Help!....Replacement crank bolt for Bosch line+...Raleigh Motus GT

tuniwes

Finding my (electric) wheels
Aug 16, 2020
13
12
Left hand crank fell off a week ago, fortunately only a mile from home. The state of the crank arm spline was not good so ordered a new Miranda replacement that arrived promptly.

I'm really struggling to find a reliable source for the 8mm hex 10mm thread crank bolt!......very frustrating

The bike is only 6 months old, the supplier said not covered by warranty, periodic tightening of essential bolts is the owners responsibility.....I agree, it has done 1,100 miles so lesson learned.

Any ideas where to get this friggin bolt please

Thanks
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
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Left hand crank fell off a week ago, fortunately only a mile from home. The state of the crank arm spline was not good so ordered a new Miranda replacement that arrived promptly.

I'm really struggling to find a reliable source for the 8mm hex 10mm thread crank bolt!......very frustrating

The bike is only 6 months old, the supplier said not covered by warranty, periodic tightening of essential bolts is the owners responsibility.....I agree, it has done 1,100 miles so lesson learned.

Any ideas where to get this friggin bolt please

Thanks
May I suggest two things:-
1) when you have a question about a part, if possible make a close up and clear photo, with a ruler for sizing, and post it here as well, with your question.
2) Check out ebay and other online suppliers, as it is probably a pretty standard part.
Guessing only though, as I have never ever seen the part myself.
regards and best wishes for a great day
Andy
 

Gliggsy

Pedelecer
May 15, 2020
50
10
Got to say I've been around nuts and bolts all my life and I'm struggling to picture 10mm thread with 8mm head!!!?
 
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Nealh

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Aug 7, 2014
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West Sx RH
Bosch thread with resident Bosch expert SW's input.

 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
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soundwave

Esteemed Pedelecer
May 23, 2015
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tuniwes

Finding my (electric) wheels
Aug 16, 2020
13
12
Thanks everybody for your suggestions and help.....finally sourced it at Holland bikes, same company that supplied the replacement crank, for anybody with the same problem:


With delivery 20 quid for a friggin bolt!....outrageous!...still, will get me back on the road again, that's the main thing and a huge lesson learned....check bolt tightness every 500 miles, when it failed 1,150 since April...... the "E bike experience" through the first lockdown changed my life and stopped me going mad after a days stuck in front of the PC working from home
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
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Thanks everybody for your suggestions and help.....finally sourced it at Holland bikes, same company that supplied the replacement crank, for anybody with the same problem:


With delivery 20 quid for a friggin bolt!....outrageous!...still, will get me back on the road again, that's the main thing and a huge lesson learned....check bolt tightness every 500 miles, when it failed 1,150 since April...... the "E bike experience" through the first lockdown changed my life and stopped me going mad after a days stuck in front of the PC working from home
There are several cheaper options in the UK that list a far lower postage, for instance here:-
Regards
Andy
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
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That is an 8mm bolt, halfords stock those......my bolt is the same head size but 10mm thread
That is an important difference! But super expensive postage.

I have no need of them myself, but I was looking at one of the ebay ads, and actually it should be quite easy, to "make them up" yourself, using a High Qulaity Stainless 10mm Hex or TORX bolt of the correct length, suitable quality stainless washers of the same width and thickness, and a quality sealant to make sure that no water or dirt gets into the thread area.....
That would appear to be the Job done for very little money.
That plastic "crown" on the original (expensive) bolts, is apparently just to prevent dirt and moisture getting in according to a biking friend of mine, with little or no guarantee that it won't!
And that plastic is costing more than the same weight of Gold I would imagine! Though I have none to hand to weigh!
Perhaps someone here has already made up such a method, before I thought of it!
As IMHO, it would seem pretty obvious if you first had the bits in your hand and took a good look at them.....
Just a thought!
Regards
Andy
 

RoadieRoger

Esteemed Pedelecer
Nov 8, 2010
634
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It might be an idea to use thread locking compound . It works on square holes on crank to shaft as well as threads . It fixed a continuously falling off Halfords Cycle`s crank/pedal .
 

Ocsid

Pedelecer
Aug 2, 2017
212
140
77
Hampshire
That is an important difference! But super expensive postage.

I have no need of them myself, but I was looking at one of the ebay ads, and actually it should be quite easy, to "make them up" yourself, using a High Qulaity Stainless 10mm Hex or TORX bolt of the correct length, suitable quality stainless washers of the same width and thickness, and a quality sealant to make sure that no water or dirt gets into the thread area.....
That would appear to be the Job done for very little money.


Regards
Andy
Except that the "proper" bolt in this case is an M10 "Superfine" 10mm x 1 mm pitch, not the normal M10 "fine", which is 10mm x 1.25 pitch.

Great if you can find a source of the correct size bolts in one or two off, rather than a minium order, typically with such specials.
 

tuniwes

Finding my (electric) wheels
Aug 16, 2020
13
12
Except that the "proper" bolt in this case is an M10 "Superfine" 10mm x 1 mm pitch, not the normal M10 "fine", which is 10mm x 1.25 pitch.

Great if you can find a source of the correct size bolts in one or two off, rather than a minium order, typically with such specials.

Well the 10MM bolts arrived from Holland yesterday........The packaging left me speechless!
Box size 300mm x 200mm x 150mm....tiny plastic packet containing two 10mm bolts sitting in the middle of two inflatable plastic air pillows .

One things for sure I will be regularly checking that they are tight going forward.

Thanks for your help and suggestions