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Old 08-24-12, 05:21 PM   #1
Earl Grey
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Brompton S-type - front brake cable rubbing

My shiny new S-type has a minor niggle - front brake cable rubs on the tire when turning right. No fenders, but I do have the little Al semicircle 'guard' attached to the fork which I believe is supposed to catch the brake cable and keep it off the tire / wheel.

However, the setup of the bike is such that the brake cable comes down out of the brake and then loops under the 'guard'. When turning the cable slips under it, and then makes contact with the tire. The cable routing goes from there, through a ring on the front half of the main tube and then to a second ring (actually attached to the front brake cable) which holds the other two cables together (it's a three-speed) in a bunch.

I think if the cable / housing had been cut about an inch or so shorter then the routing would be perfect (it seems to sit right if I pull a little more through the second ring toward the brake lever). I'm not sure if the bikes come already set up from Brompton or if the cables would have been installed and housings cut at the LBS I ordered through.

I can take it back to the shop for them to sort out, obviously, but if it's a fix I can make myself I'd rather do it. As I said, my guess is that cutting down the housing will solve the problem. Has anyone seen this before / have any alternative suggestions?
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Old 08-24-12, 07:48 PM   #2
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Yes, it should run on cable fender disk, not the tire.

http://www.sjscycles.co.uk/brompton-...isc-prod19069/

On my S (with stock cables, no fenders), it never rubs on the tire. The cable is supported in two places along the way, once by that plastic clip and the other on the loop, on the right side of the main tube.

Hope it helps.
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Old 08-25-12, 01:39 AM   #3
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maybe instead of the disc, make a wire guide, old spoke or a zip tie. ?
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Old 08-25-12, 12:10 PM   #4
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Thanks both!

Quote:
Originally Posted by fietsbob View Post
maybe instead of the disc, make a wire guide, old spoke or a zip tie. ?
Yeah, that's not a bad idea - I bet I could fix a zip tie so that it keeps the housing off the tire.

I'm assuming that the design is not fundamentally flawed though, so I'm also assuming that housing length is the root cause. There aren't really any other variables in the system - unless the housing can be bent around so firmly that it actually 'holds' a tighter radius out of the bottom of the brake and up toward the main frame
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Old 08-25-12, 05:44 PM   #5
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Housing is a big deal; in the manual, brompton says that the cables need to be within 2mm of the stated length.
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Old 08-25-12, 08:53 PM   #6
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Housing is a big deal; in the manual, brompton says that the cables need to be within 2mm of the stated length.
Interesting, thanks - I found the cable/housing datasheets. My part codes are FUXS (stop snickering) which means "front, 'reversed', S-type" and R+XS which means "rear, 'reversed', S-type". Front brake runs to the left lever, which I assume is considered 'reversed' - since the manual states that for UK bikes the left lever controls the rear brake.

So I do have the correct factory-sized housings for a left-front-brake setup, which suggests that housing length isn't the problem.
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Old 08-26-12, 09:54 AM   #7
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It's inconceivable, for someone living where it Rains,
to have bought the bike without the mudguards.

Though they put that braze on in the back side of the left fork blade,
to mount a disc guard
to have the cable not contact the tire.. for those that do..

There I'd use a loose loop around the cable, so there is no binding, around brake housing,
fitting thru that wee tube..
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Old 08-26-12, 10:52 AM   #8
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Inconceivable! http://www.youtube.com/watch?v=OHVjs...eature=related

Seriously, this is a highly portable bike for recreational city exploration on my (frequent) travels. If it's wet out I have no need or desire to be riding it. For a commuter, I'd agree that mudguards are mandatory.

I'll give your fix a try, thanks again for the suggestion. Although Brompton's clever engineering is a big part of the appeal of these bikes - there must be some way to get the 'factory' system to work. I can't believe this happens on every fender-less S-type.
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Old 08-26-12, 11:05 AM   #9
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Remember... In the City, that puddle may not be Water.
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Old 08-26-12, 11:07 AM   #10
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Remember... In the City, that puddle may not be Water.
Fair point...
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Old 08-26-12, 11:14 AM   #11
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Originally Posted by Earl Grey View Post
I'll give your fix a try, thanks again for the suggestion. Although Brompton's clever engineering is a big part of the appeal of these bikes - there must be some way to get the 'factory' system to work. I can't believe this happens on every fender-less S-type.
The stock solution works great on my bike. Never had a problem. Looks like you got a defective bike from the dealer. I would give them the chance to fix it.
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Old 08-26-12, 11:58 AM   #12
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Remember... In the City, that puddle may not be Water.
How do you know?

;-)
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Old 08-27-12, 07:24 AM   #13
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Originally Posted by alhedges View Post
Housing is a big deal; in the manual, brompton says that the cables need to be within 2mm of the stated length.
I have never seen the "stated length" in print anywhere - do you have a location where I can find these?
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Old 08-27-12, 10:32 AM   #14
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Somebody with a stock C should be able to mesure for you. Also a picture would help. If you would like to avoid going back to the shop maybe post a film showing the problem on Youtube and send them a e-mail with the link. Could be wrong lenght or just a minor problem but should not happen and they should fix it.
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Old 08-27-12, 12:11 PM   #15
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Yes, I am away from home now but will be back to the bike on Thursday and will post pictures then. Good idea.

If anyone with a 'reversed' setup S-type (i.e. left lever front brake) would care to post an accurate housing length I'd appreciate it.

I have no aversion to taking it back to the (very helpful) LBS people beyond the feeling that I really ought to be able to figure it out - just puzzled / curious.

I do wonder if housing (this is Jagwire L3) in general will take on a permanent set if bent firmly, or if this is inadvisable. I've never tried. It could be as simple as that to ensure a tighter radius that aligns the cable with the "cable fender disc"...

Anyway, I'll stop speculating until I post photos.
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Old 08-30-12, 01:46 PM   #16
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I believe I done figured it out.

Crawling around taking close up photos I realized that the 'reversed' front brake housing comes in two parts, one each side of the cable gatherer.

On this webpage, Brompton says that a reverse front S-type should have cable housing parts "FUXS" and "FL+S": http://www.brompton.co.uk/technical/spares/category.asp?q=B

What I've got is "FUXS" and "FL++", which is half the right housing for my bike, and half the right housing for a reverse front M-type. Not surprisingly, that is a longer cable.

If anyone with a reversed (left brake front) S- could confirm that they have "FUXS" and "FL+S" (the first code is by the lever, the second is a couple of inches from the brake assembly itself) I would be very grateful, but I'm pretty sure this is the problem.

If the LBS has them in stock I'll ask them to fix, otherwise order in and rig a temporary zip-tie.
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Old 08-30-12, 03:22 PM   #17
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I have a reversed S-type and FUXS and FL+S.
I would suspect few bike stores actually carry these parts - they probably just cut the brake housing from a bulk box to the appropriate length when replacing these housings.
Now, since Brompton expects them to be cut to 2mm accuracy, it would be nice if they actually provided the appropriate lengths.
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Old 08-30-12, 03:38 PM   #18
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Quote:
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I have a reversed S-type and FUXS and FL+S.
I would suspect few bike stores actually carry these parts - they probably just cut the brake housing from a bulk box to the appropriate length when replacing these housings.
Now, since Brompton expects them to be cut to 2mm accuracy, it would be nice if they actually provided the appropriate lengths.
Awesome, thank you! That settles it.

Yes, the LBS will probably just trim down the existing (since it's brand new) housing or fit fresh from the box. The mechanic I spoke to over the phone (it's 20+ miles so didn't want to make the trip without talking it over first) told me that they routinely do Brompton cable replacements with bulk housing and I get the impression it'll just be trial and error - so the folded and unfolded routing works.

I can't find the lengths stated anywhere.

Last edited by Earl Grey; 08-30-12 at 04:05 PM.
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Old 08-30-12, 03:46 PM   #19
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Quote:
I can't find the lengths stated anywhere.
Email Brompton and ask , they have some people to reply, in a couple days, usually..

Last edited by fietsbob; 08-30-12 at 04:15 PM.
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Old 08-30-12, 03:52 PM   #20
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Done, thanks for the suggestion.

Last edited by Earl Grey; 08-30-12 at 04:06 PM.
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Old 08-30-12, 05:13 PM   #21
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Quote:
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I can't find the lengths stated anywhere.
Yeah, I think all that they really say is that if you replace your existing cables, the length of the new cables should be +/- 2mm of your existing cables. And then they recommend you buy replacement cables from them, since they are already cut to the appropriate length.

I didn't realize until you pointed it out that they don't actually give the length.
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Old 08-31-12, 07:35 AM   #22
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Email Brompton and ask , they have some people to reply, in a couple days, usually..
Even better than a couple days, there was a reply waiting for me this morning. That's service!

Brompton apologized for the original build boo-boo, provided the length of FL+S (473mm, in case anyone is interested) and offered to ship the part direct to my dealer. Nice.
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Old 08-31-12, 09:55 PM   #23
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Fixed - cut down to 473mm (including the ferrule) and everything now works perfectly. Only had to remove about 3/8", if that, and the cable now runs perfectly. The handlebars even 'snap' into their clip when dropped to the fold position, which I swear they didn't before. I guess Brompton are serious about that +/-2mm.
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Old 09-01-12, 12:13 PM   #24
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Quote:
Originally Posted by Earl Grey View Post
Fixed - cut down to 473mm (including the ferrule) and everything now works perfectly. Only had to remove about 3/8", if that, and the cable now runs perfectly. The handlebars even 'snap' into their clip when dropped to the fold position, which I swear they didn't before. I guess Brompton are serious about that +/-2mm.
The Brompton is an intricate design with a lot of dependency between the various functionalities. For example, I removed the chain guard and now the front wheel hanger hit a rear spoke when I store the bike laying down. Or if you remove the seatpost when you fold (I do, cut the bottom flare) the bike does not lock.

This approach has pros and cons.
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Old 09-05-12, 04:04 AM   #25
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Quote:
Originally Posted by fietsbob View Post
It's inconceivable, for someone living where it Rains,
to have bought the bike without the mudguards.
Well, consider this... I ordered my S-type 2-Speed, titanium without mudguards and have been ridding it in soggy Britain for the last 3 1/2 years without any issues Oh and I love that film, such fun
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