Rear light mounting problems

General cycling advice ( NOT technical ! )
Brucey
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Re: Rear light mounting problems

Postby Brucey » 16 Nov 2020, 10:41am

FWIW I have found that even if the lamp is fairly lightweight, the extra weight of it (if positioned at the rear of the mudguard) often hastens the demise of a mudguard.

Most rear light positions are vulnerable to them being knocked. This will either move the lamp, or break it. 'Breaking' is very common with the usual confection of flimsy plastic parts which seems to pass for a rear light these days. 'Moving' is relatively harmless if the lamp is on the upper part of the seatstay, but potentially disastrous if it can 'move' into the wheel.

I have long intended to mount the few components required for a basic rear dynamo light inside a simple rear reflector unit. However given that the reflector has been knocked off the last three sets of mudguards I have used (in some cases breaking the mudguard in the process), thus far, I simply have not bothered.

FWIW I use a simple dynamo lamp mounted high up on the seatstay; it gets knocked quite often, and simply swivels around the seatstay because it is mounted using a (metal) P clip. I would have broken at least a dozen lights had the mounting been more rigid.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

roubaixtuesday
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Re: Rear light mounting problems

Postby roubaixtuesday » 16 Nov 2020, 10:46am

Many (most?) Lights have ways to fit angle adjusted to seat stays.

Cateye do a seat stay mount, I have one on a MTB, works well.

Planet x dogstar likewise. I have one and works well

https://www.planetx.co.uk/i/q/LIJODOG10 ... -100-lumen

IIRC exposure rear lights likewise.

tatanab
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Re: Rear light mounting problems

Postby tatanab » 16 Nov 2020, 10:48am

Paul Smith SRCC wrote:You can always fettle many to the mudguard eye as well
Light to mudguard eye.jpg
Be aware that there is a legal minimum height for a rear light at 350mm. Not that anybody is likely to worry about that and the example shown is going to be above that.

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Paul Smith SRCC
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Re: Rear light mounting problems

Postby Paul Smith SRCC » 16 Nov 2020, 10:54am

tatanab wrote:
Paul Smith SRCC wrote:You can always fettle many to the mudguard eye as well
Light to mudguard eye.jpg
Be aware that there is a legal minimum height for a rear light at 350mm. Not that anybody is likely to worry about that and the example shown is going to be above that.

Agreed and yes it is slightly higher than 350mm but in fairness I mount one there just because I can, I wouldn't like that as my only rear light or even that one on the mudguard either for that matter.

In the winter I have that Smart 1/2 watt Super flash one on the mudguard eye, the Cateye TL AU100 on the guard, an older Moon Commet another on the back of the rack, a latter edition Moon Commet under the saddle rail and a Bontrager helmet light! I like that they quite far apart from each other and that the mudguard eye located light is on the right side of the bike and gives me a feeling of width, plus I can glance down and reassuringly see it's actually 'on' where as the others are not in my field of vision.
cateye TL AU100 on mudguard.jpg

pwa
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Re: Rear light mounting problems

Postby pwa » 16 Nov 2020, 1:14pm

cricklewood_graeme wrote:20201115_152015.jpg
For my regular weekly/weekend rides I have a wedge bag attached to my seat-post and no carrier. I wonder if anyone knows of a way of attaching a rear battery light to the mudguard or the seat-stays. Most lights I am aware of seem to be designed to be attachable only to the seat-post. I don't recommend the Newboler wedge bag BTW. It's difficult to mount and difficult to access. But that's for another post to this forum. :evil:

With a similar set-up to yours I have managed in the past to fit a pair of lights, one to each of the unused lower rack bosses. It involves a bit of bodging in the back of the shed, but it can work really well.

backnotes
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Re: Rear light mounting problems

Postby backnotes » 16 Nov 2020, 1:38pm

NATURAL ANKLING wrote: although it seems logical to mount it on the mudguard where the reflector normally it still gets knocked there too.


There's a metal "bash guard" available from B+M for the Secula that may fit other lights that mount where the reflector normally goes. My Secula is the dynamo version, but I believe it also fits the battery version. The design is such that you can still see the light from side-on, though it will obviously cut off some light between there and the view from behind.

IMG_0622.jpg
IMG_0618.jpg

mcshroom
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Re: Rear light mounting problems

Postby mcshroom » 16 Nov 2020, 5:31pm

One I've been impressed with on a Friday Night Ride to the Coast ride before was a fibre-flare attached to the seatstay.

It was very visible.

I've used Spanninga Pixel lights there before, but I think the extra vibration of the chromoplastics guard shook them too much. Both failed eventually.

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andrew_s
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Re: Rear light mounting problems

Postby andrew_s » 16 Nov 2020, 9:08pm

Paul Smith SRCC wrote:In the winter I have that Smart 1/2 watt Super flash one on the mudguard eye, the Cateye TL AU100 on the guard
cateye TL AU100 on mudguard.jpg

That AU100 is incorrectly mounted, being aimed upwards at around 30 degrees. This will reduce the brightness as seen by a following car to a small fraction of what it should be. Even the reflector won't work properly (they only work up to an angle of about 15 degrees).

Mounting the light so that the seam between the black and red sections is vertical is a common error.
It's the reflector face that should be vertical, which is parallel to the rear of the light if you use the screw rather than the tiltable QR clip. This makes it a pretty much useless light to fit to a mudguard (quite apart from the weight of two AA batteries).

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Paul Smith SRCC
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Re: Rear light mounting problems

Postby Paul Smith SRCC » 16 Nov 2020, 11:15pm

andrew_s wrote:
Paul Smith SRCC wrote:In the winter I have that Smart 1/2 watt Super flash one on the mudguard eye, the Cateye TL AU100 on the guard
cateye TL AU100 on mudguard.jpg

That AU100 is incorrectly mounted, being aimed upwards at around 30 degrees. This will reduce the brightness as seen by a following car to a small fraction of what it should be. Even the reflector won't work properly (they only work up to an angle of about 15 degrees).

Mounting the light so that the seam between the black and red sections is vertical is a common error.
It's the reflector face that should be vertical, which is parallel to the rear of the light if you use the screw rather than the tiltable QR clip. This makes it a pretty much useless light to fit to a mudguard (quite apart from the weight of two AA batteries).

That's what you referenced in 2008 as well andrew_s.

When I fitted them way back then on three of my bikes I spent some time at various distances trying to work out what was the most effective and reflector aside whatever way up it was didn't seem to make a difference, even though they point in the wrong direction you can see a bright red glow from directly behind. It was one of three lights in 2008 and now one of five if you include my helmet light so I quite like that they are not all focusing in an almost identical direction.

For sure in 2020 LEDS are now brighter as well as much lighter, but that's not the same as saying "This makes it a pretty much useless light to fit to a mudguard".
cateye TL AU100.jpg
Last edited by Paul Smith SRCC on 16 Nov 2020, 11:18pm, edited 1 time in total.

AndyK
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Re: Rear light mounting problems

Postby AndyK » 16 Nov 2020, 11:18pm

Many of the Moon rear lights (Comet-X, Sirius, Cerberus, Nebula...) attach using rubber "O-rings" (they're not really O-rings but close enough) and come with two or more different sizes of O-ring.

My Moon Comet-X attaches neatly to the narrow seat stay on my 531C-framed winter road bike using the smaller O-ring. I usually put it just above the bridge so the mudguard gives it some protection but it's still well below the seatpack. It will rotate a little if knocked, but not much, and road vibration alone isn't enough to displace it. The bracket is angle-adjustable so you can make sure the light is shining horizontally. Excellent light too.

IMG_20201116_225916 (1).jpg

(No, I haven't cleaned the bike since Sunday's ride.)

If the OP studies Brucey's photo carefully and attaches his wedge bag correctly, a light like this should work for him.

markjohnobrien
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Re: Rear light mounting problems

Postby markjohnobrien » 17 Nov 2020, 10:34am

backnotes wrote:
NATURAL ANKLING wrote: although it seems logical to mount it on the mudguard where the reflector normally it still gets knocked there too.


There's a metal "bash guard" available from B+M for the Secula that may fit other lights that mount where the reflector normally goes. My Secula is the dynamo version, but I believe it also fits the battery version. The design is such that you can still see the light from side-on, though it will obviously cut off some light between there and the view from behind.

IMG_0622.jpgIMG_0618.jpg


I’ve got a mudguard mounted dynamo Secula: works well and no problems with mudguard breaking.

Jdsk
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Re: Rear light mounting problems

Postby Jdsk » 17 Nov 2020, 10:38am

tatanab wrote:
Paul Smith SRCC wrote:You can always fettle many to the mudguard eye as well
Light to mudguard eye.jpg
Be aware that there is a legal minimum height for a rear light at 350mm. Not that anybody is likely to worry about that and the example shown is going to be above that.

IIUC you only have to have one that is compliant, you can add others that aren't.

Jonathan

thirdcrank
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Re: Rear light mounting problems

Postby thirdcrank » 17 Nov 2020, 11:01am

I'm too idle to dig my copy out and I this may not be in the current edition but in Cyclecraft John Franklin has made the point that a rider needs to be perceived as a cyclist ie a single rear lamp, and not eg two lamps with one on either side which might be taken to be a motor vehicle much further away.

With apologies to a well-known military phrase or saying, these days, if it's stationary it's a Christmas tree, and if it moves it's a cyclist

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simonineaston
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Re: Rear light mounting problems

Postby simonineaston » 17 Nov 2020, 11:15am

When I had a similar setup, I simply attached a battery-powered rear lamp to the back of the wedge bag.
byyeee,
SiE

tatanab
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Re: Rear light mounting problems

Postby tatanab » 17 Nov 2020, 11:40am

thirdcrank wrote:I'm too idle to dig my copy out and I this may not be in the current edition but in Cyclecraft John Franklin has made the point that a rider needs to be perceived as a cyclist ie a single rear lamp, and not eg two lamps with one on either side which might be taken to be a motor vehicle much further away.
In the book I think he was referring mainly to front lights, although I can see it for rear as well. As you say, he makes the point that perspicuity is as important as conspicuity. I don't have a copy of the book, but I recall reading the first edition about 25 years ago and certain things stuck in my mind.

An example from the 1960s. My father was driving the family and pulled out to pass a lorry. He had seen two small lights that seemed to be far in the distance. Fortunately before it was too late he realised it was a Jaguar running on side lights.