Can Tiagra Shifter Use with Mechanical Disk Brakes?
 

Hi all,

I have full set Tiagra 4700/4703 rim/v brake 3x10 groupset.

I’m planning to build gravel/cyclocross bike out of it.

However, I’m planning to use disc brakes on the bike.

My question is, can I use Tiagra 4700/4703 shifter with mechanical disc brakes?

I heard/read somewhere it is possible, but the mechanical disc brakes calliper must use the one that is specifically designed for mountain bike, is this true?

And if it is true, can I use that calliper onto the gravel/cyclocross frame?

Thanks in advance🙏

How do you intend to mount the brakes on the frame? That is far more a difficult question to answer as the brake mounts on all my disc brake equipped bikes were designed specifically for disc brakes and have mounting parts integral to the frame. That means they were spaced correctly to mate with the disc.

A cable pull brake lever can be used with mechanical disc brakes. Its quite simple. Tiagra STI will work just fine with cable disc brakes.
As for the claim that an MTB brake caliper is needed, no that isnt the case. Cable brake levers can be used with common cable disc brake calipers like TRP Spyre, Avid BB5, Tektro Aries, etc etc.
The style of caliper mount on your frame(flat mount, post mount, etc) needs to match the disc brake caliper mounts. There are adapters available for some to work together.

Assuming you have disc mounts, yes, you can do this.

However, some of the info you are giving does not add up, and this effects what sort of caliper you should be looking for.

MTB and Road mech disc calipers have different cable pull ratios, and they are meant to be used with the corresponding levers. MTB calipers and levers are “long pull”. Road is “short pull”.

Brake calipers requiring long pull levers include V-Brakes and MTB mech disc brakes.

Brake calipers requiring short pull include traditional Road bike rim calipers, cantilever brakes, “Mini”-V-Brakes, and Road mech disc.

So normally, if someone is using mech discs with drop levers/shifters like you are, the recommendation is to go with Road mech disc calipers.

However, you say that you are currently using V-brakes with your Tiagra levers. Either someone screwed up this setup, or you are incorrect in your description of either your levers or you brake calipers. Are you sure these are not mini-v brakes?

You will need Avid BB5 or BB7 Road calipers.

It can be done but you need 'road' calipers - designed to be used with the shorter cable pull and higher tension than those designed for MTB cables.
It may be possible to operate MTB (long pull) calipers with road (short pull) levers, but the brake will have to be set up with virtually no clearance between the pads and rotors, so rubbing is almost definitely going to be a problem, and housing compression might eat up so much of the already insufficient cable movement that it limits the amount of brake power available.

If you already have MTB calipers and road brake levers, you may be able to adapt one of these https://problemsolversbike.com/index...ch-your-brakes to multiply the amount of cable pull to make the two play better together. However, calipers and levers designed to work together is a better solution.

I have done this. The Tiagra shifters do have shorter cable pull which gives you less room to play with in adjusting the pads so they don't rub. The BB7's will work. I have TRP HYRD's which I like a lot better but I had to install this conversion arm https://www.amazon.com/JJBP-Short-Pu.../dp/B073CCKD85

Just to be clear....

IF the OP needs Road calipers, then he needs Road calipers, which are no more "common" than MTB calipers. And not only would he not need MTB calipers, they would actually be the wrong caliper.

BB5s, BB7s, and Tektro Aries all come in both Road and MTB versions. You have to get the right version of whichever you you go with.

Spyres are all for Road (Spykes are TRP's MTB version of that caliper).

Yeah, you are correct. I sorta assumed it was road calipers the OP would use since it's road shifting and braking. Good to specify though.

Tiagra brake levers are not designed to work with V brakes
What gravel bike frame will you be using? Most current gravel bike frames need flat mount brake callipers, so you will have to look for mechanical brake callipers made for that type of mount.

Hi all,

Thanks so much for all the replies.

Sorry, I think my statement of “rim/v brakes” is confusing.

Basically, I’m currently using this rim brake drop lever/shifter of ST-4700R and ST-4703L, along with calliper of BR-4700.

The frameset that I’ll be using could be some Cyclocross type from Canyon, or the gravel type from Specialized (ie: Crux Expert).

Anyway, so from what I can conclude here, I should be able to use my current drop lever/shifter with any road bike mech disc brake calliper, is it?

And I also need to ensure whether the frameset that I’ll be using is using flat or post mount (i assume the common one always been the former).

Thanks in advance!

I just want to chime in that I've tried road-pull cable disc - and I prefer cantilever brakes. I had one bike set up with mechanical disc, and got rid of it, as the braking was worse than road rim brakes or cantilevers. I built my wife a bike with GRX-400 (Tiagra equivalent) with hydraulic disc - they are such a huge leap over mechanical disc that I would highly recommend going that way, even if you have to go cheaper on a frame or wheelset or wait a bit.

TRP Spyre is your solution

Yep!
Yes, just wait to see what the frame and fork are, then you will know what style of mount you will need.

My Norco Search came equipped with Tiagra levers and TRP Spyres so that combination certainly works.

To directly answer the OP's statement-question "Anyway, so from what I can conclude here, I should be able to use my current drop lever/shifter with any road bike mech disc brake calliper, is it?" No, the STI Tiagra shifter is not compatible with just any caliper. I know this from direct experimentation with Spyre calipers and Tiagra 10 speed brifters. It did not work well at all, in fact it is better to simply say they did not work. Not enough cable pull in the levers.

I also tried it with BB7 calipers and it did not work. Both the Spyre and BB7 calipers were MOUNTAIN calipers and require more cable pull. The BB7 caliper does come in a ROAD version and is intended to be compatible with road bike brake levers. I don't know for sure, but my guess is the Spyre calipers are available as road calipers as well, but find out for sure before ordering.

Again, I experimented with this myself and the results for both Spyre and BB7 mountain calipers were a failure when mated to Tiagra STI road bike brake/shift levers.

Spyre is a Road caliper. Spyke is the MTB version of the Spyre.

Countless people are running Spyres with road levers. Widely considered the best Mech disc caliper for Road.

I had Spyres that came spec'd with my Tiagra 4700 equipped bike from Giant. They worked but I never liked them, tried upgrading to TRP HY/RD. Better but still far, far worse than full hydraulic. And yes, Giant used Jagwire compressionless brake housing, as did I with fresh housing when I installed the HY/RD caliper. I've seen it said that the Spyres and HY/RD are the best mechanical disc brake options, which didn't inspire any confidence.

Maybe I needed to experiment with more pads and rotor combinations, but I bought two full hydro bikes after that Giant and sold it to thin the herd, so my mechanical disc brake experience is over for good.

"Spyre is a Road caliper. Spyke is the MTB version of the Spyre"

I must thank you for the clarification. The Spyre calipers I moved from a Kona mountain bike to a road bike where not marked Spyke, instead they were marked Spyre. Whatever the case if what you note is correct, then the error is mine. Perhaps I read the name printed on the caliper incorrectly. My apologies for the misinformation.

Even a low-end hydraulic system will feel better than a high-end cable system. But there's the questions of lever compatibility, and (opinions may vary) I think think hydraulic levers are ugly.

I have the same set, and I bought TRP Spyres for my bike. If I was to make the same decision again, I would probably go TRP Hy/Rd, as the springs in the Spyres are quite strong...

https://cimg0.ibsrv.net/gimg/bikefor...81e44d201f.jpg