Modifying SRAM spider

[jefenger]

Turns out you can mount Praxis 48/32t chainrings on SRAM 110BCD cranks with just a bit of filing. I did modified a non-hidden bolt spider. This should work for hidden bolt as well, but YMMW.

Praxis sells their 48/32t "for Praxis cranks only." I bought a set with the intention of mounting them to my SRAM cranks. Once the chainrings arrived, I realized why they won't fit. The Praxis spider is machined so that it can bolt to the small chainring without interfering with the chain. After comparing the Praxis spider to my SRAM spider, realized I could get it to work. After bit of grinding and filing, everything lines up.

[mhespenheide]

Very cool. Thanks for the idea, I might have to try it myself at some point.

[ultraman6970]

Ingenuity at its best.!!!

[NHAero]

I had to do some filing IIRC to get a 46T TA chainring to fit a Campy Record 11 compact crankset. And also to fit some Shimano MTB chainrings on a SRAM spider when doing the Mark McM hack for my Litespeed. When confronted with an interference, it's always worth looking very carefully, as you have done, to see if minor tweaks will let the bits fit together. It's annoying that manufacturers in some cases are making these items ever so slightly different so they won't be interchangeable. I get it that Praxis has gotten a 32T to fit where the next smallest compact 110 BCD ring is a TA 33T.

Thanks for posting.

[dddd]

I would remind everyone that the stress borne by the now-removed metal exists near-equally no matter which ring is being used.
You wouldn't want to suddenly lose drive while sprinting in the big ring is what I am saying.

The Praxis spider tabs would appear to have a different shape for a reason.

In all cases, when the end-used removes metal, they may be the first to test the result, since the manufacturer sure hasn't.
Lightweight parts are lightweight because practically ALL superfluous material has been removed. Removing more is going to change the rated load before failure and the number of cycles to failure.

[hollowgram5]

I had a buddy with a lathe cut back the relief for me on my spider. Have yet to buy to gs and mount it up, but it worked! Glad to see this done by someone else!

[hokoman]

Engin sells an adapter for SRAM cranks... Not sure if this is the same thing.

[hollowgram5]

Originally Posted by hokoman

Engin sells an adapter for SRAM cranks... Not sure if this is the same thing.

His is slightly different. It is 110/74bcd (I think), so you can use smaller than a 32t and adjusts the chainline for disc wheels.

[jefenger]

Originally Posted by hollowgram5

I had a buddy with a lathe cut back the relief for me on my spider. Have yet to buy to gs and mount it up, but it worked! Glad to see this done by someone else!

Awesome, glad to see there are others out there who saw the same problem/solution. Will you also be running a 32t or is there something smaller out there that works?

Originally Posted by NHAero

I had to do some filing IIRC to get a 46T TA chainring to fit a Campy Record 11 compact crankset. And also to fit some Shimano MTB chainrings on a SRAM spider when doing the Mark McM hack for my Litespeed. When confronted with an interference, it's always worth looking very carefully, as you have done, to see if minor tweaks will let the bits fit together. It's annoying that manufacturers in some cases are making these items ever so slightly different so they won't be interchangeable. I get it that Praxis has gotten a 32T to fit where the next smallest compact 110 BCD ring is a TA 33T.

Thanks for posting.

Agreed. It would've been nice if the Praxis spider mounted up to SRAM, but of course the spider cutouts are different shapes to account for the shapes of the crank arms...

[jtbadge]

Is this for a power meter crank, or something? I guess I don't understand the motivation behind these mods when you could just run the Praxis crank. They're everywhere and not expensive.

[hollowgram5]

Originally Posted by jefenger

Awesome, glad to see there are others out there who saw the same problem/solution. Will you also be running a 32t or is there something smaller out there that works?



Agreed. It would've been nice if the Praxis spider mounted up to SRAM, but of course the spider cutouts are different shapes to account for the shapes of the crank arms...

Just for a 32T. If I wanted to go smaller, if just buy the aforementioned Engine spider.

Originally Posted by jtbadge

Is this for a power meter crank, or something? I guess I don't understand the motivation behind these mods when you could just run the Praxis crank. They're everywhere and not expensive.

Nah. Mine wasn't for a PM, but I'm guessing with the lathe we could replicate if we wanted. I did it because I had the spider, I had the crankset+bb, and I didn't want to spend the time or money searching out a praxis crankset with that specific spider configuration and buy the praxis BB to go with. And my friend has a lathe, so it cost me lunch.

[jefenger]

Originally Posted by hollowgram5

Mine wasn't for a PM, but I'm guessing with the lathe we could replicate if we wanted. I did it because I had the spider, I had the crankset+bb, and I didn't want to spend the time or money searching out a praxis crankset with that specific spider configuration and buy the praxis BB to go with. And my friend has a lathe, so it cost me lunch.

Similar for me - I had the crankset already for a build, but last minute got the Praxis rings and spider for around $40 shipped. And, since I'm spending the majority of my time indoors these days, doing the mod was more interesting to me than buying the Praxis crankarms.

[ergott]

Originally Posted by dddd

I would remind everyone that the stress borne by the now-removed metal exists near-equally no matter which ring is being used.
You wouldn't want to suddenly lose drive while sprinting in the big ring is what I am saying.

The Praxis spider tabs would appear to have a different shape for a reason.

In all cases, when the end-used removes metal, they may be the first to test the result, since the manufacturer sure hasn't.
Lightweight parts are lightweight because practically ALL superfluous material has been removed. Removing more is going to change the rated load before failure and the number of cycles to failure.

Agreed. The Praxis tabs are noticeably wider which compensates for the material removed elsewhere. I've seen tabs fail on cranks before, I wouldn't go anywhere near that with a high torque situation like small rings which will most likely be paired with a large cog out back.