Disk brakes too strong? Tern Verge P10
 

Last year I bought Tern Verge p10.

Unfortunately, soon I had the accident in which I broke my right hand. The reason was, in unexpected situation I hit the brakes, the bike stopped immediately and I did not. Classic.

Just before the accident, my speed was about 17 kph, which I know because of Strava. I do not think it is very high.

This is my first bike with disc brakes, with only one other experience, so I am inexperienced as to how they should behave.

Should not they be more loose? On my previous bikes an accident like this would be much more difficult because the brakes were not so tight. I sometimes feel uncomfortable when the bike is rolling slowly 1-2kph - it feels too easy to completely stop.

My boss has a normal size cross bike with disc brakes, which I use occassionally during lunch breaks. Those brakes are not so immediate, too - I feel much more comfortable with controlling the braking power.

It was set this way by the shop that sold the bike, so if they got it wrong, I do not feel I can trust them.

Hydraulic discs are very powerful with good modulation. They should work well for you but you definitely have to relearn braking from older systems, especially if you're used to caliper road brakes. A light touch is all you need.

Classic user error.
I see that the Tern Verge p10 has IS standard brakes. That is post mount brakes on a rotor size adaptor. The smaller wheels will afford a significantly stronger braking force at a given rotor size due to the proportional relationship between the two. It would be tempting to go for a smaller rotor to reduce the leverage that could be exerted & this have a more spongy/ progressive system that would be easier to modulate.

What you don't get is a lower need for heat dissipation. A smaller rotor will overheat & fade sooner, greatly increasing the risk of failure when you need them the most.

The bright side here is the rotors on Tern's website for your bike look like some super light weight ones that couldn't absorb much of a heat load anyway. You might be ok with a smaller road bike specific rotor with more capacity than the OEM one you have. Something such as a Shimano IceTech. Some of them have riffled cooling fins, others have so much material they look almost solid. You would also need a new IS mount adaptor to accommodate the smaller rotor diameter.

I don't know that I'd make that trade. I'm just saying that based on what the website shows in the pictures, that such a thing could be done.

Yes. That is the one pitfall of lightweight two wheeled transport, especially small wheels, the center of mass is high and continues forward, as rapid deceleration occurs, so you tend to tip forward. An experienced rider would lean back when braking hard, but for normal riders, the reflex is to lean on the front bar, which exacerbates the weight transfer and the moment of inertia goes over the braking force.
As your recover, learn to lean back and actuate your rears first, without locking the wheel if possible, before hitting your fronts hard, and of course, learn to lean back quickly as a reflex to emergency hard braking.

It sounds like the brakes work fine, but the rider needs to modulate them properly to stop safely. Disc brakes are great because they work well even when they are wet, and they concentrate the braking force neat the axle. If you slam on the brakes in a moving car (without ABS), you lose control and slide, so you modulate the brakes. The same applies to bikes.

You just need to get used to the braking force and apply pressure accordingly. If you have any sort of modern car, likely it has the ability to lock up the brakes without much force but you don't worry about that as you're used to it.

To me, the more braking power the better.

go to a empty parking lot and practice stopping.

Out of interest, what rotor do they have. If you consider that a gravel bike fitted 27.5” tyres is fitted with 160mm rotors, with 20”, 160mm may seem oversized.

Looking a size ratio, 140mm rotor on a 20”rim has similar ration as a 203mm rotor on mtb 29er…

Another solution to have a softer braking is changing the disc brake pads to have less powerful ones.

Soft bake pads have a lot of power and wear fast, harder pads have less braking power and last longer.

I do not agree with this statement.

First, the TRP Spyre with 160mm disc I have on my Birdy Titanium are really OK and do not have much more power than the Ridea caliper on my Brompton. The rotor are TRP rotor but I do not know what brake pads were mounted by Pacific Cycles.

The Shimano Deore hydraulics of my Birdy III are much more powerful than the TRP Spyre with the same disc diameter of 160mm. The reason for this is the type of Shimano disc and brake pads chosen by Riese & Müller (rotor for only resin brake pads with Shimano resin pads, I think its G03S).

I have G04S semi-metal with Shimano XT Ice Tech rotor and these are much more progressive and require more power on the lever to obtain the same braking force.

Not quite... I run harder enduro pads and they brake better than soft organic pads. My enduro pads need a little warm up but they stop harder and longer than the soft organic that brake from cold but cannot handle the repeated hard brake and over heat...

As others said, it is about the technic (like with car although cars have abs because many drivers can not modulate). But if the mechanical advantages are not adequate (oversized brake) then, the braking out brake the tyres and the vehicle (car, bike etc.) goes into a skid.

Semi metal pads (on bike and car) operate at higher temperature than organic pads. they need to worm up, not more power, but more applications. Yes when you apply more power you will get them to to work but you will create more wear. If you wear to apply the brake lighty a bit earlier, the system will be "hot" and brake better.

When I raced, I used to do the warming lap left foot braking to make my metallic pads would work and once warm, no hard pedal, it was the same as cold organic. Same with my metallic pads in the rain, I clamp them a little as I start the ride to warm up and then, they brake well without excessive force and have good modulation.

What I mean is that resin pads brake immediately hard even with little power on the lever. Later on, indeed they do not resist as well to long braking like in downhill or/and an heavy bike.

But the problem here with this Tern is too much power when starting braking.

Therefore, I think that moving to semi-metalic is a solution with changing the rotor if the one mounted aren't made for semi-metalic pads.