Mudguard sizes I’m confused

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brychan
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Re: Mudguard sizes I’m confused

Postby brychan » 24 Dec 2017, 7:52pm

Thanks Brucey you beat me to it I’ve found a photo where the staves were attached to P clips which looks a good idea. All I have to do is measure my forks circumference and get the right clips
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elPedro666
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Re: Mudguard sizes I’m confused

Postby elPedro666 » 26 Dec 2017, 10:23am

Brychan, a couple of photos of your dropouts, seat and chainstay bridges, and tyre clearance under the fork crown would be really useful. All the Boardmans (Boardmen?! ) I've seen have been really thoughtfully equipped with mounting points.

Discs can definitely be a pain though, two solutions that are working here are to space the stays out with 30mm (I think) hex nipple thingies, or to carefully shape the stays around the calipers (a faff, but very satisfying!). Forgive the busy (and apparently sideways) photos, hopefully you can make out what I'm on about...

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pwa
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Re: Mudguard sizes I’m confused

Postby pwa » 26 Dec 2017, 12:40pm

elPedro666 wrote:Brychan, a couple of photos of your dropouts, seat and chainstay bridges, and tyre clearance under the fork crown would be really useful. All the Boardmans (Boardmen?! ) I've seen have been really thoughtfully equipped with mounting points.

Discs can definitely be a pain though, two solutions that are working here are to space the stays out with 30mm (I think) hex nipple thingies, or to carefully shape the stays around the calipers (a faff, but very satisfying!). Forgive the busy (and apparently sideways) photos, hopefully you can make out what I'm on about...

ImageImage

I'm a trendy consumer. Just look at my wobbly using hovercraft full of eels.


Nice controlled bending of the stays.

Brucey
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Re: Mudguard sizes I’m confused

Postby Brucey » 26 Dec 2017, 1:15pm

pwa wrote:
Nice controlled bending of the stays.


except it looks like the lower stay will foul the caliper if the caliper arm is allowed to return fully, as it is meant to be set; as it is, the brake arm looks almost half-way through its travel in the rest position.

cheers
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Brucey
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Re: Mudguard sizes I’m confused

Postby Brucey » 26 Dec 2017, 1:24pm

brychan wrote:Thanks Brucey you beat me to it I’ve found a photo where the staves were attached to P clips which looks a good idea. All I have to do is measure my forks circumference and get the right clips


as per an earlier post, with a current suntour fork there should be bosses on the fork legs that allow the stays to be fitted using angle brackets; if so no need for P clips.

Smaller P clips are required on bike like yours (with no seatstay bridge) for the rear mudguard mounting.

BTW the advice in an above post to chop the plastic banjos down and to superglue the caps over the stay ends is not how SKS intend you to do the job. If used as intended (which is a bit fiddly admittedly) the banjos ensure that the caps cannot come off, but there is limited scope for further adjustment of the stay length.

cheers
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PH
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Re: Mudguard sizes I’m confused

Postby PH » 26 Dec 2017, 6:22pm

Brucey wrote:
BTW I would probably buy 35mm mudguards for your bike.

cheers

I'm sceptical that the stock tyres on a Boardman MX Sport will fit under a 35mm guard.

Debs
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Re: Mudguard sizes I’m confused

Postby Debs » 26 Dec 2017, 7:49pm

700x28mm tyres with fit under 35mm mudguards okay - albeit with some careful fitment.
Tyres wider than 28mm will most probably need wider mudguards.

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elPedro666
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Re: Mudguard sizes I’m confused

Postby elPedro666 » 26 Dec 2017, 8:10pm

Brucey wrote:
pwa wrote:
Nice controlled bending of the stays.


except it looks like the lower stay will foul the caliper if the caliper arm is allowed to return fully, as it is meant to be set; as it is, the brake arm looks almost half-way through its travel in the rest position.

cheers
Thanks very much pwa, I have to admit I was really pleased with myself afterwards, I am a bit sad!

I set BB5/7 so that the arm is perpendicular to the cable at the moment of full squeezing (technical term) to give max power at that point - it is very tight but nothing fouls anywhere.

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Re: Mudguard sizes I’m confused

Postby Brucey » 26 Dec 2017, 9:57pm

elPedro666 wrote:
I set BB5/7 so that the arm is perpendicular to the cable at the moment of full squeezing (technical term) to give max power at that point - it is very tight but nothing fouls anywhere.


with some brakes that is a useful tactic because it affects braking power. BB5/7 does not fall into that category because there is a radiused tab on the brake arm; over most of the working range the cable makes a nice tangent to this tab and the leverage that the brake exerts is not affected.

Is there a downside to setting the arm (not as per the manual) as you have? Sure; there are two issues;

1) if the arm does not return fully to the start of the ramps (inside the mechanism) then the moving pad can more easily become slightly twisted, with one or more of the balls out of place on the ramps. This can cause the mechanism to wear oddly and/or bind. You can see that this has been happening because the moving part of the mechanism will have worn the bore of the caliper body abnormally (much more than the pad backing, which should take the braking load reaction force into the caliper body). If set as per the manufacturer's instructions on BB7 the balls ought to 'reset' every time the brake is released.

2) with some versions of the BB5/7 range the arm has limited travel and the brake can just stop working because the brake is too far through its stroke. The worst culprit for this is BB5 road, IIRC. With this brake model the top of the arm will move about 5mm from where you have it set before it will hit a hard stop and the brake will just stop working. BB7 and MTB variants are not as bad as this but the same thing will apply if the lever moves too far.

So anyway I strongly suspect you would be better off with an equally artistic bend in the lower stay, and the arm set further back, nearer the start of its stroke, as the manufacturer recommends.

cheers
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curzons246
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Re: Mudguard sizes I’m confused

Postby curzons246 » 9 Jan 2021, 4:11pm

I wish I’d seen Robs guide before I learnt by the ‘trial and error method’ thanks Rob

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robgul
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Re: Mudguard sizes I’m confused

Postby robgul » 9 Jan 2021, 4:36pm

curzons246 wrote:I wish I’d seen Robs guide before I learnt by the ‘trial and error method’ thanks Rob


There was quite a bit of swearing and dopping the retaining bolts on the floor before I mastered the technique!

The other trick with mudguards, which is detailed somewhere on this or one of the other fora, where there isn't enough bridge clearance is to
a) cut the front mudguard just in front of the rivetted clip and fix that to the back of the fork crown (so no mudguard through the fork) and
b) for the rear cut the mudguard into two parts, the arc from the BB to the bridge fixed to the brake caliper - and then fabricate a top-hat shaped piece of metal to make a bridge over the stay bridge and rivet it to the rear section of the mudguard. * It's a very crude solution but it can be done quite neatly and it works!

* this is illustrated with a simple diagram in one the Bicycle Briefings sheets on my website - they are being revised at the moment but the direct link to the pdf is
http://www.cycle-endtoend.org.uk/RobDoc ... -oct13.pdf
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Brucey
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Re: Mudguard sizes I’m confused

Postby Brucey » 9 Jan 2021, 6:26pm

brackets that 'jump' the brake caliper were available from the 1980s as part of 'D. Salmon' aluminium mudguards.

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but are not difficult to make. Obviously the brake caliper sees almost the same amount of muck as if the mudguard wasn't there at all.

cheers
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robgul
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Re: Mudguard sizes I’m confused

Postby robgul » 9 Jan 2021, 6:59pm

Brucey wrote:brackets that 'jump' the brake caliper were available from the 1980s as part of 'D. Salmon' aluminium mudguards.

Image

but are not difficult to make. Obviously the brake caliper sees almost the same amount of muck as if the mudguard wasn't there at all.

cheers


Ah - you've rumbled me - I had one years ago on ancient French bike someone gave me for parts (and a large collection of rust :lol: ) - could have been a Gitane? The brake does need a post-ride clean but at least you don't get muck up the back of your jacket.
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Debs
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Re: Mudguard sizes I’m confused

Postby Debs » 10 Jan 2021, 12:47am

Brucey wrote:Obviously the brake calliper sees almost the same amount of muck as if the mudguard wasn't there at all.

cheers


When i had a split rear mudguard on my old winter hack, i zip-tided a bit of old inner tube to gaiter the exposed calliper.
Very easy to do and does the job.

rmurphy195
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Re: Mudguard sizes I’m confused

Postby rmurphy195 » 12 Jan 2021, 11:18am

Attached are piccies of the front stays on my disc-equipped tourer. You have to be careful of how much you bend them otherwise they won't reach the mudguard!

For the rear, make sure the front of the mudguard protrudes below the BB by bout an inch or so to protect the chainstays from grit!
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