Installing New Crankset

[Graham O]

I have a new GRX 46/30 chainset for the bike and with it comes a plastic part which screws into the non drive side of the axle once the crank is fitted. My question is whether this should be tightened before the crank bolts are tightened to provide preload, or is it mostly to stop muck getting in and should be tightened after the crank bolts? If the crank bolts are tightened first, presumably, the crank is just pushed by hand as far onto the axle as it will go.

Thanks for your help.

Graham

[fausto99]

I have a new GRX 46/30 chainset for the bike and with it comes a plastic part which screws into the non drive side of the axle once the crank is fitted. My question is whether this should be tightened before the crank bolts are tightened to provide preload, or is it mostly to stop muck getting in and should be tightened after the crank bolts? If the crank bolts are tightened first, presumably, the crank is just pushed ...

Yes, it provides preload, which according to most online sources should be very little. Finger tight, using a 25mm dia knurled wheel tool, is what I do. Then do up the pinch bolts evenly.

I don't think Shimano provide it with the chain set but you can buy a low cost small ebay one or a more expensive Park Tool one with integral handle or wings.

[cycleruk]

Fit the plastic screw first. Then you will need the tool that fits in the serrations of the screw to tighten and set the pre-load on the bearings. Then tighten the crank screws.
The pre-load is only finger tight as if the bearing pre-load is too high it will wear out the bearings quicker and cause drag.

Tool :- https://www.chainreactioncycles.com/shi ... p-prod3785

Park tool video :- https://www.bing.com/videos/search?q=Sh ... &FORM=VIRE

[Sweep]

Fit the plastic screw first. Then you will need the tool that fits in the serrations of the screw to tighten and set the pre-load on the bearings. Then tighten the crank screws.
The pre-load is only finger tight as if the bearing pre-load is too high it will wear out the bearings quicker and cause drag.

Tool :- https://www.chainreactioncycles.com/shi ... p-prod3785

Park tool video :- https://www.bing.com/videos/search?q=Sh ... &FORM=VIRE

Thanks for the vid cycleruk - have a bike with these cranks but never done any work on the cranks yet.
Question - do folk usually bother with a torque wrench as shown in the vid?

[Graham O]

Excellent information and that video was very informative. Now out to the garage to set it up properly.

With regards using a torque wrench, since I got a bike specific one, I use it all the time. When I used to work on cars a lot (bought lots of unreliable ones!) I got to know how much torque was a "good pull" on a 10" spanner quite accurately, but I'm too ham fisted to do the same on a bike.

Thanks for your help

Graham

[Jdsk]

Question - do folk usually bother with a torque wrench as shown in the vid?

I do.

Jonathan

[Eyebrox]

If you don't torque the crank bolts up tight enough they can work loose while pedalling and damage the teeth on the axle end. As happened to me before I bought a Park torque wrench ... and a new crankset.

[slowster]

The torque needed for the pre-load cap on the non-drive side crank arm is so low, that it's possible to tighten it enough without the dedicated tool. The big danger is over-tightening (which if anything is easier to do with the proper tool, as is deliberately demonstrated in the Park Tool crank installation video). When I've fitted and removed a Hollowtech 2 crank, I've used the edges of a plastic squeegee, i.e. any piece of flat material which will engage sufficiently with two gaps between splines 180 degrees apart will probably do, e.g. the corner of a credit card or a plastic ruler.

The specified range of torque for the two NDS crank arm bolts, i.e. 12Nm-14Nm, is so narrow that I would use a torque wrench. The particular design of the NDS Hollowtech II crank arm is one which is probably more likely to result in damage in the event of under- or over-tightening to any significant degree. Note also the Shimano instructions to check the tightness again after 100km. From page 4 of this manual - https://si.shimano.com/pdfs/dm/DM-FC0002-12-ENG.pdf:

The two left crank arm mounting bolts should be tightened in stages rather than fully tightened at once. Use a torque wrench to check that the final tightening torques are within the range of 12 - 14 N·m. Furthermore, after riding approximately 100km (60 miles), use a torque wrench to re-check the tightening torques. It is also important to periodically check the tightening torques.

[Sweep]

The torque needed for the pre-load cap on the non-drive side crank arm is so low, that it's possible to tighten it enough without the dedicated tool. The big danger is over-tightening (which if anything is easier to do with the proper tool, as is deliberately demonstrated in the Park Tool crank installation video). When I've fitted and removed a Hollowtech 2 crank, I've used the edges of a plastic squeegee, i.e. any piece of flat material which will engage sufficiently with two gaps between splines 180 degrees apart will probably do, e.g. the corner of a credit card or a plastic ruler.

The specified range of torque for the two NDS crank arm bolts, i.e. 12Nm-14Nm, is so narrow that I would use a torque wrench. The particular design of the NDS Hollowtech II crank arm is one which is probably more likely to result in damage in the event of under- or over-tightening to any significant degree. Note also the Shimano instructions to check the tightness again after 100km. From page 4 of this manual - https://si.shimano.com/pdfs/dm/DM-FC0002-12-ENG.pdf:

The two left crank arm mounting bolts should be tightened in stages rather than fully tightened at once. Use a torque wrench to check that the final tightening torques are within the range of 12 - 14 N·m. Furthermore, after riding approximately 100km (60 miles), use a torque wrench to re-check the tightening torques. It is also important to periodically check the tightening torques.

thanks for the caution slowster - perhaps I need to eventually get a torque wrench, though never used one in 25 years of serious cycling.

This one?

https://www.planetx.co.uk/i/q/TOJWMTWSV ... wrench-set


Oh for the simplicity of square taper - apply grease to threads/bolt, tighten damn tight, tight as you pretty much can, ride bike a bit, tighten again, maybe repeat last step again after a bit.

[Jdsk]

... perhaps I need to eventually get a torque wrench, though never used one in 25 years of serious cycling.

This one?

https://www.planetx.co.uk/i/q/TOJWMTWSV ... wrench-set

For bikes I own and like and recommend the Lifeline:
https://www.wiggle.co.uk/lifeline-essen ... ench-set-1
and that's the lowest price I've seen for some time.

Recent discussions:
viewtopic.php?f=5&t=146039
viewtopic.php?f=5&t=146964

Jonathan

[Sweep]

... perhaps I need to eventually get a torque wrench, though never used one in 25 years of serious cycling.

This one?

https://www.planetx.co.uk/i/q/TOJWMTWSV ... wrench-set

For bikes I own and like and recommend the Lifeline:
https://www.wiggle.co.uk/lifeline-essen ... ench-set-1
and that's the lowest price I've seen for some time.

Recent discussions:
viewtopic.php?f=5&t=146039
viewtopic.php?f=5&t=146964

Jonathan

thanks jdsk, will check out.
Probably a good idea for me - have always been somewhat hamfisted - partly why I've mainly stuck to steel bikes.

[slowster]

perhaps I need to eventually get a torque wrench, though never used one in 25 years of serious cycling.

This one?

https://www.planetx.co.uk/i/q/TOJWMTWSV ... wrench-set

I too would prefer the Wiggle Lifeline one, which a lot of people have and recommend (it comes up a lot if you search threads on this and other forums). £22.49 is the lowest price I've seen it at; normally it's £30 or more.

https://www.wiggle.co.uk/lifeline-essen ... ench-set-1

Oh for the simplicity of square taper - apply grease to threads/bolt, tighten damn tight, tight as you pretty much can, ride bike a bit, tighten again, maybe repeat last step again after a bit.

Agreed. Hollowtech II has advantages for racing bikes, but it's a lousy design for a touring bike. I see Surly fit a Hollowtech II chainset on the latest version of the Disc Trucker, which I guess is because they want to fit Shimano brand parts for the name recognition and Shimano presumably no longer have square taper chainsets in their range. Fitting a chainset for which it is important to "periodially check the tightening torques" to a bike which is designed for long distance touring, including in remote places, is simply a bad choice.

[irc]

While Shimano may recommend regular checks I have never done (wasn't aware of the need) a d haven't had any problems.

I have also fitted the cranks without a torque wrench just judging tight but not too tight by hand.

One advantage for touring is they are easy to remove with minimal tool. Useful, I found, when packing the bike for return from the USA and could only get hold of a very small cardboard box. The frame with bars, wheels, and seatpost off still needed the cranks removed to squeeze in.

All that said at £22 I may try the torque wrench.

[LittleGreyCat]

Now made a drive by purchase.
Thanks for the link to the torque wrench.

[cycleruk]

In reply to Sweep above - I have never used a torque wrench on a bike. But I have had a couple of things come loose over 60+ years of cycling. Obviously nowadays cycles have become more technical and it's no bad thing to stick to manufacturers recommendations.

My only thought about torque wrenches is how do you know that they are accurate and how can you test them?