yo y mis circunstancias: frenos de disco hidràulicos Shimano R785 para carretera

miércoles, septiembre 18, 2013

frenos de disco hidràulicos Shimano R785 para carretera

https://www.facebook.com/CycleXpress/posts/571022406292956

https://www.facebook.com/CycleXpress/posts/571161572945706

https://www.facebook.com/CycleXpress/posts/571107459617784

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Interbike

fuji

carrete zipp con rodamientos grandes, rueda con disco para èse carrete

http://www.slowtwitch.com/Lifestyle/2013_Interbike_-_Day_2_3905.html

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dar siempre, sin esperar nada a cambio...

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Shimano specifics that its ICE rotors be used with the R785 levers and calipers

Shimano R785 hydraulic brakes and Di2 shifters - first ride
By Ben Delaney

In June, BikeRadar first broke down the details on Shimano's new electric/hydraulic levers that can be paired with hydraulic brakes and a Di2 drivetrain. At Interbike's Outdoor Demo, we had the chance to ride the system with Ultegra Di2 and were pleasantly surprised. The levers feel very similar to standard Di2 levers in ergonomics and braking performance — but with less hand force required.

Shimano has yet to release pricing, so an apples-to-apples comparison isn't yet possible. But at first blush, we prefer Shimano's hydraulic road sytem to SRAM's.

Pros: Great ergonomics - identical with Di2 levers; reach and stroke adjustments; brake lever action feels like mechanical - but stronger
Cons: Tinny, rattling sound when riding with hands on tops (without cables, the lever head has nothing to pull it snug against the hood body); lack of standard Shimano tiered branding (it's not Dura-Ace, it's not Ultegra, so what is it?); dull finish
Shimano specifies that the r785 leves and calipers be used with its ice rotors. while debate remains on whether 140 or 160mm is best for road applications, shimano has chosen 140mm :

Shimano specifics that its ICE rotors be used with the R785 levers and calipers

There are a few notable differences between Shimano's hydraulic road system and SRAM's. Most obvious is the lever shape; using electric shifting frees up considerable real estate for the hydraulic internals for Shimano, while SRAM stacks its reservoir on top of a mechanical design.

Another difference is the strategy and presentation. SRAM launched hydraulic road brakes at the top of its food chain with Red 22 (and also the lower, non-series S-700), while Shimano has begun with only a non-series R785 lever that is neither the top-level Dura-Ace or the second-tier Ultegra. Why? Shimano spokesman David Lawrence said that the company isn't yet satisfied with the product, and feels that improvements in performance, weight and finish must be made before it can be branded Dura-Ace.

And in fact, this system is still a work in progress, with the hubs and calipers essentially being XT mountain models. Shimano has entered other categories in similar fashion before. Its first compact crank was the R700 — not an Ultegra or a Dura-Ace. And its first hydraulic mountain bike brake was an XT - not the top-of-the-line XTR.

One mildly irritating point is the tinny rattle caused by the lever head vibrating against the body of the hood when riding over rough surfaces with your hands on the tops. When riding on the hoods, your hands absorb the vibration and eliminate the problem. But unweighting the hoods, when road conditions are choppy, results in noticeable noise. The reason for this is that hydraulic road levers (both Shimano and SRAM) by design lack the cable tension inherent in mechanical systems, so there is nothing holding them taut in place.

Braking feel and adjustability

Braking on the road, the Shimano R785 levers and hydraulic feel similar to Dura-Ace mechanical calipers in terms of ratio of lever pulled to brake force applied at the wheel. With SRAM's Red 22 Hydro-R system, the levers have to be pulled noticeably more for the same amount of braking. In both cases, the finger force required is noticeably less than a mechanical system.

Whether using the brakes to shave off a little speed or to pull up quickly for an abrupt stop, the system engages quickly and predictably, with plenty of throw left at the lever.

The shimano r785 lever with the reach adjust dialed all the way in:

The levers can be substantially adjusted for reach and mildly adjusted for free stroke

The levers can be adjust for reach (how far the lever sits in neutral position from the handlebar) and what Shimano calls free stroke (the point in the pull of the lever at which the brakes begin to engage). Both adjustments are made with screwdrivers underneath the hood.

The brakes use Shimano's mineral oil, and servicing them is identical in process and tooling to the company's mountain bike brakes.

Where this will pop up

As the R785 system is becoming available later this year, cyclocross bikes will be the first to arrive with the product as original equipment. Then road bikes will begin trickling out with Ultegra Di2 and perhaps Dura-Ace Di2 and hydraulic brakes. Its potential adoption for sales as a standalone group, if it comes, will be months if not years away.

There are no two ways about it, a hydraulic road brake system is heavier than a mechanical rim caliper system. Lawrence said Shimano's system adds roughly 300g — not including additional potential weight on the frame and the fork. With Shimano's rim brakes already quite functional, many riders and even many shop owners are asking, what is the point? Shimano, as with SRAM, points to 'consistent braking across all conditions,' and 'better modulation and more power for less finger input.' But ultimately you, the rider, will dictate whether this system truly takes off or if it remains a novelty.

http://www.bikeradar.com/road/gear/category/components/groupset/groupset-road/product/review-shimano-r785-electronichydraulic-system-47604

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