BigRock carbon crankset with 24mm titanium spindle

[kubackje]

Can you please give some info about axle length? What is your bike's bb total width? I'm a bit worried with my 91mm total, and there is no info about max bb width on Ali.

Sorry I can't it's already installed. But it's plenty long, I had to use some spacers on each side. It's few mm longer then Magene pes505 I've used before which was very tight fit on my of bb86

[kilka]

Well, you can, I'm asking about bb width and it can be measured with cranks installed, however regarding the fact that Magene PES is 90.5 mm wide, and those cranks are a bit wider, I'll try them. Thanks for your info!

[kubackje]

Well, you can, I'm asking about bb width and it can be measured with cranks installed, however regarding the fact that Magene PES is 90.5 mm wide, and those cranks are a bit wider, I'll try them. Thanks for your info!

Well I can't as I'm out of home for 2 weeks and only have my gravel bike with me 😂

[ice29]

I am out of town (away from bikes) for a few week so can’t check, but thinking about going smaller chainrings for my climbing Aethos (that runs the Bigrock crankset). Do you think the crank can take the Praxis spider?
https://www.bike24.com/p2729752.html
Or are there any Chinese solutions with 48/32 rings?

[Yunglord]

I am out of town (away from bikes) for a few week so can’t check, but thinking about going smaller chainrings for my climbing Aethos (that runs the Bigrock crankset). Do you think the crank can take the Praxis spider?
https://www.bike24.com/p2729752.html
Or are there any Chinese solutions with 48/32 rings?

Hey Ice,

Check out Stone they make what you are looking for.

46-32T 132g
48-33T 153g

[Yunglord]

I've now done about 1200km on the cranks and they are solid/crisp shifting and with the Ultegra rings / 160mm arms around 580g on my scale.

Have not noticed extra flex compared to the Ultegra r8100 they replaced.

Would recommend if you can buy with coupons on Ali.

[ice29]

I see a strange behavior with my Bigrock crankset, in Aethos frame and new Ultegra BSA BB…
When I push the left crankarm with spindle in (with the preload adjuster screwed all the way in), it is pretty stiff in the frame, it turns but not so smoothly… As you can see in the picture, I can turn the crank to point upwards and it will not fall down on its own… I tried with or without spacers, the same behavior. Also pushing the crank with spindle in is very hard.
No issues with normal Ultegra crankset, that spins freely, goes in easily etc.

Also how many spacers have you used with Shimano BB? I put the thicker black one on the drive side (this way I get the same chainline as with Ultegra crankset, as I don’t have to adjust the FD), the thinner black on the non-drive side, but when I tighten the crankset the preload adjuster won’t move…

[Yunglord]

I see a strange behavior with my Bigrock crankset, in Aethos frame and new Ultegra BSA BB…
When I push the left crankarm with spindle in (with the preload adjuster screwed all the way in), it is pretty stiff in the frame, it turns but not so smoothly… As you can see in the picture, I can turn the crank to point upwards and it will not fall down on its own… I tried with or without spacers, the same behavior. Also pushing the crank with spindle in is very hard.
No issues with normal Ultegra crankset, that spins freely, goes in easily etc.

Also how many spacers have you used with Shimano BB? I put the thicker black one on the drive side (this way I get the same chainline as with Ultegra crankset, as I don’t have to adjust the FD), the thinner black on the non-drive side, but when I tighten the crankset the preload adjuster won’t move…

No spacers on either side / No adjusting to do either with front FD same shifting as previously with the Ultegra crankset.

[ice29]

No spacers on either side / No adjusting to do either with front FD same shifting as previously with the Ultegra crankset.

Interesting! I thought the slack is too much without the spacers, but will try without them, or try washer-style spacers that should not be so draggy… but I have a feeling the spindle is just tiny bit bigger than the shimano one (I have seen that Rotor 24mm spindles were the same, very hard to push through shimano BBs)

Edit: without any spacers I have to turn the preload ring a lot, but with a spacer on the drive-side it's fine, also spins fine. So the spindle is a tiny bit thicker, but it does not matter really...

[awinner]

anyone know what the chainline is on these cranks?

[JustinFox]

No spacers on either side / No adjusting to do either with front FD same shifting as previously with the Ultegra crankset.

Yup same here (installed on a Tarmac SL8). No spacers, re-used the Ultegra chainrings and no adjustment needed at all.

Packaging was good, not a fan of the graphics but couldn't bring myself to sand them off (just yet). Carbon weave looks great. Spider is plain and simple and would have been much nicer if it was a decorative spider that matches the look of the Shimano rings.

As some have mentioned, no instructions. I torqued the 3 bolts to 6.5nm (please let me know if this is too much, or too little).

[rcwsr]

Interesting! I thought the slack is too much without the spacers, but will try without them, or try washer-style spacers that should not be so draggy… but I have a feeling the spindle is just tiny bit bigger than the shimano one (I have seen that Rotor 24mm spindles were the same, very hard to push through shimano BBs)

Edit: without any spacers I have to turn the preload ring a lot, but with a spacer on the drive-side it's fine, also spins fine. So the spindle is a tiny bit thicker, but it does not matter really...

I have a similar issue on an ultegra bsa bb. If I don’t use spacers on DS it spins ok with preload spacer taking up the slack, but the chain ends up too close to the inside side of the FD cage. If I put a spacer or 2 on DS then chain is in a good place but the bearings seem to bind up and it doesn’t spin very well. I think it’s because the DS crank can’t reach end of splines when spacers are installed and torqing it up just makes it tight against the BB. Gave up and put ultegra back on for now

[geramonta]

Has anyone taken apart the spider? I need to know how much it weighs and if I replace it with a potentiometer, how much weight that would add. I'm considering whether to use a spider potentiometer or pedal potentiometers.

[averagejoe101]

I have a similar issue on an ultegra bsa bb. If I don’t use spacers on DS it spins ok with preload spacer taking up the slack, but the chain ends up too close to the inside side of the FD cage. If I put a spacer or 2 on DS then chain is in a good place but the bearings seem to bind up and it doesn’t spin very well. I think it’s because the DS crank can’t reach end of splines when spacers are installed and torqing it up just makes it tight against the BB. Gave up and put ultegra back on for now

Exactly the same issue I was trying to resolve yesterday. My main reason for tinkering was to try to eliminate intermittent outboard chain drops with an Ultegra 12sp FD w/Pass Quest chainrings & Xcadey PM on a Speeder SC-R55.

The FD's limit is maxed out and still tries to push the chain too far at least once or twice a ride, which is significantly more than I feel is acceptable. 3mm & 2mm - shifts on point, but completely binds up at torque. 1mm DS torques down properly with the ability to adjust preload, but it's then back to the same issue. Having said that, in the bike stand, you can bang the chain up and down no worries, and only around 1-2 times will the chain either drop or ride the teeth before popping into gear. Take it out on the road and it's roulette. For the most part, it's been fine, and the chain will jump back on after a few pedal strokes. However, it's not without a few cursory scratches to the cranks.

I've not got around to trying it yet, but my next port of call will be to try to remove the preload from the equation and attempt to use spacers to load and shift the crankset over into a decent chainline. Wonky Q factor or not, I'd rather not have the chain keep dropping mid-ride.

[Tpower59]

Would this crankset work with Passquest AXS chainrings ?