ive fitted the bosch cx repair kit - Cannot torque cranks correctly now?

[Razorx]

Ive managed to install the servicekit on my bosch and everything works great except for one thing.
The cranks are supposed to be torqued to something like 45-65 nM. Dont remember exactly. But if i try to torque them to anything more than handtight it gets to tight and i can almost not pedal the cranks.

Does anyone have any idea why this is?

 

[Mikerb]

direct mount or spider? Have you tried one crank at a time to see which one is causing the issue. The only reason I can see for the cranks not rotating freely is that the crank is rubbing against the motor casing so either wrongly installed or the wrong cranks.

 

[Razorx]

No i have not tryed one ar a time. Gonna try that!
I bought cranks tht said 'for bosch cx gen 2' . I thought all of the would work... Stupid of me.

They are direct mount.

 

[Mikerb]

No i have not tryed one ar a time. Gonna try that!
I bought cranks tht said 'for bosch cx gen 2' . I thought all of the would work... Stupid of me.

They are direct mount.

....I think you mean the chainwheel is direct mount? What bike is it...what motor?

 

[Razorx]

Its a Scott egenius 730 plus. Bosch cx gen 2.

 

[Mikerb]

I thought that bike was fitted with a spider and the small 16t chainring. Spider/chainring and cranks should be for boost fitting to match the 148mm rear hub. Maybe you bought the wrong kit?

 

[Razorx]

Oh.. Did not think of the boost and that would have impact on cranks.

In the picture the old crank is on the right. And I see the diffrence. So that may be it!

I can not find anything on Miranda bike parts homepage that have boost in the name of the cranks.. Ist just Q:16, 55Q and all of that stuff that dont make any sense to me...

What do i need to look for!? Ive attached a picture with both my cranks... What out of all those letters and numbers is what i need to know to buy new cranks!?

The left crank says "27 16", the righ crank says "47 R 16"... i dont get it.

 

[Mikerb]

Oh.. Did not think of the boost and that would have impact on cranks.

In the picture the old crank is on the right. And I see the diffrence. So that may be it!

I can not find anything on Miranda bike parts homepage that have boost in the name of the cranks.. Ist just Q:16, 55Q and all of that stuff that dont make any sense to me...

What do i need to look for!? Ive attached a picture with both my cranks... What out of all those letters and numbers is what i need to know to buy new cranks!?

The left crank says "27 16", the righ crank says "47 R 16"... i dont get it.

View attachment 95953

View attachment 95963

I'm not sure you understood what I was asking about the chainring. I thought the system on your bike consisted a spider to which is bolted a 16 t chain ring. The cranks are separate. The spider and or chainring will be boost....often referred to as+3. It means the chainring sits 3mm further out to create the correct chainline for a boost/148mm rear hub. The 148mm rear hub is 6mm wider than the standard 142mm hub (non boost) with that 6mm shared equally both sides of the hub. The cassette is therefore 3mm further out.

The cranks just need to an ISIS fitting (note...not BNI which is mini ISIS), the length you want (typically 165mm to 175mm) . They can be self extracting or not. The only other variable is Q factor. Q factor is the distance between the 2 cranks at the points the pedals bolt on. A straight crank will produce a narrower q factor and a flared crank a wider q factor. It is really only important on an emtb/mtb to select a crank that has good clearance to the chainstays.
Have you changed the spider or chainwheel?

 

[Razorx]

Oh man... This is to advanced for me

The chainring is an 8.65mm offset thing... Its the same as original. No its not bolted to a spider.
It is a two parts.. A offset thing which is 8.65 mm and then the chainring.. Its not bolted to a spider. ill add a picture.

I have not changed the chainwheel. The only thing that is new is the crankarms.. Im guessing its the q factor that is the problem. They have to small or large q factor so when im installing it it rubs against the motor.

I dont get why they have it so hard to know what crankarms i have on originally... one could think when it says 16 on both crankarms maybe that would be Q:16? But the first cranks i bought were to tight even though they were Q:16... Why does such a simple thing has to be so hard

 

[Mikerb]

Oh man... This is to advanced for me

The chainring is an 8.65mm offset thing... Its the same as original. No its not bolted to a spider.
It is a two parts.. A offset thing which is 8.65 mm and then the chainring.. Its not bolted to a spider. ill add a picture.

I have not changed the chainwheel. The only thing that is new is the crankarms.. Im guessing its the q factor that is the problem. They have to small or large q factor so when im installing it it rubs against the motor.

I dont get why they have it so hard to know what crankarms i have on originally... one could think when it says 16 on both crankarms maybe that would be Q:16? But the first cranks i bought were to tight even though they were Q:16... Why does such a simple thing has to be so hard

View attachment 96093

This is what you have I think

 

[Razorx]

This is what you have I think

View attachment 96097

Neither the old cranks or the new had a sprider on them. Its just crankarms nothing more if thats what the round thing is.

 

[Mikerb]

The ones for sale above are just the crank Arms despite the product photo

 

[Razorx]

But i ha e those ride+ which

The ones for sale above are just the crank Arms despite the product photo

Yeah but i have those ride+ cranks already and They wont fit as they should. Those are the ones who i can not fit correctly. They get to tight :/

 

[Mikerb]

I think the problem definitely relates to that part of the crank but I think the original crank also has a deeper/longer spindle length.
Maybe the only way to resolve the issue is to seek advice from Scott bikes or a Scott bike dealer.

 

[Razorx]

The matt colored crank is my old crank arm its thicker.
Old one is wider...

But the new crank itself has a wider q factor...

 

[Mikerb]

Yes...which means you need cranks with the same spindle depth as your old ones. When you fit the crank on the Isiss motor spindle it sits against a shoulder once fully tightened. Your new ones being narrower are hitting the chainwheel/chain guard before the crank hits up against that spindle shoulder.
Use the measurement of your old cranks to check with the retailer for new ones....or buy Hope cranks...they have diagrams with all the measurements of their cranks.

Don't get confused between this measurement and q factor. The q factor is the distance between the cranks when fitted at the points the pedals bolt on. A flared shaped crank will deliver a wider q factor and the only reason that may be important is to ensure the crank does not foul the chainstay when rotated. Emtbs tend to provide room for wide tyres and therefore the width across the chainstays is wider.

 

[Razorx]

I went to my LBS and he had "scott delta boost cranks" and they work perfect.
Thank you everyone for your patience with my problem