, you need a reasonably sized hub shell, brake pads too, no doubt they could come down in weight though...
The 90mm Sturmey-Archer drum has pretty good power, it's just heavy at 970gms. About 500gms more than a disk. I'm sure some of that weight could be trimmed on a lathe.
I've been using them on my mtb for the last few years. They've now done 2 'Puffers plus normal mileage and there's no discernable wear on the shoes so they have more than paid for themselves in brake pads. An unexpected benefit is the way they just keep spinning (just like a Campag hub) so there's less drag than with a disk.
The 70mm is lighter at 770gms, and with a bit of trimming could lose a bit of that. Properly setup it would have enough power for road tyred bikes.
We're unlikely to see lightweight drums though. The manufacturers are on too good a thing with the consumables disk brakes require.
Most of the people i've seen round 'ere on high end road bikes will need all of that 18 stone capacity.... 🙄
I think it's great news. Been running original hope cable converters (must have been a decade before the v-twin) on my road bike for years.
I'm sold on the idea and holding out for electronic shifting to trickle down and meet hydraulic braking before I buy another road bike. If they never meet, I'll take the hydraulic brakes over the electronic gears thanks.
If the shifting is just a couple of buttons, hope could make a full lever to caliper set up!
I think wholesale adoption of Disc brakes on road bikes is still some way off, it's telling that SRAM have included a Hydraulic rim brake to try and ease customers into the idea and perhaps accommodate those higher end non-disc frames still on the market.
If rim calipers are removed from road bikes entirely you will see some changes to frame and fork construction (quite possibly no lighter or heavier) but potentially more opportunities for aerodynamic profiling in some areas, the disc brake caliper/lower fork legs could well see a little "sculpting" to try and persuade the aero fan-boyz that discs are aero...
wheel construction will change but again I'm not too sure rim mass will drop too dramatically, and rim profiles may change a bit, it does make tubs a more sensible option for big alpine descents with all the stories of braking heat melting tub glue a receding memory...
It will all change incrementally, and I'm sure you'll see "Disc Ready" road bikes with both sets of mounts on the frame/fork and 135mm hubs but fitted with "Old" style calipers lower down the range...
Just like we did during the initial transition of MTBs from mainly rim to mainly disc braking...
As we know from MTBs Front/rear disc brake performance can be adjusted to the application, for MTB's this has tended towards different diameter front/rear rotors, it looks like SRAM are trying different diameter pistons to balance brakes, interesting...
I've no doubt that Shimano will at some point be pushing some variant of their "Icetech" rotors and pads as the brake of choice for scary Alpine descender's and hence flog loads in surrey and Bucks...
The arguments have been done to death really, and while as an MTBer I am of course very keen I thnk the target consumers (Roadies) have been more reticent and hence the companies looking to flog these technologies are a being a bit more cautious in how they market discs, Considering their accrued knowledge and resources we could have seen these products churned out much faster and forced on the market several years earlier...
I think there's a couple of things going on, first they want the idea that discs on road bikes are a "good" and inevitable thing to percolate through rather than push hard and just achieve a consumer backlash, second they will need to bring the frame/bike manufacturers along with them and allow time for them to wear out their current moulds/jigs and re-tool to make disc compatible frames, finally, I think they want to establish electronic shifting more as a complimentary technology to Discs, hence there's a bit of brinkmanship Shimano and Campag have chucked leccy shifting on the market first as that's arguably easier for consumers to adopt on a current "Standard" bike. SRAM seem to be chucking Hydraulic discs at the market first in an effort to pull users their way with the promise of better braking and hoping they'll see cable actuated gears as more reliable for now, a marginally more risky tactic IMO.
The impression I get is that leccy shifting generally has roadies more excited than Disc brakes, so the first round of adoption may well go Shimano's way, of course what none of them want to be doing for too long is having 3 or 4 variants of Sti in each of their road group;
Leccy gears/mech brakes, Mech gears/mech brakes, leccy gears/hydraulic brakes, Mech gears/hydraulic brakes, that would be a nightmare so at some point Shimano and SRAM will have to start rationalizing things out of their top end groups and then filter than choice down...
I reckon ~2020 Dura Ace will probably only accomodate Leccy shifting and Hydraulic brakes, Ultegra too probably, otherwise the COGs for all those products will just get stupid....
It's all strategic and it's all about the bikes that will be on sale in a decade, not next year's model... IMO of course.
LOL @ freeagent
and of course SS drop barred bikes, at the moment the cable/hydro converters just seem like extra maintenance.If the shifting is just a couple of buttons, hope could make a full lever to caliper set up!
more lefties?If rim calipers are removed from road bikes entirely you will see some changes to frame and fork construction
oooh you cynic 😉Shimano will at some point be pushing some variant of their "Icetech" rotors and pads as the brake of choice for scary Alpine descender's and hence flog loads in surrey and Bucks
oooh you cynic
But I'm probably not too far off
yeah i nearly added "and probably correct" <edit> (not that I see anything wrong with being overbraked)
looking forward to leccy shifting on mtb, hardtails are fine but I find it tricky keeping FSers with dodgy cable routing shifting properly.
looking forward to leccy shifting on mtb, hardtails are fine but I find it tricky keeping FSers with dodgy cable routing shifting properly.
As I said in one of the other threads on this topic yesterday, The bike industry isn't too bad at formulating mechanical interface standards, but I'd actually love to see them put their heads together and develop a standard for interfacing all the electronics that they want to put on MTB's and Road bikes in the not too distant future...
If a common interfacing standard were established before we go too far down the route of having 3 or more differing way's of connecting leccy shifters to mechs then I think it would be an all round good thing...
Ideally such an initiative would allow frame manufacturers to integrate wiring looms during frame production that Shimano/SRAM/Campag users can all attach their kit to, and the whole "plug and play" thing becomes a reality...
Imagine a frame that came with an integrated "bus" and common battery connector to which you could connect shifters, mechs, speed and cadence sensors and a computer, we're not talking implausible sci-fi here, the automotive world has been doing this sort of thing for 20+ years...
But I'm just dreaming, we'll be bodging P-clips and zip ties like we already do for the next fifty years no doubt....
Further discussion from yesterday's thread for anyone that missed it:
http://singletrackworld.com/forum/topic/sram-road-discs
geetee1972 - Member
Nearly 18 stone is quite a lot, isn't it?
It's rider and bike so if your average bike is 18lbs, then the rider weight limit is 16.5 stone/105kg.That is still pretty heavy (speaking as a former heavyweight person myself)
Lighter than Chris Hoy at 93kg.