Disc Front Brake / Rim Caliper Rear Brake Experiment

mrwirey · Dec 17, 2015

So here goes nothing:

My Hypothesis: Since most of a bike’s stopping power is found in the front wheel and discs provide superior stopping power/modulation under most conditions; running a disc brake front/rim caliper rear brake set up should provide a better balance of stopping power and modulation when compared to the same bike with rim brakes front and rear while avoiding the weight penalty (arguably slight) and complexity associated with a full disc setup. (… okay … so I’m bored…)

My Control Bike: 2012 Cannondale CAAD10-1 with full Shimano Dura Ace 7800 10 Speed Group and H-Plus Son Archetype Rims laced to Ultegra 6800 Hubs

My Test Mule: 2012 Cannondale CAAD10-1 with Shimano full Dura Ace 7900 10 Speed Group.

The Relevant Test Components:
- The Test Mule
- 2015 Cannondale Synapse Disc Carbon Fork
- 2015 TRP HY/RD Hydraulic Front Disc Brake Caliper with 140mm TRP Disc
- 2012 Shimano Ultegra 6700 Rear Brake caliper with Corima Red Brake Pads
- 2015 25mm Carbon Clincher Wheelset (new off eBay); Front is Disc Compatible; Rear is Standard Rim Brake Compatible (I’m still waiting on the wheels, but I should have this thing together by X-mas)

Wish me luck!

Very respectfully, Tim

SwiftSolo · Dec 17, 2015

Tim,
I think it is a great experiment. We can only guess what the outcome will be.

My gut feeling is that initially. the rear will contribute very little and as the rim gets scrubbed dry, you may find the rear wheel locking up untill you reduce lever pressure. Even if that happens, you may be able to adapt.

Let us know and don't give up on it until you've tried it enough to have a shot at adapting.

Do you ride on downhills with hairpins?

mrwirey said:
So here goes nothing:

My Hypothesis: Since most of a bike’s stopping power is found in the front wheel and discs provide superior stopping power/modulation under most conditions; running a disc brake front/rim caliper rear brake set up should provide a better balance of stopping power and modulation when compared to the same bike with rim brakes front and rear while avoiding the weight penalty (arguably slight) and complexity associated with a full disc setup. (… okay … so I’m bored…)

My Control Bike: 2012 Cannondale CAAD10-1 with full Shimano Dura Ace 7800 10 Speed Group and H-Plus Son Archetype Rims laced to Ultegra 6800 Hubs

My Test Mule: 2012 Cannondale CAAD10-1 with Shimano full Dura Ace 7900 10 Speed Group.

The Relevant Test Components:
- The Test Mule
- 2015 Cannondale Synapse Disc Carbon Fork
- 2015 TRP HY/RD Hydraulic Front Disc Brake Caliper with 140mm TRP Disc
- 2012 Shimano Ultegra 6700 Rear Brake caliper with Corima Red Brake Pads
- 2015 25mm Carbon Clincher Wheelset (new off eBay); Front is Disc Compatible; Rear is Standard Rim Brake Compatible (I’m still waiting on the wheels, but I should have this thing together by X-mas)

Wish me luck!

Very respectfully, Tim

ogre · Dec 17, 2015

What are you trying to do? Piss off the disc brake fanatics AND the rim brake diehards all at the same time?

Fredrico · Dec 18, 2015

mrwirey said:
So here goes nothing:

My Hypothesis: Since most of a bike’s stopping power is found in the front wheel and discs provide superior stopping power/modulation under most conditions; running a disc brake front/rim caliper rear brake set up should provide a better balance of stopping power and modulation when compared to the same bike with rim brakes front and rear while avoiding the weight penalty (arguably slight) and complexity associated with a full disc setup. (… okay … so I’m bored…)

My Control Bike: 2012 Cannondale CAAD10-1 with full Shimano Dura Ace 7800 10 Speed Group and H-Plus Son Archetype Rims laced to Ultegra 6800 Hubs

My Test Mule: 2012 Cannondale CAAD10-1 with Shimano full Dura Ace 7900 10 Speed Group.

The Relevant Test Components:
- The Test Mule
- 2015 Cannondale Synapse Disc Carbon Fork
- 2015 TRP HY/RD Hydraulic Front Disc Brake Caliper with 140mm TRP Disc
- 2012 Shimano Ultegra 6700 Rear Brake caliper with Corima Red Brake Pads
- 2015 25mm Carbon Clincher Wheelset (new off eBay); Front is Disc Compatible; Rear is Standard Rim Brake Compatible (I’m still waiting on the wheels, but I should have this thing together by X-mas)

Wish me luck!

Very respectfully, Tim

Just be careful not to go over the handlebars!

SwiftSolo · Dec 18, 2015

That's good advice but I doubt that would be an issue with TRP's--depending on the lever. Even with shimano hydros, it only takes a few stops to generally adapt. Takes much longer to learn how to take full advantage on twisting mountain descents. I'm guessing I have maybe 4000 hairpins under my belt on road hydro discs and I still feel I'm on the steep part of the learning curve.

Fredrico said:
Just be careful not to go over the handlebars!

upstateSC-rider · Dec 18, 2015

I have an old school mt bike set up like that, Avid BB-7 in the front and V-brake in the back, the only reason it's not full disc is because it doesn't have disc mounts in the rear.
Works better than full V-brake but still way less power than even low-end hydro discs.

mrwirey · Dec 18, 2015

SwiftSolo said:
Tim,
Let us know and don't give up on it until you've tried it enough to have a shot at adapting.

Do you ride on downhills with hairpins?

Swiftsolo,
Thank You for the encouraging words and don't worry ... I won't give up easily. This will be a dedicated project bike so no need to revert back to original.

I don't have many steep hairpins, but I do have steep, somewhat sketchy - due to gravel - roads. I may take a trip to Mt. Graham as it is very steep with lots-o-hairpins on the descent. That would be a very good test of the set up.

I'll report my findings once I have some.

Very respectfully, Tim

mrwirey · Dec 18, 2015

ogre said:
What are you trying to do? Piss off the disc brake fanatics AND the rim brake diehards all at the same time?

ogre,
I know, right? :thumbsup:

Very respectfully, Tim

mrwirey · Dec 18, 2015

upstateSC-rider said:
I have an old school mt bike set up like that, Avid BB-7 in the front and V-brake in the back, the only reason it's not full disc is because it doesn't have disc mounts in the rear.
Works better than full V-brake but still way less power than even low-end hydro discs.

upstateSC-rider,
Good to hear you've done it. I did a lot of googling, but couldn't find anyone who'd really tried this on a road bike so it got me curious. I'm trying not to presuppose the outcome. I'm sure it will look a bit odd, but I'm hoping for the best.

Very respectfully, Tim

BCSaltchucker · Dec 18, 2015

ogre said:
What are you trying to do? Piss off the disc brake fanatics AND the rim brake diehards all at the same time?

Zing!

I love it.

actually he only pisses off me. I am that guy who would run disk hydro ont he back, and cable brake on the front. I did just that 20 years ago on a DHfreeride bike (RockyMtn DHRace, with Hayes hydro rear disk,and Avid front cable brake). Did not want so much power in the front to prevent endo-ing, but I did want very good power and modulation for the rear. Extremely steep crude trails.

The thing is, front brakes always felt to have more power and modulation not just because of the leverage advantage of front brakes, but also because the cable and housing is so short you get a lot less sponginess, compared to back cable brakes. So it is nicer having the hydro feel in the rear, imho, if you can only have one brake. (at the time disk brakes hard to come by and frames and forks were not equipped with mounting tabs - I made my own mount)

yancy0303 · Dec 18, 2015

I also rode this setup on an old mt bike. I believe it was referred to as a "mullet setup", all business up front and a party out back.

Jay Strongbow · Dec 18, 2015

mrwirey said:
So here goes nothing:

My Hypothesis: Since most of a bike’s stopping power is found in the front wheel and discs provide superior stopping power/modulation under most conditions; running a disc brake front/rim caliper rear brake set up should provide a better balance of stopping power and modulation when compared to the same bike with rim brakes front and rear while avoiding the weight penalty (arguably slight) and complexity associated with a full disc setup. (… okay … so I’m bored…)

From what I can understand you have it backwards. If the front is stronger than the rear (aka not balanced stopping power when using the same brakes) using a stronger brake on the front will only throw that balance off further not bring the power more into balance.

SwiftSolo · Dec 18, 2015

I think the difference is that traction is very limited on steep dirt descents. Because the gradient is often twice as steep as anything we see on road bikes, a disproportionate amount of the weight/traction is on the front, even when behind the seat.

On the pavement, steep, sharp turns put even more or the resistance on the front wheel. Braking hard with your ass behind the seat will still make it hard to keep much weight on the rear tire.

With hydro disc, precision makes trying to find the balance interesting. On dry pavement, you can hear your rear tire squawking a bit just before breaking loose and you can maintain that level of braking. Beyond that point, more pressure on the front brake will cause the rear tire to break loose as will more pressure on the rear brake. Your only option is to get further behind the seat if you need to increase deceleration.

Look for ex mountain bikers to gain an even bigger advantage on technical road descents in the Giro and Tour this year.

BCSaltchucker said:
Zing!

I love it.

actually he only pisses off me. I am that guy who would run disk hydro ont he back, and cable brake on the front. I did just that 20 years ago on a DHfreeride bike (RockyMtn DHRace, with Hayes hydro rear disk,and Avid front cable brake). Did not want so much power in the front to prevent endo-ing, but I did want very good power and modulation for the rear. Extremely steep crude trails.

The thing is, front brakes always felt to have more power and modulation not just because of the leverage advantage of front brakes, but also because the cable and housing is so short you get a lot less sponginess, compared to back cable brakes. So it is nicer having the hydro feel in the rear, imho, if you can only have one brake. (at the time disk brakes hard to come by and frames and forks were not equipped with mounting tabs - I made my own mount)

AJ88V · Dec 18, 2015

Disc front, cantilever rear was a very common setup on mountain bikes for awhile, especially for lower end bikes trying to keep the price down when disc brakes were becoming the standard and not the exception.

I'm not sure you'll see that big a difference in feel with the TRP hy/rd vs your excellent Ultegra rear setup, but since I've never straight-up compared a road caliper to a road disc, it will be very interesting to see what your impressions are. :thumbsup:

FWIW, I'm about to install a pair of Hy/Rds on my CX bike (parts came in last night). The mechanical discs absolutely suck (too used to hydros on my MTB). My son has the SRAM hydros on his CX and they feel very much like good MTB brakes (meaning wunderbar!).

mrwirey said:
upstateSC-rider,
Good to hear you've done it. I did a lot of googling, but couldn't find anyone who'd really tried this on a road bike so it got me curious. I'm trying not to presuppose the outcome. I'm sure it will look a bit odd, but I'm hoping for the best.

Very respectfully, Tim

You're using your CAAD10 on gravel? Pretty skinny wheels/tires for that. I've had more than enough pinch flats on my CX in the past year running 35mm tires. LOL!

Good luck with your experiment. - v/r, AJ

deviousalex · Dec 18, 2015

I was considering this for my CX bike. It has both canti and disc mounts but the rear is 130mm spaced (not 135mm) so it's hard to find disc brakes that work for it. Problem is then I'd have so many front wheels I don't need!

mrwirey · Jan 4, 2016

Frankendale is alive!!!!

Bike is all together. I rode it for the first time today. Bottom Line: My initial impression is their is negligible difference between the Shimano Ultegra caliper front brake and the TRP HY/RD I replaced it with. Both work equally well. Granted, I have yet to really stress the bike in nail biting braking situations, but I don't think I will really appreciate the front disc until I get caught in a downpoor. Operative word being 'caught' as I don't ride in the rain by choice. I will provide more insights as I put more miles on the setup.
Very respectfully, Tim

bvber · Jan 4, 2016

mrwirey said:
My initial impression is their is negligible difference between the Shimano Ultegra caliper front brake and the TRP HY/RD I replaced it with.

If the disc brake pads are new, it will take a bit of time to develop its stopping efficiency to full potential. It did with mine.

mrwirey · Jan 4, 2016

bvber said:
If the disc brake pads are new, it will take a bit of time to develop its stopping efficiency to full potential. It did with mine.

bvber,
I guess I should've held off judgement until the disc pads were fully broken in. I'll continue to bed them in and evaluate. Thank You.

Very respectfully, Tim

jeffpoulin · Jan 4, 2016

mrwirey said:
... but I don't think I will really appreciate the front disc until I get caught in a downpoor. Operative word being 'caught' as I don't ride in the rain by choice.

I applaud your experiment, but I must admit that I'm missing the point of having a front disc for fair weather riding. In dry conditions, my calipers work as well as my discs. I only notice a difference when riding in the rain (which I do regularly as a bike commuter). Maybe for those few times when you're caught, as you said.

mrwirey · Jan 4, 2016

jeffpoulin said:
I applaud your experiment, but I must admit that I'm missing the point of having a front disc for fair weather riding. In dry conditions, my calipers work as well as my discs. I only notice a difference when riding in the rain (which I do regularly as a bike commuter). Maybe for those few times when you're caught, as you said.

jeffpoulin,
I was in a bike race last year, which had patches of intermittent rain. I was riding my Madone with Boyd full carbon clinchers and I kept forgetting my brakes didn't work as well in the wet as they do in the dry. :blush2: The worse that happened was I unintentionally went to the front of the paceline when the guy in front of me suddenly slowed, but it got me thinking about having a disc equipped race bike for just such occasions.

Although this bike will probably be very niche in the larger scheme of things, I'm sure it will be worthwhile at some point. It's all about N+1 anyway, right? :thumbsup:

Very respectfully, Tim

Disc Front Brake / Rim Caliper Rear Brake Experiment

mrwirey

SwiftSolo

ogre

Fredrico

SwiftSolo

upstateSC-rider

mrwirey

mrwirey

mrwirey

BCSaltchucker

yancy0303

Jay Strongbow

SwiftSolo

AJ88V

deviousalex

mrwirey

bvber

mrwirey

jeffpoulin

mrwirey

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