Racework road crankset issues

[aliexpress_junkie]

Hi guys,

I got this crankset

https://www.aliexpress.com/item/1005003136515216.html

And my road bike has a BSA BB with a Shimano Tiagra threaded BB. The old crankset was a Shimano Tiagra crankset. BB has no spacers and the old crankset worked fine.

With the new Racework crankset I put it in the Shimano BB, but when I use the pre-load screw on the NDS arm no matter how tight I turn there's still lots of play in the crank (from left to right). Heck I even end up bottoming the screw and it does nothing on the preload. Only way I managed to remove the slack is pressing the crank arm and the crankset together, and then tightening the NDS crankarm pinch bolts. So all in all the preload screw isn't doing anything for me since there's too much slack in the system.

Am I missing anything here? I'm thinking maybe the crank is made for a MTB bb (73mm vs 68mm) and it's the only way that would work with the preload screw. I thought road bikes didn't need the spacers for a BSA BB when using a road crankset, that's why I never put the spacers...

Thanks!

[mrdawson]

maybe dumb question, but double checking...  You're trying to set the preload before tightening the crank-arm yes?  pics / vids of the play you're experiencing?

[mrdawson]

also, have you measured the width of bb?  tried using the BB provided instead of the shimano one?

[aliexpress_junkie]

Hi guys, two very good questions!

Yes I always set the preload with the pinch bolts loose, I can even see the crank arm gets moved a bit and some of the play is removed, but it quickly bottoms out and there's still 1 or 2mm left of loose that I can move from left to right by hand.

I didn't measure the width of the BB, but good point, I might have to use the one provided with the crankset, I expected it to be the same as a Shimano one since the diameter was hollowtech compatible (24mm). I'll do that and come back right away.

You should see the hackish way I "preloaded" the whole thing with a wood clamp just enough so that's no play and it spins freely and tightening the pinch bolts. When I did that I could clearly see the axle protruding from the NDS crankarm and the preload thing pushing against nothing.

I'll try and take some pictures tonight.

[aliexpress_junkie]

Hi guys, sorry for the late reply,

I ended up measuring the cups again, and I noticed the ones that came with the BB are around 0.75mm thicker on each side, which is definitely something I missed!

I removed the Shimano cups and used the ones that came with the BB, and now the preload works perfectly fine without using any spacers. So I was right in thinking that the spacers are really for installing the BB on a mtb wide frame, but I was wrong in thinking the cups were always the same width. I usually disregarded those BBs that came with aliexpress cranksets as from my experience the bearings die very quickly, but maybe it's possible to just replace them with better bearings in the future...

Anyway thanks for the help guys!

[mrdawson]

Nice.  Glad things worked.  But dumb that the BB isn't shimano spec.

[jefflinde]

I have had similar issues and Wheels Mfg sells spacers that fit the 24mm spindle.  The ones I have are .5mm thick so one or two per side and you are all set.  Then you can use the Shimano BB. 

[Zomb1e]

I have had similar issues and Wheels Mfg sells spacers that fit the 24mm spindle.  The ones I have are .5mm thick so one or two per side and you are all set.  Then you can use the Shimano BB.

There are also spacer sets on Ali - for both 24 and 29mm spindles. In the set there are 3x0.2mm steel spacers and 3 aluminum ones: 1, 2 and 3mm. Whole set costs nearly nothing.