BigRock carbon crankset with 24mm titanium spindle

[warthog]

Got some coming. After 20 years on 175mm cranks with no probs, I've gone super short. 172.5
I may be asking fitment questions, but have had a look here and on WW.

[FigTree]

Is there a guide on whether you need spacers / how many with this crank? I'm using a tarmac with BSA. Or can we work it out by measuring the spindle length or distance between crank arms and the BB width?

[Da11as]

Is there a guide on whether you need spacers / how many with this crank? I'm using a tarmac with BSA. Or can we work it out by measuring the spindle length or distance between crank arms and the BB width?

It all depends on your frame and bottom bracket.Check your crank distance from some symmetric part of your bike (e.g. bottle cage bolts) and, if necessary, adjust to achieve equal distance on both sides.

[FigTree]

So I have mostly installed the cranks tonight, they were a bit of a faff to get the spacing right (mainly because I didn't have a good reference point to measure to that I was certain was on the centreline). I ended up with 1mm spacer on the DS and using the preload collar to take up the space on the NDS. I haven't adjusted the FD yet but the crank arm just brushes it as you cycle it.

One thing I did find was the spindle was way tighter to push through the Bb (Shimano BBR60) than the DA it replaced, I had to use a mallet (I could always push the DA crank in by hand) - has anyone else found this?

[warthog]

They say the only stupid question is the one you don't ask.
Anyway, my best wasn't very good and it was a long time ago. I would like to put 50/34 chainrings on my Bigrock crankset not the 52/36 on my current Ultegra 8100 cranks.
Just would like to confirm this will fit despite the rings appearing profiled to fit Shimano cranks?

https://a.aliexpress.com/_mLW462v

[jonathanf2]

They say the only stupid question is the one you don't ask.
Anyway, my best wasn't very good and it was a long time ago. I would like to put 50/34 chainrings on my Bigrock crankset not the 52/36 on my current Ultegra 8100 cranks.
Just would like to confirm this will fit despite the rings appearing profiled to fit Shimano cranks?

https://a.aliexpress.com/_mLW462v

As long as you have the appropriate 110 bcd 4 bolt adapter, the Stone chainrings are very good. They shift as well as my Dura Ace and Ultegra chainrings I was using.

[warthog]

As long as you have the appropriate 110 bcd 4 bolt adapter, the Stone chainrings are very good. They shift as well as my Dura Ace and Ultegra chainrings I was using.

https://imgur.com/a/MSjM6DL#IzEkBlT

Just the adaptor the Bigrock cranks came with. Doesn't have the profiling the Shimano cranks have

[warthog]

There are photos on WW of shimano rings fitted to that spider, so a bit of dumb question sorry.


DJC bikes sent me a whatsapp and asked for a photo of the chainset. Confirmed it would fit before sending. So that was good of them. 👌

[Yunglord]

The cranks comes with the above spider which indeed fits Shimano Chainrings.

[FigTree]

With the cranks installed and a 1mm spacer on the DS to get the crank arms spaced evenly, I have a 2mm ish gap between the preload collar and NDS crank arm- is this too much? It seems to week fine but it's a bit when looking down and seeing the gap. I'm considering installing a 1mm spacer between the preload collar and BB.

[Da11as]

With the cranks installed and a 1mm spacer on the DS to get the crank arms spaced evenly, I have a 2mm ish gap between the preload collar and NDS crank arm- is this too much? It seems to week fine but it's a bit when looking down and seeing the gap. I'm considering installing a 1mm spacer between the preload collar and BB.

So there is nothing in the gap? You have to fill it with spacers, else there will be high risk of knee injury after it slips to the opposite side. But I bet you get into shifting problems first.

[Wet Noodle]

With the cranks installed and a 1mm spacer on the DS to get the crank arms spaced evenly, I have a 2mm ish gap between the preload collar and NDS crank arm- is this too much? It seems to week fine but it's a bit when looking down and seeing the gap. I'm considering installing a 1mm spacer between the preload collar and BB.

So there is nothing in the gap? You have to fill it with spacers, else there will be high risk of knee injury after it slips to the opposite side. But I bet you get into shifting problems first.

What?!

Did they change the design to one of those floating preload adjusters (where the male thread part is just shoved onto the axle and not part of the crank arm)?

Or are you saying that the preload collar doesn't have enough thread engagement anymore at this position? I don't know how long the thread is / how far you can screw the collar off before it gets risky. If the male thread is still part of the crank arm, you would definitely not fill up the gap between crank arm and preload collar with spacers. If the adjustment range isn't enough, you'd put the spacer(s) between the collar (the nut, so to speak) and the bb side.

[FigTree]

So there is nothing in the gap? You have to fill it with spacers, else there will be high risk of knee injury after it slips to the opposite side. But I bet you get into shifting problems first.


What?!

Did they change the design to one of those floating preload adjusters (where the male thread part is just shoved onto the axle and not part of the crank arm)?

Or are you saying that the preload collar doesn't have enough thread engagement anymore at this position? I don't know how long the thread is / how far you can screw the collar off before it gets risky. If the male thread is still part of the crank arm, you would definitely not fill up the gap between crank arm and preload collar with spacers. If the adjustment range isn't enough, you'd put the spacer(s) between the collar (the nut, so to speak) and the bb side.

The "gap" is between the NDS crank arm and collar and is filled by the thread the collar threads on. There are only 2 issues I see - 1. It looks strange and 2. I'm not sure how much of the thread is engaged on the collar with it adjusted as is, so could lead to issues.

If someone has a crank that's not installed and could measure the length of the thread, it would be appreciated.

[Wet Noodle]

The "gap" is between the NDS crank arm and collar and is filled by the thread the collar threads on. There are only 2 issues I see - 1. It looks strange and 2. I'm not sure how much of the thread is engaged on the collar with it adjusted as is, so could lead to issues.

OK, that makes sense. If you want to be on the safe side, just turn the collar back some and put spacers between it and the bb (assuming there are still spacers left (and that they're of the right size, as to not rub on the bb cup or anything)).

[warthog]

The "gap" is between the NDS crank arm and collar and is filled by the thread the collar threads on. There are only 2 issues I see - 1. It looks strange and 2. I'm not sure how much of the thread is engaged on the collar with it adjusted as is, so could lead to issues.

If someone has a crank that's not installed and could measure the length of the thread, it would be appreciated.

I measured the spacer with my verniers. The threaded extension on the nds crank arm was ~5mm. Couldn't get a photo with only 2 hands sorry.