Magene P515 PES Spider Powermeter

[ediryppah]

Does anyone know if the L/R balance is reliable? Thinking of getting a left side only assioma pro mx for my gravel bike, since the values I get on L/R from the P515 is almost always 50/50. But if the data is not good then I might reconsider.

[raisinberry777]

Does anyone know if the L/R balance is reliable? Thinking of getting a left side only assioma pro mx for my gravel bike, since the values I get on L/R from the P515 is almost always 50/50. But if the data is not good then I might reconsider.

No - no spider power meter can provide accurate L/R balance data - it is inherent in the design. Spider PMs do it by estimating from push and pull, but it doesn't truly know left from right.

[WestTown]

Just got a gravel bike with 1x GRX.

I have read that some use the P515/P505 and it works, but can someone explain to me what I need to know to make it work and what the consequences are?

Off the top of my head, I need to buy the PM crankset without chainrings and then get some special chainring that adjusts the chainline?
Can I achieve the same chainline position as stock GRX? If not, what's the difference?

If I currently have room for 48T chainring, is there a way to approximate what chainring size will fit? I'm OK with maxing out on 46T but 44T is a little limiting for certain conditions (keeping up with the fast riders with 2x systems on asphalt sections).

Also I guess Q-factor will be affected, but I can live with that if I go long axle pedals/MTB pedals and a couple washers.

How did it turn out for you? I also want to install a Grx 1x drivetrain and am currently looking for a suitable chainring. What did you use?

[cyruscycles]

No - no spider power meter can provide accurate L/R balance data - it is inherent in the design. Spider PMs do it by estimating from push and pull, but it doesn't truly know left from right.

Anecdotally, it seems to be accurate enough for me. I checked the balance and it said I had a significant discrepancy. When I focused on my pedaling style, I noticed it was totally right, and now I work on correcting it. Totally usable for what I think most people want balance readings for. I have a PES 505, and I picked a TEO Magene spider over the 715 pedal power meters for an upgrade. True L/R readings aren't worth it due to the inconvenience of adding another item to charge

As is, I have a bike computer, radar light, bike light, di2, a spider power meter, my bone conducting earbuds, my phone, my heart rate monitor, and my speed sensor to manage. I'm not adding another item to charge unless I absolutely need it

[Picograms]

Kind of a stupid question, but when you zero offset by pedaling backwards 5 times doesn't the fact that you apply pressure on the pedals messes up with the zeroing ?

For crank based PM's you are not supposed to mess with them while you perform a zero offset.

[ediryppah]

How did it turn out for you? I also want to install a Grx 1x drivetrain and am currently looking for a suitable chainring. What did you use?

I never got around to doing it, winter came fast. I'm currently considering just getting SPD power meter pedals instead, but we'll see.

Anyway, I don't have the answer but my take is this:

Chainring intended for 1x road should work.
The chainline will be affected, but to the better.
Problem is chainring clearance to the chainstay. If you're gonna be on 42T, probably not a problem. If you're planning to run 46-48T, probably a problem.
In any case, I'd buy some spacers for the spindle to have on hand, might be needed between the crank and BB regardless, but can also be used to adjust a little bit.

Example of Aliex listing with pictures where a Magene PM crank is used: https://www.aliexpress.com/item/1005009252104058.html?spm=a2g0o.productlist.main.4.4fd6371bTsebpe&aem_p4p_detail=202512020005401574748892120780000091180&algo_pvid=ca8d5c5a-3372-4415-8743-d3173df0cfa6&algo_exp_id=ca8d5c5a-3372-4415-8743-d3173df0cfa6-3&pdp_ext_f=%7B%22order%22%3A%2249%22%2C%22eval%22%3A%221%22%2C%22fromPage%22%3A%22search%22%7D&pdp_npi=6%40dis%21SEK%21290.69%21133.72%21%21%21212.06%2197.55%21%40210388c917646627401568198e72ef%2112000048481322098%21sea%21SE%21190294757%21X%211%210%21n_tag%3A-29919%3Bd%3Af670ceff%3Bm03_new_user%3A-29895&curPageLogUid=39WJeyvIHf8t&utparam-url=scene%3Asearch%7Cquery_from%3A%7Cx_object_id%3A1005009252104058%7C_p_origin_prod%3A&search_p4p_id=202512020005401574748892120780000091180_1

[themostaveragecyclist]

Anybody tried this on a Trek Domane SL6 Gen4. I have read about small clearance but wonder if that causes any problems. Especially when putting large power into the pedals.
This has T47 cranks but a 105 R7100 crankset with 175 mm arms

[Grumms]

Try contacting Magene directly to try and buy the shorter cranks. I don't think any other cranks fit the spider.

It's 55$ + 20$ of shipping, + customs. Not sure it's worth it.

[Uberflo]

As I read about region locks on Magene products: does this also apply on powermeters?

[Rebel_Yell]

As I read about region locks on Magene products: does this also apply on powermeters?

Mine has worked perfect since install 3 weeks ago.  Install and setup went great and has worked perfectly.

[amacal1]

Kind of a stupid question, but when you zero offset by pedaling backwards 5 times doesn't the fact that you apply pressure on the pedals messes up with the zeroing ?

For crank based PM's you are not supposed to mess with them while you perform a zero offset.

Not a stupid question at all, I've wondered the same thing. Most power meters and headunits that allow you to zero offset mention that you shouldn't even be clipped in. When I do it, I tend to do it by hand so I'm not clipped in. But, even still, I've found myself wondering if it "zeroes" while I'm still spinning it or if it zeros immediately after I stop spinning it, or what? I have no idea. If you find an answer, please share!

[oker_s]

Is it possible to rename the PM in the app?

[Picograms]

Managed to cross thread the big aluminum retaining bolt. Anyone knows how could get one easy/cheap from inside the  EU?

[00Garza]

It was $30 shipped to US to replace the faulty bolt on my P505. I'd think it would be similar.

[SaunaBiker55]

Managed to cross thread the big aluminum retaining bolt. Anyone knows how could get one easy/cheap from inside the  EU?

I was in a similar situation.  Put in a plastic shimano "bolt".  No issues with it at all