Any reason not to choose a mechanical disc brake bike?

Discuss light weight issues concerning road bikes & parts.
spdntrxi
Posts: 3019
Joined: Sat Jul 20, 2013 6:11 pm

by spdntrxi

Finx wrote:
Fri Mar 22, 2019 10:00 pm
You also have to be wary of the space between the chain stay and seat stay with the TRP HRD.

I built up a 47cm steel gravel bike for a G/F. She's tiny, so I thought I'd go with the HRD flat mount. Unfortunately, they were too tall to fit under the seat stay on her bike.

I ended up biting the bullet and using Ultegra hydraulic levers and calipers.
you made the right choice.. my wife gets hydro as well.

Phuddy
Posts: 12
Joined: Sat Sep 01, 2018 7:48 pm

by Phuddy

I have TRP Spyre’s on the gravel bike and they do just fine in every situation. Everything on the internet tells you that mechanical discs are the worst thing in cycling and hydraulic discs were sent from the heavens; but it’s all bullshit. Take the budget option that just the job just as well as any other system.

by Weenie


none
Posts: 135
Joined: Mon Dec 17, 2018 11:29 pm

by none

Brakes, who needs them; they only slow you down.
Personally, I prefer the mechanical over hydraulic, since I don't use brakes all that much.
Never have problem slowing down with rim brakes, hydraulic or mechanical disc brakes.. even with long distance, sustained downhill, on or off-raod.

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Lewn777
Posts: 820
Joined: Thu Mar 09, 2017 5:35 am

by Lewn777

I think a reasonably skilled normalish weight rider under 85kg should be just fine on alloy rims and these days you can get alloy wheelsets as light as 1350-1400g, really to go much lighter you're talking about tubs. Mechanical disks can be great, but somethimes aren't (eg Avid BB5 and BB7), and hydros are good too (Shimano 785 etc). I spent years riding hydraulics and mechanical disk brakes on MTBs, but I just don't see the point of adding 300-700g onto road bikes unless you are over 100kg and ride in the rain all the time or have no strength in your hands or some other reason.

TobinHatesYou
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Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

I used Spyre SLCs with my Swiss Cross. They were absolutely fine with Jagwire compressionless link housing and SwissStop pads.

pkaro
Posts: 22
Joined: Mon Oct 01, 2018 2:40 pm

by pkaro

Hexsense wrote:
Fri Mar 22, 2019 9:29 pm
Finx wrote:
Fri Mar 22, 2019 9:19 pm

I'm a fairly big guy. I had mechanical discs on my first disc brake bike several years ago. I thought they were fine right up until they weren't. I burned them up on a really steep gravel descent. I upgraded to hydraulic shortly after and haven't looked back.
I wonder what does hydraulic do anything better than mechanical in term of heat management.

They both heat up with brake energy and dissipate mostly through disc rotor and pads.
If anything, mechanical cable can heat up and be fine. So the whole caliper work as heat dissipator too.
Hydraulic system can heat up and then boil the fluid. That's why many hydraulic brake piston are made of ceramic, to not allow heat to transfer to the calipers (and fluid). Thus more heat trapped in the disc and rotor?
It's most likely the fluid. As you know, fluid is an extremely good thermal sink, and both sram and shimano use fluids with very high boiling points precisely because the fluid does store a ton of energy.

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nickf
Posts: 802
Joined: Sat Mar 06, 2010 10:34 pm

by nickf

My latest build I just reused my sram mechanical 10 speed. Used trp spyre calipers and compressionless housing. I have to say they have plenty of power. Going out and purchasing a full hydro kit would be nice but not necessary. This will also be the bike I travel with. I like the idea of a full mechanical group, can be early serviced anywhere with no worry of having to bleed brakes or charge batteries.

alcatraz
Posts: 2162
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Finx wrote:
Fri Mar 22, 2019 9:38 pm
They are much easier to modulate, and thus allow the rider better control of heat management.

I'm running Hope RX4 calipers with Ultegra levers. I'm also 6' 6" tall and weigh 230lbs.

I find the improved feel and control provided by hydraulic over mechanical to be worth the extra cost.
How much do you think the improvement can be attributed to better materials in pads/rotors, and how much to the fact it being hydraulic.

I can't wrap my head around hydraulic being cooler or less heat sensitive. Maybe someone can help me understand.

Descending the same altitude at similar speed requires the same amount of joules to be converted into heat in pads/rotors. Maybe you were riding much faster when you cooked the brakes last or you were using smaller rotors, or they weren't as heat resistant (pads/rotors).
Last edited by alcatraz on Sat Mar 23, 2019 1:32 pm, edited 1 time in total.

mikemelbrooks
Posts: 36
Joined: Wed Jun 16, 2010 10:58 pm

by mikemelbrooks

I have Shimano 105 and BB7s on my winter bike I can't really see what the improvement would be moving to hydraulics, Adjustment is easy and the only part I have had to replace is a rear brake cable,

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