Need assistance w/ 2x front brakes.

[loysius]

Hi guys,

So I've got the DNM USD-8 Front Fork and a front hub that can mount dual rotors. What I have been looking for is a good system that I could use to with one grip brake with 2 calipers. At first I thought I was going to mount two mechanical brakes and use this neat double brake hand grip but then I realized the brake caliper for the right side would need to be a mirror of the one on the left. Well luckily I found this awesome set made by Tektro but I am having the hardest time finding a vendor I can buy it from. I've shot Tektro a couple emails but they aren't responding. The only vendor I've found so far seems to be a German vendor and the brake cables seem to be quite excessively long with a total length between handlebar and caliper being like 2450mm(8ft) which is wayy too long. Here is a link https://www.bike24.com/1.php?content=8;product=127005;menu=1000,2,15,117;page=104

What do you guys suggest?


Links to fork and hub:
Fork: DNM USD-8: http://em3ev.com/store/index.php?route=product/product&path=47_48&product_id=214
Front Hub: http://vectorebike.com/orders/componencts.html
Disc brake rotors: https://www.amazon.com/gp/product/B013QSUXY0/ref=crt_ewc_img_dp_1?ie=UTF8&psc=1&smid=A1LD3YCR5X6YMM
Informational page for Tektro Front Dual Disc Calipers: http://www.tektro.com/_english/01_products/01_prodetail.php?pid=226&sortname=Disc&sort=1&fid=1

You'll notice that on the Tektro informational page 750mm(2.5ft) cable length is a much better fit for the DNM USD-8 fork.

Thank you,
Al

 

[_g_]

I know it's not what you've asked and you're quite a way down the double-brake route, but do you definitely need two?

Generally a high spec hydraulic brake I would expect to offer more than two mechanical calipers.

Which leaves heat as the remaining issue.

If it is an issue, you could also look to other solutions for that.

Having owned, ridden and raced various small capacity motorcycles - it's usually only cheap ones going for show that have twin setups at the front.
Anything serious does just fine with a single disc.

Bigger bikes where you're having to regularly stop from 140mph+ on track, twin discs do make a lot of sense!

 

[loysius]

I know it's not what you've asked and you're quite a way down the double-brake route, but do you definitely need two?

Generally a high spec hydraulic brake I would expect to offer more than two mechanical calipers.

Which leaves heat as the remaining issue.

If it is an issue, you could also look to other solutions for that.

Having owned, ridden and raced various small capacity motorcycles - it's usually only cheap ones going for show that have twin setups at the front.
Anything serious does just fine with a single disc.

Bigger bikes where you're having to regularly stop from 140mph+ on track, twin discs do make a lot of sense!

You're right, I would definitely do fine with just one. I was originally going so hard for it because I planned on doing two mechanical instead of 1 hydraulic but the only setup I've found uses hydraulic so I went from seeking 2 mechanical Avid BB7 calipers to the Tektro solution. I really look forward to having less wear and tear. My back wheel will have regen braking and my front would have two calipers sharing the load. I need the bike to stop from 60mph not 140 lol but these are also bicycle brakes, I really want to make this happen after going out of my way for some of the components. If my only route is to buy this 8ft version of the kit and redo all the cables then that will have to work.

 

[nutnspecial]

Have you searched this site 'for sale'? I think zombiess was selling them along with the forks within a year.

You bought from em3 (fork, hub) I think, did they have a recommendation?

I agree, if you already have the fork and hub. . . why not?
Less wear, possible wheel stands . . .

 

[MadRhino]

I know Magura has the parts to operate 2 brakes with one lever, but they might be much more expansive than Tektro.

I love the look of dual disc, but not the weight of both: The fork that makes it possible, and the extra brake.

I use a Boxxer WC Solo AIR (6 Lbs 4 Ounces) with a 225mm Hope rotor and a Magura MT7. Almost perfect combination for light weight and braking performance.

 

[loysius]

Great news guys,

Vectorebike sells the Tektro Auriga e-Twin brake calipers. Got a pair that is the proper length for the front fork thanks to them. Just waiting for it to arrive now. They sell the 203mm rotor version but you'll have to contact them by email for it. http://www.vectorebike.com/uprgade.html

Thanks for the help everyone

Sincerely,
Al

 

[MrDude_1]

I know it's not what you've asked and you're quite a way down the double-brake route, but do you definitely need two?

Generally a high spec hydraulic brake I would expect to offer more than two mechanical calipers.

Which leaves heat as the remaining issue.

If it is an issue, you could also look to other solutions for that.

Having owned, ridden and raced various small capacity motorcycles - it's usually only cheap ones going for show that have twin setups at the front.
Anything serious does just fine with a single disc.

Bigger bikes where you're having to regularly stop from 140mph+ on track, twin discs do make a lot of sense!

heat is a big issue when you're a big guy and you're trying to haul a heavy bike down from 50+mph.
Dual hydraulic is really the only way to go IMO.... unlike a motorcycle that has a thick rotor, all these rotors are very thin, with very small swept area under the pads... so they overheat quickly.
running a larger rotor helps, but they still overheat easily... running dual rotors cuts that issue in half.


as far as "only cheap once for show".. all modern performance motorcycles run a dual rotor on the front.

 

[MadRhino]

heat is a big issue when you're a big guy and you're trying to haul a heavy bike down from 50+mph.
Dual hydraulic is really the only way to go IMO.... unlike a motorcycle that has a thick rotor, all these rotors are very thin, with very small swept area under the pads... so they overheat quickly.
running a larger rotor helps, but they still overheat easily... running dual rotors cuts that issue in half.


as far as "only cheap once for show".. all modern performance motorcycles run a dual rotor on the front.

Big guys are not 500 Lbs, and ebikes are not speeding 200 Mph (yet ).
Saying dual front brake is the only waty to go, is very exagerated. A quality single brake with large pad surface and a 225mm vented rotor, does much better than the dual Tektro we're talking here, both in braking distance achieved and heat management. Then, a quality dual front brake is definitely better, but way overkill for a 60 Mph ebike even if it is riding very aggressively.

Hope vented rotor

Comparison Tektro auriga vs Magura Mt 7

 

[nutnspecial]

Brass tax, what is the cost of tektro x2 brakes VS the hope vented and 4 piston?

The necessary fork and hub are a sidebar for me, for now.

 

[loysius]

Brass tax, what is the cost of tektro x2 brakes VS the hope vented and 4 piston?

The necessary fork and hub are a sidebar for me, for now.

The Tektro x2 were 180 usd from vectorebike.com

 

[MadRhino]

I never said it was cheap, high performance and weight saving have a cost. Yet, one used Saint Caliper and a 225mm Hayes rotor are about the price of the pair of new Tektro, so it can be done for a reasonable price.

New pair of the best brakes and 225mm vented rotors ?
Busting the 1000$

I agree that the dual tektro will do the job, and it will have a killer look. It is a heavier setup, but still a major improvement to your bike at a very reasonable cost.

 

[Chalo]

as far as "only cheap once for show".. all modern performance motorcycles run a dual rotor on the front.

Lots of motorcycles that gross 800 to 1000 lbs all up, and go faster than highway speed, get by just fine on a single front disc and a rear drum. On a bicycle, getting symmetrical left and right calipers limits you to much less than the best performing units.

It's important to keep in mind that the narrow flange spacing of a dual rotor front wheel makes the wheel substantially weaker and less stiff. So there's a cost of something you might actually need that you trade away in return for an imaginary benefit (that in reality probably diminishes your braking performance too).

If everything that's best for a motorcycle were best for your bicycle, that would mean your bicycle is a motorcycle. It isn't.

If I needed the utmost in braking performance, I'd use aluminum rotors 630mm in diameter, weighing about a kilogram each. Not only would they offer far more heat capacity and surface area for thermal transfer, but the brakes they work with are much cheaper, more reliable, and easier to maintain than little weenie sub-250mm disc brakes. Plus, the big rotors are already on my bike whether I use them for braking or not.

 

[MrDude_1]

If everything that's best for a motorcycle were best for your bicycle, that would mean your bicycle is a motorcycle. It isn't.

It would be if I could afford to put the best parts on it.

Seriously, it does 50mph, has suspension, and I ride it on the street with traffic. The only thing it is lacking is the legal status.

 

[Chalo]

To put it in perspective, the Honda CB750 had a top speed of about 125mph, gross weight rating about 950 pounds, and was equipped with a single front disc and rear drum brake from the time it appeared in 1969 until it went out of production in 2007.

Tell me again why any bicycle needs dual front discs?

 

[loysius]

To put it in perspective, the Honda CB750 had a top speed of about 125mph, gross weight rating about 950 pounds, and was equipped with a single front disc and rear drum brake from the time it appeared in 1969 until it went out of production in 2007.

Tell me again why any bicycle needs dual front discs?

What is there to argue about? Heat dispersion from 2 rotors together is faster than 1 rotor. If you read about that $120 225mm hope rotor you'll see that with it's fancy design it only gets up to 15% faster heat dispersion. The larger circumference is the biggest benefit to heat dispersion yet it still can't compare to dual rotors. There is more benefit to stopping power because of the larger radius to the 225mm disc but here I'll lay it all out.

Legend for variables:
{
Heat Cooling Off Rate = (diameter/203mm)*(total number of rotors) /(the number of pistons squeezing each rotor)
Stopping Power = (Radius of rotor/101.5mm) * (number of pistons squeezing the rotor) * (the number of rotor/brakes combos used)
}

Single hydraulic brake: #USED AS BASELINE //just a regular single piston hydraulic brake
203mm rotor x1, single piston caliper x1
{
Heat Cool Off Rate = 203/203*1/1 = 1 //a higher number is better
Stopping Power = 101.5/101.5*1*1 = 1 //a higher number is better
}

Dual hydraulic brakes: //my choice
203mm rotor x2, single piston caliper x2
{
Heat Cool Off Rate = 203/203*2/1 = 2 //a higher number is better
Stopping Power = 101.5/101.5*1*2 = 2 //a higher number is better
}

Hope brake:
225mm rotor x1, double piston caliper x1
{
Heat Cool Off Rate = 225/203*1/2 = .554 //a higher number is better
Stopping Power = 112.5/101.5*2*1 = 2.217 //a higher number is better
}


Since there is such a big price difference between double hydraulic and the hope + their $120 rotor.. why would I go that route? Because it isn't necessary to go dual brakes? Sure you can say dual hydraulic brakes aren't necessary but perhaps the same goes for multi piston brakes. What are you trying to clarify here for us? I see a performance gains that have multiple viable paths. Going dual brakes has pros in terms of heat dissipation and wear/tear. The costs are pretty reasonable too.


My DNM USD-8 fork that has two rotor mounts was $400
The dual rotor mounted front hub was $39
The dual hydraulic brake from Tektro was $180.

Regards,
Al

 

[Chalo]

If maximum heat dispersion is the measure of braking superiority, then rim brakes win-- no contest.

Remember that a $40 disc brake has exactly the same maximum heat dispersion from the rotor as a $300 disc brake with the same size rotor. But if you try them, you'll know their performance isn't remotely similar. There are a lot of other factors involved. Twin rotors don't address any of those other factors-- but they do add weight and complexity and make the wheel weaker, while dramatically diminishing your choices of equipment.

 

[loysius]

If maximum heat dispersion is the measure of braking superiority, then rim brakes win-- no contest.

Remember that a $40 disc brake has exactly the same maximum heat dispersion from the rotor as a $300 disc brake with the same size rotor. But if you try them, you'll know their performance isn't remotely similar. There are a lot of other factors involved. Twin rotors don't address any of those other factors-- but they do add weight and complexity and make the wheel weaker, while dramatically diminishing your choices of equipment.

The heat dispersion spread is significantly better with dual brakes, the braking performance is dependent upon size of the rotor. The same thing goes right back at you, if all you care about is performance braking then rim brakes win.

Diminishes my choices of equipment how? I can still run just 1 brake caliper.. or I can run two like I'm doing... or I can put a different front wheel in for dirt cheap if I buy a prebuilt wheel which is standard with a 1 rotor mount hub. A bigger limit to my choices would be spending a ton of money on something insignificant and not having enough for other equipment. This tektro dual brake was already inline with my build and is not an insignificant brake that won't be able to stop my bike. The front fork I got was already cost effective because of it's performance/quality considering it's low cost. All I had to do was buy the $39 hub which wasn't more expensive than a regular front hub to get this build to work. I don't know what relevance a $40 brake's stopping ability vs what a high end system has but these twin hydraulic brakes won't have issues stopping the bike.

Regards,
Al

 

[MadRhino]

First, heat dissipation doesn't rely on a math formula, but on actual heat measurement. Every rotor has a different design and weight, even thickness is not the same with every brand. Brake pad surface and caliper design are also a major factor. There are just too many variables. What I know by actual measurements, is that my -550g MT-7 calipers are cooler than those bricks on a Suzuki GSX 1000 after the same 10 miles city ride (that I completed well ahead by the way)

2nd, braking power is not an issue since almost all brakes do have enough power to lock the wheel. Average braking distance achieved is the performance criteria. It does rely on modulation precision, and efficiency variation through all the range of surfaces and riding conditions. Using various brake systems on equal surface and riding conditions, will result in significant differences in braking distance achieved, half not being uncommon on one specific surface and 20% on average various surfaces test.

 

[nutnspecial]

I just finally put hydros on my ride and will prob never look back. Auto adjust, set and forget 'em. Mine are only 180/160 formula c1's for 100$ and I'm pleased as sh!t compared to anything else.

My gvw is about 240lbs. If nothing else for me hydro is about modulation and power available. I'm all for dual rotors when needed if they come close to the most expensive in performance, and beat them in price.