Author Topic: thorn chainguards  (Read 3855 times)

PH

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Re: thorn chainguards
« Reply #30 on: November 05, 2017, 07:24:40 PM »
EDIT - Part duplicated what martinf was typing at the same time, but different enough not to bother changing...

Ok but i don't want to change my chainring now, so i don't know if i can use a chainguard up to 38 t with my actual chainring 40 t .. ?    :-\

Most probably not, the maximum T size will have the chain running just below the edge, the guard would at best be pointless if the chain was above the guard and if this wasn't the case with 40T it's hard to imagine why it wouldn't be advertised as such.
Chainring bolts - if you're currently running a single chainring in the outer position, you'll need to move it to in middle/inner position and put the guard where the chainring is now, this will need double bolts rather than the single you most likely have now. 
Also consider doing the above changes the chainline, if you wish to maintain the current one, you'll also need a different bottom bracket.
« Last Edit: November 05, 2017, 07:28:00 PM by PH »

Danneaux

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Re: thorn chainguards
« Reply #31 on: November 05, 2017, 07:32:49 PM »
Agreed with Martin; when I make my own bash guards, I do so by filing the teeth from old chainring that are 6 teeth larger than the 'ring I am trying to protect.

The experiences related by others in this thread matches my own.

All the best, Julien,

Dan.

mickeg

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Re: thorn chainguards
« Reply #32 on: November 05, 2017, 09:07:49 PM »
It is not clear to me if this is for a Rohloff bike or derailleur bike with a double/triple? 

And if it is for a Rohloff bike, does it have a double crank? 

And if it is a double with one chainring on a Rohloff bike, do the chainring bolts have the little spacers that come with the Rohloff that allow you to use the double length bolts with a single chainring on a double crank?

In other words, we can't make firm answers without knowing what the situation is.

For my Nomad (Rohloff) bike which has a double crank, I cut the teeth off a 52T chainring to use as a bashguard with a 44T chainring, thus 8 teeth difference.  That was a bit bigger than it needed to be but it was functional so that is what I use. 

Touring where I use a 36T chainring on the inner position on a double crank, I use a 44T chainring as a bashguard because if I conclude that the 36 is too low, I can add a few links to the chain and use the 44 instead.  But it looks a bit odd to have two chainrings and no front derailleur.

If you have a chainring in the outer position on a Rohloff bike and move that chainring to an inner position, that will change your chainline a bit.  My chainline is off about 5mm because I run my chain on a chainring on the inner postion, but my chainline would be perfect if I had the chainring in the outer position.  I see a 5mm out of line position as not a problem, but I have no clue what you have on your bike.

PH

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Re: thorn chainguards
« Reply #33 on: November 06, 2017, 01:08:41 AM »
It is not clear to me if this is for a Rohloff bike or derailleur bike with a double/triple? 

Well, the question is based on a single chainring...
Given that I doubt it matters whats on the back, IGH, SS, 1X

julio

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Re: thorn chainguards
« Reply #34 on: November 06, 2017, 03:22:40 PM »
You didn't say what you wanted the chainguard for:

1 keeping trousers or legs clean
2 stopping the chain jumping off the chainring (IMO very unlikely with a Rohloff)
3 as a bashguard to protect the chainring from rocks

I sent this link in my precedent message ..
https://www.sjscycles.co.uk/chainsets/thorn-high-quality-alloy-chainguard-for-110-pcd-rings-up-to-38t-black/

But thanks for yours explanations. I would like this chainguard firstly to protect trousers

I've only one bike, it's a Nomad with rohloff


As my chainring 40t, and my stainless chainring bolt are almost new, i prefer to ride like that without chainguard.. i'll see later.

 :) thanks
« Last Edit: November 06, 2017, 03:41:09 PM by julio »