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Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 6:09 pm
by Multebear
I have two rimbrake roadbikes, which work fine, but I'd like to replace one of them with a DB bike.

There might be an option for me to buy a fairly priced DB frame. I have a rimbrake di2 groupset, and it would be easy to just install that to the DB frame with TRP Spyre brakes. I have a pair of DB wheels for the cx bike already, that I would be able to use on the DB roadbike.

I'm not going to go hydro disc for road, since that is too expensive, and then I might as well just keep the two rimbrake roadbikes.

The reason for replacing one of them with DB bike is, that it would be nice to have discs for foul weather and for my yearly trips to the south european mountains.

Any reason not to do this?

This is not a rimbrake vs. discbrake question. It's more like; is it really worth it to go hydro discs if you have almost all the parts (except the frame obviously) for a mechanical disc brake bike?

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 6:13 pm
by Hexsense
TRP Spyre aren't that powerful.
Try Juin tech F1 (flat mount) or R1 (post mount). It's stronger than Spyre but not as strong as real full hydraulic (cable friction is still there, so stronger return spring needed).
It weight similarly to the Spyre (not as porky as TRP Hyrd).

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 6:13 pm
by Weenie

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 6:15 pm
by fromtrektocolnago
Never mind. I mis-read the quesiton.

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 6:56 pm
by kode54
I just can't believe how much the 9170 costs. So if its a matter of cost, maybe. But are you really saving that much more?

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 7:01 pm
by dricked
PM sent, I may have some parts you’d be interested in.

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 7:08 pm
by Jugi

Multebear wrote:I have two rimbrake roadbikes, which work fine, but I'd like to replace one of them with a DB bike.

There might be an option for me to buy a fairly priced DB frame. I have a rimbrake di2 groupset, and it would be easy to just install that to the DB frame with TRP Spyre brakes.
I think that is the only scenario where mechanical disc brakes actually make sense (as in using the mechanical calipers as a stop-gap between frame and groupset compatibility).

In general, mechanical disc brakes combine the bad features of mechanical and hydraulic brakes. Lack of modulation and can be hard to adjust. Maintenance should be easier than hydraulic, but most likely there should be more of it.

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 7:51 pm
by petromyzon
FWIW I really like my Spyre SLCs. You need nice compressionless housing runs but otherwise they work well. I've never used a true full hydraulic system but I don't think you would be disappointed considering the money you are likely to save. The power, modulation and particularly wet weather performance is still better than any of my rim brake rigs.

Quality brake pads and decent full fat 160mm discs are probably the way to go though, I wouldn't start using weight weenie bits.

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 8:03 pm
by Multebear
I have no problem with braking on my cx bike with the Spyres. Having good modulation is fine, but IMHO not worth paying that much extra $$ - and on the roadbike it makes even less sense for me. I don't need better stopping power on the roadbike than I have with rimbrakes. I just need to avoid overheating of the rims on descents and better braking in the wet.

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 8:42 pm
by spdntrxi
kode54 wrote:
Fri Mar 22, 2019 6:56 pm
I just can't believe how much the 9170 costs. So if its a matter of cost, maybe. But are you really saving that much more?
agree... and further more for TT bikes the levers are ugly. (R9180).. I'm using sprye on my TT bike with 9071 Di2/mech levers.. The spryes do alright.

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 9:19 pm
by Finx
How heavy are you?

What are your typical rides like in terms of terrain?

Are you fairly experienced ? Have good riding skills?

Mechanical discs are adequate for many situations, but if you are particularly heavy, riding a loaded rig, or ride particularly long descents, you will definitely appreciate what hydraulic discs have to offer.

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.

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 9:29 pm
by Hexsense
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?

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 9:38 pm
by Finx
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.


Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 9:50 pm
by Mr.Gib
I have a fair amount of experience with TRP Spyre, TRP HYRD, and JuinTech, as well as a couple of different Shimano full hydro set-ups. The thing to remember is that stopping power is a combination of the friction between the pad and rotor and the amount of effort applied to the lever. Regardless of brake type, you can optimize the pad/rotor interface by choosing what works best for your application. That just leaves how hard your fingers have to work. In theory the TRP Spyre can stop as quickly as the very best full hydro system, you would just have to squeeze the levers a lot harder. (I'm ignoring modulation as an advantage as I can't ever recall struggling with modulation on any road braking system).

So to address the question, no absolutely nothing wrong with mechanical in a road application. As has been pointed out in various places, the order of stopping power at a given lever effort is HYRD > JuinTech > Spyre. I had one HYRD equipped bike that was the match of most full hydro systems. Semi-metalic pads worked best for me. It's a shame they are heavy, expensive and massive looking (the post mount is OK but the flat mount version is a bit silly looking).

One additional caution, with JuinTech and HYRD, you need to look very carefully at where the rear brake cable exits the frame relative to where the cable enters the caliper. Some frames are almost a no-go due to the servere cable bend required.

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 9:57 pm
by Multebear
I'm beween 82 and 88 kg depending on fitness level. When I'm not travelling, I only ride flats. No mountains here. I'd say I'm experienced enough with very good bike handling skills. I'm not worried about modulation and overheating. As mentioned I have a cx with Spyres, and I have no problems even on very technical courses. I'm not pro level, so modulation is not winning me races. And seriously, how important is modulation on a roadbike. If you're braking on a roadbike, you don't win races.

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 9:57 pm
by Weenie

Re: Any reason not to choose a mechanical disc brake bike?

Posted: Fri Mar 22, 2019 10:00 pm
by Finx
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.