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Old 07-13-09, 11:16 AM   #1
mpesu
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Brompton: rear rim quickly worn out

Hi there wisemen,
I use a Brompton in Helsinki for every day commuting. Brompton is in use also in autumn & winter, which means that conditions are often quite rough. I've had the bike now for 2 years and I've driven it ~7000 km.

Now I found out that rear rim is almost worn out. The "groove" in the middle of the braking surface has totally vanished. Questions are:

1. Has the wearing been abnormally fast?
2. I've used koolstop grey pads. Are there some better pads available that do not wear the rim that fast?
3. How soon will the rim collapse (and how badly will I hurt myself when it happens)?

Thanks already for distributing knowledge.

Matti
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Old 07-13-09, 11:33 AM   #2
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1: 7000km is okay considering you've ridden it through winters. might have gotten more if you used the front and kept the pads and rims clean from debris build up.
2: a softer compound pad will save your rims at the cost of having to replace the pads more often.
3: the rim will likely crack down the worn area if it's really worn and you give it a good hit from a pothole on an under inflated tire.
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Old 07-13-09, 11:49 AM   #3
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2: a softer compound pad will save your rims at the cost of having to replace the pads more often.
Thanks. Can you suggest any pad brand that would enable longer life for my next rim.
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Old 07-13-09, 11:49 AM   #4
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Its likely any salt laid on the winter roads will have contributed to fast wear. Manufacturers are always cautious with wear lines etc but for your own sake I wouldn't leave it too long before changing the rim. When the wheel collapses you'll likely find yourself under a lorry.
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Old 07-13-09, 12:05 PM   #5
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the wheel won't collapse, that's more from giving it a strong impact to the rim under load.

what happens is that the rim will crack and sort of bulge out in the cracked spot, making your brakes rub. worst case, your rim cracks around the entire circumference and your tire falls off the rim, jamming into the brake pads.

softer compound pads... koolstop salmon.
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Old 07-13-09, 12:22 PM   #6
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softer compound pads... koolstop salmon.
Great pads those, but in the UK they can be hard to find in different patterns and shapes. You may be luckier in Finland. They made my Merc brakes tolerable. (old fashioned caliper style with poor mechanical advantage and pathetic stopping power).
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Old 07-13-09, 05:29 PM   #7
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The rear brakes and rim get dirty very quickly in wet conditions. You'll get more mileage if you stop using the rear brakes for normal slowing and stopping. Keep them for emergencies. I have started doing this after my rear pads wore out in just 2 weeks of wet commuting. It has made a fantastic difference.

[edit] Wow what a confusing statement. I meant use the front brakes for normal stuff and the rears only for emergencies.

Last edited by jur; 07-14-09 at 04:56 AM.
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Old 07-13-09, 07:12 PM   #8
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+1 on the Koolstop Salmons. Best to rinse the pads and rims after every ride I guess. That's what I do here when it rains and the grime builds up.
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Old 07-14-09, 07:43 AM   #9
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softer pads .. keep in mind that all too often small debris gets into the pads ( the softer the much earlier this happens) than you have some crap doing havoc to the rims.... you need to clean softer pads more often ...

general question and I throw this in to the round just as a brain teaser....
if the bike goes 20 miles fast the descent is 10 % the weight of the bike with rider is 190 lbs it takes ??????? how much force to slow the bike down .... ?
Now if we get the result of this and we find out that the force is " 100"

does this "100" change if we use softer or harder pads
the 100 could also be called friction which would give us an idea about the wear of the pads and the rim ....

does this 100 change ? ( I am not talking about the force you have to apply on the lever to come to a stop. that one will change dramatically with different pads , or brakes ..like a v brake or a centerpull, sidepull brake )

If we come to the conclusion that you need 100 friction to come to a stop than it makes no difference how soft or hard or good or bad your pads or brakes are .. right ?

( it might need superhuman strength to get to the 100 with nasty brakes though )

lets hear
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Old 07-14-09, 09:45 AM   #10
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Great comments from all, thanks.

The thing is, with Brompton's not that effective brakes and with the velocities it so easily goes, I can very very rarely affort to use only the front brake. I haven't managed to find salmon's from Finland, even those grey ones I ordered from ChainreactionCycles.

And one more thing now when I think this in more detail. It seems that the winter is actually not SO much responsible for the wearing. Major part of the wearing has occured after I installed those grey pads only few months ago. Maybe I'll ditch them first.

Last edited by mpesu; 07-14-09 at 09:52 AM.
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Old 07-14-09, 02:39 PM   #11
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Hub brakes
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Old 07-15-09, 12:57 AM   #12
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If you go to the Kinetics website you will find that they are selling off complete Brompton rear wheels that are surplus from their 8 speed conversion work, fifty quid a go, seems like a good price :-

http://www.kinetics.org.uk/html/spares.shtml
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Old 07-15-09, 09:51 AM   #13
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Pity that I have the 3-speed hub instead of single speed that they're selling at the Kinetics.
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Old 07-15-09, 06:39 PM   #14
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If I were commuting in all weather year round, I'd invest in a front hub brake. There are front hub brakes for the Brompton and you would use the rear brake for emergencies. I like the SRAM rear coaster brake on my Dahon Presto. I wonder why Brompton never used the SRAM 3 speed hub with a rear coaster brake? All you would need is a front brake and that only gets used on emergencies.
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Old 07-16-09, 01:28 AM   #15
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Anybody have clue about what brand front hub brakes have been used for Bromptons? The idea sounds feasible. In the most slippery conditions at winter one is still forced to use the rear brake more. Using the front brake on ice means a big hug to the mother earth.

What about disk brakes for Brompton. I saw images of a bike modified by SP. Do you know about the costs?

Last edited by mpesu; 07-16-09 at 01:44 AM.
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Old 07-16-09, 02:30 AM   #16
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Anybody have clue about what brand front hub brakes have been used for Bromptons?
Sturmey Archer
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Old 07-16-09, 02:10 PM   #17
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The front hub brake is made by Greenspeed.
More info and a picture ?
http://www.flickr.com/photos/plooifiets/3671516172/
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Old 07-16-09, 03:59 PM   #18
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Try telfon cables as the long cable runs on folders means that cable fricton is high. This might mean that your front brake works better so as you can take up "jurs" comments about avioding using the rear brake. Often with less cable fricton you can get away with a closer set up with out it catching when the brakes are released. I found that "swiss stops" pads were better than kool stops on the rear on my folder as less toe in resulted such a closer set up.

The alex? rims on Mezzo's have groves in them which may reduce the wear? if you can get some
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Old 07-16-09, 09:24 PM   #19
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The front hub brake is made by Greenspeed.
More info and a picture ?
http://www.flickr.com/photos/plooifiets/3671516172/
That's the hub! It must stop the Brompton very fast. Very nice. I wonder how much friction it adds to the front wheel?
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Old 07-17-09, 02:14 PM   #20
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That's the hub! It must stop the Brompton very fast.

It response in an other way than the original brake. Its not that sharp, more relax way. But it sure brakes.

I wonder how much friction it adds to the front wheel?


There was some discussion on the Yahoo Brompton forum. But until now (about 200 km's) I don't notice any problems.
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Old 07-17-09, 07:26 PM   #21
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I put a S-A front drum brake on my old Schwinn Cruiser and was dissapointed with its stopping power. Others I have talked with have expressed similar thoughts on these. Now the coaster in back works as well as good V-brake would but the back brake is always less effecive in stopping power.

My feeling is that the OP should be wearing out his front rim faster. Cleaning off the rims and brakes would likely add life but rim brakes will wear out rims, particularly in when the going gets gritty. Accept it and replace rims as items that wear, or go disks. A coaster for the rear is a good option with trade offs. You can't back pedal, bothersome at stops. Braking power is only optimal with pedals at the 3:00 and 9:00 clock position. Disk brakes are costlier and heavier.
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Old 07-21-09, 03:06 PM   #22
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I have a 26" wheel commuter bike (Carrera Subway 8) with Shimano 8-speed hub gears that also has Shimano roller brakes. I do not really understand how these work but they only need a squeeze of special grease once a year (must admit I have never got round to it ) and nothing ever wears apparently. In use they lack a bit of initial bite compare with v-brakes but stop well enough and are totally impervious to wet weather.
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Old 10-16-09, 04:26 AM   #23
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Then it finally happened. The same day I went to my sparepart dealer to get the replace rim, the original rim cracked. It didn't collapse or anything. Just a minor 3 cm long crack. I suppose, that if I'd continue using that rim, the crack would grow quite rapidly.
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