Front disc brake with dropouts

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CJ
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Joined: 15 Jan 2007, 9:55pm

Re: Front disc brake with dropouts

Post by CJ »

Adnepos wrote:Can you confirm that you are quoting ISO as the standard for secondary retention?

No, I think that BS-EN 14764 would be taken as the most appropriate standard. There's an agreement however, between CEN and ISO that allows either to adopt each other's standards 'on the nod', so ISO may well be identical by now - or near identical. But it wasn't a few years ago. At that time work on ISO cycle standards - apart from cycle lighting - had ceased in deference to CEN.

Do you agree that the producer has a case to answer rather than the distributor?

You're probably right, I've not looked at GPSR in that much detail, but it's a general principle of UK consumer protection law that one proceeds against the retailer, as that's the only person one has a legal contract with. If the retailer is able to pass the buck to the manufacturer, that may be nice for the retailer (or one heck of a problem if the manufacturer is in China!), but should not be any of our business/problem.

And I think it's important to emphasise this. Bike shops are very fond of passing the buck, which is fair enough when one is seeking a remedy under the terms of a manufacturer's warranty, which may provide additional rights to those conferred by law, but retailers will also tend to steer you down the warranty path (typically keep you waiting months while the manufacturer looks for a way to wriggle out of it!) for matters that ARE covered by law and hence are first and foremost the retailer's responsibility.
Chris Juden
One lady owner, never raced or jumped.
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CJ
Posts: 3415
Joined: 15 Jan 2007, 9:55pm

Re: Front disc brake with dropouts

Post by CJ »

rmurphy195 wrote:The info pointed to by CJ is interesting - do the regulations apply, I wonder, when your LBS orders in the frame of your choice and builds it into a complete bike for use on the public road?

The reason I ask is that I did have this done a couple of years back, the bike was built but I didn't ask for reflectors or lamps, and specified a pair of pedals that did not have reflectors fitted. The tyres had reflective sidewalls, but his wasn't consciously asked for.

So the LBS supplied a bike without reflectors or lamps to front and rear, and without reflectors on the pedals. Does this mean that technically they were infringing the regs? If so, it's something that bike shops need to be aware of.

Unless you specified that the bike was wanted like that for the purpose of entering some kind of competitive event that required it to be thus, Yes.

Does the dealer need to worry? No. Because you are not a Trading Standards Officer and you (for whatever reason) really wanted it like that, so you are not going to complain. And since this National Government has squeezed Local Government to the point where Trading Standards departments have neither the staff nor the money to be pro-active on even quite serious threats to public safety. Test purchases are probably out of the question. I reckon the most that's likely to happen these days in any cycle shop is that a TSO may occasionally mooch around the bikes on display and perhaps ask a few odd questions about them.
Chris Juden
One lady owner, never raced or jumped.
Keezx
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Re: Front disc brake with dropouts

Post by Keezx »

reohn2 wrote:Properly desiged frames overcome the problem by having the dropouts facing forward so the wheel axle is forced into them rather than out of under braking :wink:


Pr0perly designed brakes and forks have the brake caliper on the front of the fork.
More then 20 years ago Jobst Brand discussed this in one his discussion threads on usenet:
http://yarchive.net/bike/disk_brakes.html
reohn2
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Re: Front disc brake with dropouts

Post by reohn2 »

Keezx wrote:
reohn2 wrote:Properly desiged frames overcome the problem by having the dropouts facing forward so the wheel axle is forced into them rather than out of under braking :wink:


Pr0perly designed brakes and forks have the brake caliper on the front of the fork.
More then 20 years ago Jobst Brand discussed this in one his discussion threads on usenet:
http://yarchive.net/bike/disk_brakes.html

Whilst I agree the caliper is better placed on the front of the fork leg,show me a manufacturer that does it,Cotic Road Rat was the only one I'm aware of but even they went to the conventional rear of leg position.
There maybe custom builders who'll oblige but I don't know of any mass produced frames.

If it were such a big problem the big US names would've done something other than through axle designed forks,which are a DH invention.
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Adnepos
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Joined: 15 Jun 2016, 1:47pm

Re: Front disc brake with dropouts

Post by Adnepos »

So I have kind of got to the bottom of this story of no secondary retention of my Dawes Galaxy front wheel.

The forks should be fitted with tabs. It isn't. The retailer has been both responsive and helpful but no longer has an arrangement with Dawes.

Dawes, despite a reputation for ignoring end-users, responded very quickly to my contact with them and will be posting out my missing tabs.

I don't know why these tabs were not fitted before the cycle got to me. Maybe lack of secondary retention is a widespread problem but in the grand scheme of things, blowouts and falling into potholes are an order of magnitude more of a problem.
Brucey
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Re: Front disc brake with dropouts

Post by Brucey »

Adnepos wrote: ....

Dawes, despite a reputation for ignoring end-users, responded very quickly to my contact with them and will be posting out my missing tabs.

I don't know why these tabs were not fitted before the cycle got to me. Maybe lack of secondary retention is a widespread problem but in the grand scheme of things, blowouts and falling into potholes are an order of magnitude more of a problem.


if they are 'posting tabs out to you' it sounds like they are this kind of secondary retention washer

Image

this will pass the standard secondary retention test but such devices are in no way suitable for resisting a disc-braked wheel which is busy trying to self-eject (IIRC the forces are about x50 different...). Arguably you might be worse off with such things fitted because there is one more interface at which sliding can start.

I would suggest that a safer solution would be to fit a replacement set of forks with substantial "lawyer's lips".

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
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tykeboy2003
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Re: Front disc brake with dropouts

Post by tykeboy2003 »

Adnepos wrote:I have a Dawes Galaxy (standard, not tandem) that came with disc brakes -160mm. I read with alarm that if the quick release (QR) mechanism becomes loose on these kinds of set-up, then front-braking can cause the axle to jump off the forks.

My front wheel comes off the forks readily when I loosen the QR-no lawyers lips or any other back-up.

I have had just one occasion when I noticed the front QR had come loose whilst on the road and I fixed it immediately! I've done close on 10,000 miles and the disc brakes have functioned well, no maintenance problems (they are cable actuated, not hydraulic) and not caused the wheel to move in the dropouts.

I'm now thinking of upgrading the front wheel, install a magneto for onboard electricity.

Should I be radical and get forks that take a thru' axle? A new fork would also have a 'self-connecting system' -the electrical contact is made when the wheel is secured in the forks, Schmidt SL. But my current forks have given no trouble so the additional expense may not be worthwhile.

What do you think?


Get some of these.

http://www.ebay.co.uk/itm/Trans-X-3-Pie ... AGfVaG2UHg
nez
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Joined: 19 Jun 2008, 12:11am

Re: Front disc brake with dropouts

Post by nez »

I'm not convinced these have any place on a touring bike. I have a Super Galaxy a couple of years older which came with cantis. I did upgrade the cantis at one point but set up right they work great. I don't know what part of riding a touring bike includes doing stoppies! On the other hand I have a Specialized Roubaix with disks and I love it - but it's a very different bike.
Adnepos
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Re: Front disc brake with dropouts

Post by Adnepos »

tykeboy2003 wrote:...Get some of these.

http://www.ebay.co.uk/itm/Trans-X-3-Pie ... AGfVaG2UHg


Now been supplied with and put on the 'tabs' but have also replaced the quick release system (front and back axles) with these Trans skewers. Thank you for the hint. I am happy.
mattsccm
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Re: Front disc brake with dropouts

Post by mattsccm »

Not denying that the wheel cannot come out but properly used a decent internal cam QR will stop it happening. Using it properly is the riders responsibilty and incompetence or ignorance is their own stupid fault. Millions of people use QRs happily with no problem. Lawyers lips are only there if you balls up. Surely everyone checks their bike? If not, tough luck.
The Cotic fork works in theory but doesn't half make the brake squeal. Maybe the design of brakes meant to face the other way creates vibrations.
Abradable Chin
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Re: Front disc brake with dropouts

Post by Abradable Chin »

Brucey wrote:A 100kg rider braking hard will manage 100kg at the contact patch which means a 200kg leverage load on the axle

I thought we'd mentioned on here before now that the maximum retardation that a cyclist can achieve is about 0.5g before involuntarily going over the handlebars?
Brucey
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Re: Front disc brake with dropouts

Post by Brucey »

Abradable Chin wrote:
Brucey wrote:A 100kg rider braking hard will manage 100kg at the contact patch which means a 200kg leverage load on the axle

I thought we'd mentioned on here before now that the maximum retardation that a cyclist can achieve is about 0.5g before involuntarily going over the handlebars?


it rather depends on the weight distribution.

I think if the 0.5G thing were true then the weight distribution that causes that would also mean that the slightest use of the brakes on a ~25 degree slope would result in you going over the bars.

cheers
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tykeboy2003
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Re: Front disc brake with dropouts

Post by tykeboy2003 »

Adnepos wrote:Now been supplied with and put on the 'tabs' but have also replaced the quick release system (front and back axles) with these Trans skewers. Thank you for the hint. I am happy.


No problem. I started using them when the original skewers wouldn't keep my front wheel straight no matter how tight I did them up (disk brakes might have something to do with it). Never had a problem since.
le.voyageur
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Re: Front disc brake with dropouts

Post by le.voyageur »

Any chance we can see a pic of the "posted out tabs" in situ please? they sound like an ideal solution.
Thanks
Adnepos
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Joined: 15 Jun 2016, 1:47pm

Re: Front disc brake with dropouts

Post by Adnepos »

Here's a photo of the Trans Skewer with the left-side tab sitting underneath the head of the skewer.
Attachments
skewer with tab.JPG
skewer with tab.JPG (34.82 KiB) Viewed 603 times
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