Search found 5748 matches

by Chalo
Jan 18, 2018 12:06 pm
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

Buk___ wrote:
Jan 18, 2018 3:16 am
[...]well below the 480Mpa fatigue limit of normalised ChroMoly.
That's close to the yield stress of normalized 4130, so the fatigue limit would be not much more than half that.
by Chalo
Jan 18, 2018 11:54 am
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

I've personally never felt like pedaling related forces were significant compared to riding impact related forces. Right. Potholes and even little bumps can have much higher instantaneous peaks (even if the durations are short), and hard braking winds up a frame much more than hard pedaling. Make t...
by Chalo
Jan 18, 2018 2:19 am
Forum: E-Bike Non-hub Motor Drives
Topic: Project Dauntless - My Tanget build
Replies: 27
Views: 709

Re: Project Dauntless - My Tanget build

Previous needle roller clutch freehubs (Shimano Silent Clutch hubs and Winners hubs) were regarded as less robust and reliable (with pedal power only) than ratchet freehubs.
by Chalo
Jan 18, 2018 2:12 am
Forum: E-Bike Technical
Topic: Repair to bent rim. Advice and help pls
Replies: 17
Views: 175

Re: Repair to bent rim. Advice and help pls

Chukker is a good rim. At least it was when they bought it. This all comes across as very unfortunate.
by Chalo
Jan 18, 2018 1:22 am
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

So you are saying that no steel bicycle frames are built to withstand 250MPa stresses? Do you mean built to withstand foreseeable working stresses while remaining under 250MPa throughout? Remember all steels aren't equal in strength, and their fatigue limits are a function of their yield stresses. ...
by Chalo
Jan 17, 2018 9:00 pm
Forum: E-Bike Technical
Topic: Repair to bent rim. Advice and help pls
Replies: 17
Views: 175

Re: Repair to bent rim. Advice and help pls

Yikes, that's really bad. I have built some wheels on rims that bad. I unlaced them, sent them back and started over. Can you share with us what kind of rim they used? The rim is not necessarily the problem, but... it probably is. It would take a truly exceptional amount of incompetence to get a res...
by Chalo
Jan 17, 2018 8:51 pm
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

Every time I mention "Al has no fatigue limit", you say: "All structural metals work harden; all of them fatigue." which is a fundamental mis-statement of the facts. You know that steel work hardens. It's why we cold forge things. And we all know that steel fatigues because we see bikes and other o...
by Chalo
Jan 17, 2018 5:57 pm
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

It's like you have learned an engineering concept, but failed to understand its implications or importance in real world engineering. Oh Chalo. I greatly respect your advice about bikes; but please don't think your 10 years as a bike mechanic, and un-cited, anecdotal witticisms make you qualified. ...
by Chalo
Jan 17, 2018 2:51 pm
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

Don't get hung up on material. One important structural limitation of aluminium alloys is their fatigue strength. Unlike steels, aluminium alloys have no well-defined fatigue limit, meaning that fatigue failure eventually occurs, under even very small cyclic loadings. Engineers must assess applicat...
by Chalo
Jan 16, 2018 8:12 pm
Forum: E-Bike Non-hub Motor Drives
Topic: New "TSDZ2 Torque Sensor Central Motor"
Replies: 1391
Views: 99582

Re: New "TSDZ2 Torque Sensor Central Motor"

I'm especially curious about the CSK one-way clutch failures. My impression is that the CSK clutch only engages to transmit pedal power, and does not have to transmit motor power. Is this correct? I have been planning to try one of these TSDZ2 units, but I have to be able to pedal strongly without b...
by Chalo
Jan 16, 2018 8:03 pm
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

e-beach wrote:
Jan 16, 2018 7:45 pm
So today, I was looking through my local Craigslist and their is mostly junk for sale in the price range I was looking to pay, $150ish because that is probably the cost of getting it welded around here.
http://www.nashbar.com/bikes/Product2_1 ... 0003472_-1
by Chalo
Jan 16, 2018 7:37 pm
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

Do you regularly exert 1300N forces to your pedals, whilst cranking the bike over at 7.5 deg to the direction of the force? I don't. I stand up to climb, yes. In my case, that's over 1500N if I'm not pulling on the bars to increase pedal force further. And when I'm standing to climb, I rock the bik...
by Chalo
Jan 16, 2018 5:27 pm
Forum: E-Bike General Discussion
Topic: The winner is . Not what you think
Replies: 17
Views: 394

Re: The winner is . Not what you think

And with time those cars will get smaller, lighter and more efficient (following the same trend they are now.) I don't see such a trend. I know that in 1980, you could buy a car that weighed under a ton, carried four adults, and got 50 mpg. Today, the same car has put on something like 75% more wei...
by Chalo
Jan 16, 2018 1:38 pm
Forum: E-Bike General Discussion
Topic: Marin County, San Francisco Bay Area?
Replies: 11
Views: 116

Re: Marin County, San Francisco Bay Area?

Thank the unregistered-motorcycles-with-pedals dicks whenever e-bikes are banished from public infrastructure. I don't think that's the problem here. I've ridden extensively on the open space trails over the last year and I think I've only seen maybe two other ebikes, and they were Bosch drives. Th...
by Chalo
Jan 16, 2018 1:28 pm
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

All structural metals work harden; all of them fatigue. One difference that steel has compared to aluminum, is that after repeated loads, aluminum will fatigue. Steel has an indefinite fatigue life, which means it has enough strength to withstand repeated load cycles, and hence, it lasts longer, or...
by Chalo
Jan 16, 2018 3:14 am
Forum: E-Bike General Discussion
Topic: The winner is . Not what you think
Replies: 17
Views: 394

Re: The winner is . Not what you think

It always amazes me when I think to myself that this problem didn't even exist a short 120 years ago, travel by horse and buggy worked pretty good didn't it? When bicycles arose, there was much outrage because they went too fast. I'm sure there were a few hooligans and jackasses who made that impre...
by Chalo
Jan 16, 2018 3:04 am
Forum: E-Bike General Discussion
Topic: Hubmotor with cassette?
Replies: 2
Views: 73

Re: Hubmotor with cassette?

That hub should be compatible with Shimano, Sunrace, or SRAM cassettes with 8, 9, or 10 speeds.
by Chalo
Jan 16, 2018 3:02 am
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

All structural metals work harden; all of them fatigue. I've never put more miles or years on a bike than my 1991 Cannondale aluminum MTB (with all-aluminum fork to boot), which is still in fine shape. I think a steel frame would have to have been twice as heavy to have lasted as long. (But at twice...
by Chalo
Jan 16, 2018 1:17 am
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 75
Views: 804

Re: Potential Catastrophic Frame Failer Averted ….sort of.

Steel suffers hydrogen embrittlement, deep corrosion, and other critical failures issues that aluminum doesn't. Steel is a little easier to build into a reliable bike frame-- but that doesn't make every steel frame reliable, nor every aluminum frame unreliable. For what it's worth, I'd take a five p...
by Chalo
Jan 16, 2018 1:08 am
Forum: E-Bike General Discussion
Topic: Marin County, San Francisco Bay Area?
Replies: 11
Views: 116

Re: Marin County, San Francisco Bay Area?

Thank the unregistered-motorcycles-with-pedals dicks whenever e-bikes are banished from public infrastructure.

Plates and insurance go a long way towards keeping the peace. They allow us to take the high ground.
by Chalo
Jan 16, 2018 1:02 am
Forum: E-Bike Technical
Topic: BBSHD on Klein Palomino Keeps Breaking Rear Cassette
Replies: 13
Views: 170

Re: BBSHD on Klein Palomino Keeps Breaking Rear Cassette

I use a BBS02, and all I have to show in terms of parts destruction is one chain that got a link peened stiff due to shifting under power (there's no shift sensor on my bike). I swapped a chain and cassette at a little over 600 miles because enough wear was indicated to be of concern. That said, I u...
by Chalo
Jan 16, 2018 12:29 am
Forum: E-Bike General Discussion
Topic: The winner is . Not what you think
Replies: 17
Views: 394

Re: The winner is . Not what you think

More than anything, governments should dramatically raise the taxes on gasoline and diesel to partially offset the external damages caused by using petroleum for propulsion. Don't worry about lost revenues from people moving in the right direction. Make them up by taking it out of people who don't. ...
by Chalo
Jan 15, 2018 4:51 pm
Forum: General Discussion
Topic: Alternative current
Replies: 28
Views: 233

Re: Alternative current

A simple way to limit the power would be to use a power supply that doesn't produce more than the amp and speakers consume at their maximum rating. I made a nominally 40W portable amp and ran it with ten AA NiMH batteries. They probably could have produced more than 40W into a resistive load, but in...
by Chalo
Jan 15, 2018 4:19 pm
Forum: E-Bike Technical
Topic: Repair to bent rim. Advice and help pls
Replies: 17
Views: 175

Re: Repair to bent rim. Advice and help pls

You didn't say whether you'd put some miles on the wheel between picking it up from the bike shop and it becoming loose. If you had done so, then the wheel loosening might be more a matter of bad hub design (holes too big, flanges too close together) and inappropriate component choice than of the bi...
by Chalo
Jan 15, 2018 1:56 am
Forum: E-Bike Technical
Topic: Repair to bent rim. Advice and help pls
Replies: 17
Views: 175

Re: Repair to bent rim. Advice and help pls

Take the wheel back and demand that they tighten the spokes to 1000 newtons. That's the least they can do after charging you full price. My shop charges USD$50 plus the cost of spokes and rim. The wheel will always be true, round, centered over the hub, stress relieved, and tightened to at least 100...