e-Bikes – Let’s talk

[jnva]

Hozn, you are probably right about the tension imbalance. I should probably pay more attention to that.

[hozn]

Huh, ok. Well I am surprised by the breaking but the Strong sounds like the way to go. I have had the opposite experience, breaking straight gauge spokes — but those have always been factory-built wheels, so not apples-to-apples.

Maybe confirm that the spoke tension is appropriately high? Assuming normal rim, should be 120-130kgf. You could use the iPhone spoke tensioner app to check if you don’t have a tension meter. (Or you can borrow my tension meter!)

[jnva]

Let me clarify, it’s not the butted spokes that are breaking, it’s the straight ones. As they break, I’m replacing them with the sapim butted spokes. And they aren’t breaking in the same place, some break at the nipple end and some at the rim.
Edit, I mean hub not rim.

[jnva]

iPhone spoke tensioner! Must download now!!!

[jabberwocky]

@hozn 73082 wrote:

I have had the opposite experience, breaking straight gauge spokes — but those have always been factory-built wheels, so not apples-to-apples.

I was actually surprised to be breaking the CX-rays so much, but cie la vie. My dirt jumper/urban wheels are Mavic 729s on champion spokes and they’ve been the most bombproof wheels I’ve ever owned. And thats a bike that spent several years being ridden off loading docks, down stairs and occasionally casing the landing on dirt jumps. I don’t think they’ve ever even seen a truing stand after the initial build.

[jabberwocky]

@jnva 73084 wrote:

Let me clarify, it’s not the butted spokes that are breaking, it’s the straight ones. As they break, I’m replacing them with the sapim butted spokes. And they aren’t breaking in the same place, some break at the nipple end and some at the rim.
Edit, I mean hub not rim.

Factory wheels? If so, Hozn is probably right that its the build and not necessarily the spokes.

[jnva]

Alex DM 24 rim with sapim straight spokes was built for me, but I think it has a lot to do with my riding style. I sort of feel like if I don’t break something, I’m not having enough fun!

[hozn]

@jnva 73085 wrote:

iPhone spoke tensioner! Must download now!!!

Yeah, the developer, Doug, is a friend (and coworker) of mine. The science behind the app (using freq to determine tension) is good, but I know that the challenges are in the signal processing — isolating the frequency (so helps to use it in a relatively quiet place). Also factoring in the butting of the spoke when measuring the length can be a little tricky. For straight-gauge naive measurements work, but he was mentioning that on the bitted spokes he has found the effective length for calculations seems to be closer to halfway down the start of the taper (e.g. 2.0->1.8, or 2.0->2.3 in your case) near the nipple (as opposed to right to the nipple) Anyway, I am sure he will be more than happy to help by email if you have any trouble or general questions. Anyway, I do not have an iPhone, so haven’t been able to use it myself. I would like to, since there are aspects of this that would be much nicer than the deflections based tension meter that I use (e.g. keeping track of all my tensions to show me average tension at a glance and show which spokes are deviating the most).

[americancyclo]

sliding around this morning, and then seeing an e-bike a work in the rack, i wondered:

How do ebikes handle this weather?

[jnva]

Awesomely. I had a great time in the snow this morning!

[jnva]

[ATTACH]4399[/ATTACH]

On the custis, on top of one of the sister hills. My rear brake cable snapped but I still had regen braking!

[83b]

If you’re using a front hub motor it’s like having two wheel drive! But you do have to be careful on a few fronts. First, cold batteries are going to put out less power and provide less range. Second, even with reduced power it can be pretty easy to spin the front wheel during a snowy start, which results in a really weird front-fishtail sort of effect.

You’re not at roughly 14th and H are you? I don’t imagine there are that many e-bikes out today.

[jnva]

I commute to near McPherson square. Near 15th and L. Roads were fine, just the custis and WOD were rough going.

[jnva]

@hozn 73109 wrote:

Yeah, the developer, Doug, is a friend (and coworker) of mine. The science behind the app (using freq to determine tension) is good, but I know that the challenges are in the signal processing — isolating the frequency (so helps to use it in a relatively quiet place). Also factoring in the butting of the spoke when measuring the length can be a little tricky. For straight-gauge naive measurements work, but he was mentioning that on the bitted spokes he has found the effective length for calculations seems to be closer to halfway down the start of the taper (e.g. 2.0->1.8, or 2.0->2.3 in your case) near the nipple (as opposed to right to the nipple) Anyway, I am sure he will be more than happy to help by email if you have any trouble or general questions. Anyway, I do not have an iPhone, so haven’t been able to use it myself. I would like to, since there are aspects of this that would be much nicer than the deflections based tension meter that I use (e.g. keeping track of all my tensions to show me average tension at a glance and show which spokes are deviating the most).

I downloaded the iphone app, will test it out this weekend and post results.

[MattAune]

I have a Park TM-1 you are welcome to borrow if you want to compare. I would be interested to see the results

[Author]

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