YonathanZ

And that heat could cause the tire to explode?

invisiblehand

Based on what some tandem folks have said, you can indeed get blowouts or other wheel/tire failures.

We personally have not had the problem since our triplet has an Arai drum brake as a drag brake.

energyandair

I've avoided the situation myself but my understanding is that tire problems are possible and braking problems are likely. Excessive heat is not a friend of brakes and bicycle rim brakes are not designed for extreme heat.

In general, I would not expect a problem for normal round town riding but having to brake quickly from over 60kph on a steep downslope or long term continuous braking to avoid exceeding safe cornering speed on a steep twisty downslope are things I would plan to avoid and the limits I would set with small wheels in hot weather would be more conservative than with large wheels in cool weather.

Amt0571

So far I've not had any problem with any of my bikes braking from high speeds, even in 10km+ downhills.

I think what causes problems is not breaking itself but dragging the brakes during a long time. I think it's preferable to attain a higher speed without braking and then having to brake harder than dragging the brakes continuously.

Anyway, tire blowouts tend to occur in tandems and in high pressure road tires. I think they are highly unlikely on a folding bike.

Azreal911

Going downhill really fast doesn't stress the frame much at all just alot of guts. That's just gravity pulling the entire bike with it evenly, pretty much very little stress. But when you get a 500+watt pushing/pulling against your weight to get it moving from a dead stop, that is a entirely different set of factors being put on your bike.

What I was mainly saying don't buy those kits they sell that put it on the front wheel. That's when it is really too stressful! the rear wheel is fine because there are more points on your frame to distribute the force of a 1000+watt engine.

if you don't believe me then you might want to read up on this:
https://www.electricbike.com/torque-arm/

and

Endless-sphere.com ? View topic - Catastrophic front fork failure / BMC front wheel drive

some of those reads are scary like this quote:
"We had a friend in our group have his suspension fork bust high next to the steering tube landing him in the intensive care unit with a critical head injury"


they had front forks FAILED on them and they suggest 500watts and up you should reinforce them with some of their suggestions. I don't think you want the front fork to fail while you are in traffic with idiot drivers being so close to you.

didn't know Israel drivers were aggresive at least you should be able to zip past the cars faster in heavy traffic good luck!

jur

Get Coolstop salmon brake pads. The single best upgrade you can make. Turn mediocre brakes into excellent ones.

Then make sure the V-brake arms are a nice rigid type. Flexy ones will olso ruin good braking.

invisiblehand

We'd want to ask a real engineer, but off the top of my head, you have to convert the same amount of downward velocity (kinetic energy) to heat to slow you down. I'd be surprised if there was a meaningful difference between the two.

Amt0571

The air brakes you more the faster you go. It's exponential. Also, the faster airflow cools the rims.

I still think that dragging the brakes is not a good idea.

YonathanZ

Hey, are these the ones?
Amazon.com: Kool Stop Bicycle Brake Pads

They have two types: Ultegra / Dura-Ace, and Continental. Which one do I need?

These are my v-brakes by the way:
TEKTRO BRAKE SYSTEMS

For now I'll keep this bike as it is but will only upgrade the brakes, because they're ****ty even at 20kmph.

Thanks.

jur

You need mtb pads for v-brakes. This ebay number shows: 191222388339

It will work out cheaper if you have refillable pads:
131507799601

YonathanZ

What are refillable pads? By the way, shipping the replacement pads costs $15, and the other ones are $10 to ship, so the "normal" option is cheaper. BTW, do I buy the same pads for both front and rear brakes?

EDIT: I just looked at Kool Stop's compounds list in an attempt to figure out whether I need a dual-compound or a salmon type pads. I should mention that I only ride in dry conditions. It's a dry country anyway, it barely rains for 3 weeks a year here in Israel.

Anyway, apparently, they have another compound called "Electric" which, you guessed, is for electric bikes that go relatively higher speeds. It doesn't say what weather conditions they're suited for, but I'll bet that dry conditions are first on the list.

EDIT 2: If I buy the pads only, without the metal screw thingy, will I be able to attach them to my current brakes?

jur

Refillable pad holders are holders that the pad slides out of, allowing you to slide new pads into the holder. They are held in with a little locking pin. I won't be able to say what type you have, but likely they are not refillable. Have a close look at them, you'll be able to tell by examining them. Same pads front and back.

Poor braking can be several things, poor cables, poor setup and poor pad compound.

From your comments, you lack knowledge, and since brakes are a safety critical item, you either need to read up at park-tool.com and sheldonbrown.com or you need to let a bike shop do it for you.

YonathanZ

I've had three shops try to fix the brakes, and they all failed. The first played with the screws in an attempt to have the rubber compound closer to the rim. So one arm of the brake is not parallel with the ground anymore.

Another shop had the cables replaced and then tightened them as needed. The wheel still squeaked. Then a third shop mechanic acted as if he was doing me a favor for free and just had the front wheel reinstalled, because it wasn't centered at all. That actually helped but I still get annoying, loud squeaking sounds when I brake or just move the bike around.

jur

I hear you. Sometimes it is not that easy to find the sort of quality mechanic such as some of the lbs guys posting here.

Post a pic of the front brake, then we'll go from there.

fietsbob

most of the E bike stuff is made by some Chinese company , in the kind of price you are comfortable paying.


you wish to get a cheap motor bike without paying the higher risk-priced insurance .. Good luck with that ..

YonathanZ

jur

I can't see the brake pad, so can't tell if they are the replaceable pad holder type.

jur

In the mean time, see if you can source some of the e-bike pad compound. I am guessing that compound will be higher temperature rated.

energyandair

The brake should be parallel to the rim, not to the ground.

Squeaking can be hard to get rid of and can come and go. Failure to eliminate it first time does not necessarily mean a bad mechanic

energyandair

It doesn't affect much but the rubber boot at the end of the cable appears to be back to front. If the mechanic installed it that way I would see it as a bad sign.

The photo doesn't show the whole picture but the brake cable routing looks odd to me.

YonathanZ

Couldn't find them on eBay. On Amazon, shipping to Israel is too expensive ($20 or so) for such a small, cheap item
.
Thanks, that's what I meant.

It's not just the sound it makes - the brakes just don't do their job well, especially the front one, which was serviced the most. A bad front brake is rather unsafe.

It's just cosmetic, right?

Most of the cables you see are electric cables. The brake cable routing is actually fairly "standard", as far as I know.
The front brake cable goes behind the headlight and then straight up to the lever, but it does look like a mess in this particular photo I posted.

jur

These are the learning resources I mentioned before:

Adjusting Direct-pull Cantilever Bicycle Brakes ("V-Brakes ®")
Bicycle Rim Brakes
Park Tool Co. » ParkTool Blog » Linear Pull Brake Service (V-brake style)

Familiarise yourself thoroughly with the brake adjustment issues, since especially for your case is such a safety crititcal issue.

If you can't get e-bike compound, settle for black. You don't need salmon. It does not need to be Koolstop either, there are other good pad makers. The stuff you get with cheap bikes made in China will have the very cheapest pads, often with very poor braking quality.

YonathanZ

The pads I have installed now are made by Tektro. Are they considered cheap ones?
I'll have a look at the learning resources on the weekend.
I've done some reading about the different compounds by KS, and it seems that the consensus is that Salmon are better even in dry conditions, but they get worn faster.

I was able to find an eBay seller that has the dual compound ones, and 2 pairs + shipping would cost me $35, which is a fair price. Should I go for it?

jur

Tektro ones should be good. That's worrying.

SesameCrunch

I've had two blow outs on 20" (406) tires coming down long mountain descents. It's not fun 'cause you're going pretty fast on downhills. On one blowout coming down a 2,000 ft descent with a recumbent bike, the front tire blew, dragged on the ground, rear end came over the top and I was thrown over the handlebars. Good thing I had the presence of mind to tuck and roll. I was going about 22mph and didn't get any injuries even though the bike landed on top of me.

I'm only riding down big hills with disc brakes now. Lesson learned....