docbluedevil

Greetings from Colorado!

First post on this forum and appreciate all the great info here.

My wife and I have placed an order for our first tandem, a '04 Co-Motion Speedster Co-Pilot, through Mel at Tandems East. [So far, a great experience with Mel.]

We ordered an Arai drum brake for all of the mountain passes around us as well as for loaded touring. Mel had offered shaving the fins off the Arai brake with a lathe which would shave off about 6 oz. He said it would not affect performance and would cosmetically look good as well.

Anyone have any experience with this? I can see the pros regarding weight. Any cons? Anyone with pics? I've read a reference to this on the forum but have not found any in-depth info about it.

Thanks ahead of time.

Abe.

Gtscottie

I am not sure if shaving the drum is such a good idea. The reason for the fins is to dissipate heat outward caused by the friction of the brake shoe against the drum allowing the drum to cool quicker and give you constant braking power. If the fins are gone you may get over heated brakes, which will cause brake fade. I am not sure that 6 oz is that big of a deal unless you are planning on racing.

TandemGeek

You can read a typical discussion on the pros and cons of the shaved Arai drum brake by clicking on this link to the Tandem@Hobbes archives. https://search.bikelist.org/query.asp...MsgDate%5Ba%5D

This is a thread with 25 responses which cover the range of "opinions" and experiences. There is no general consensus and many suggestions that the weight savings are not worth the "potential" problems associated with overheating a shaved Arai. While there are certainly folks who have reported overheating an unmodified Arai -- smoking the drum and/or damaging the bearings in the hub -- conspicuously absent are any first-hand reported failures by folks who actually use the shaved drums. That doesn't necessarily mean failures related to drum shaving haven't happened; it just means no one has felt compelled to share the story if it has... but it is interesting that there aren't any such posts.

Ultimately, it probably comes down to this: If you are a lightweight team who is interested in having a drum brake for piece of mind the shaved drum will probably work fine. If you are a heavy team or a team that knows it's toting an extra 6oz around anyway and will use the drum for loaded touring why bother screwing around with it; it's only 6oz. Personally, I don't think the fins are all that effective as a heat sink but I'm not an engineer nor have I run the numbers; however, I have heard enough from the folks who are engineers and who have run the numbers to think they are of marginal value.

There is one other option for folks sitting on the fence and that is a rear disc. While not intended to be used as a drag brake, the rear disc does alleviate the problems associated with rim heating and is a nice brake option for lightweight, go-fast teams who occasionally find themselves in the mountains on a descent where they become a bit concerned about rim heating. Since the use of discs on tandems is pretty much in beta test mode I have previously recommended that folks consider having their tandems fitted with braze-ons for rim, disc, and drum brakes for the greatest amount of flexibility. I would note that Co-Motion will purposely not set up a tandem so that both a rear rim and disc brake can be used simultaneously to preclude the use of the disc as a "drag brake". I would also note that Mel was not fond of the newer Avid disc brake installations when we last were together at MTR '03.

There you have it. Personal experience? Both of our road tandems are fitted with hardware for disc drag brakes but have never bothered to use them. There have been a few occassions where I wish we had, if only for added piece of mind. We routinely ride with teams who have finned drums, shaved drums, rear disc drag brakes (old Hope models), Avid disc drag brakes, and Avid rear primary brakes. They all work as intended but the constant is that the discs and shaved drums are used by lightweight teams who do not place super-high demands on rear brakes. The heavier teams we ride recognize that they are kidding themselves to think shaving 6oz off of their total team/bike weight is even worth considering.

Here's a photo of a family we often ride with on their Triple from a few years back. It's not a great photo or very large but you can clearly see the shaved Arai on the rear wheel.

Michel Gagnon

As far as I know, Tandems East is the only one that offers the shaved drum. I do think the fins help a bit because they increase the surface of the drum in contact with air. The fins are not, however, as well designed as the fins present on some electronic equipment, for instance, so they are not as effective as they could be.

You recall, Mark, the discussion on drum brake failures. I would suggest that the lack of failures amongst shaved drum users is due to a few factors:
- limited number of users;
- the fact hills in the East are steep, but shorter than hills in the West.

The last factor might be one of the most important ones. I think that most "serious" users -- i.e. those that want to do a few West Coast mountain passes via back roads -- will either get a real unshaved Arai drum brake or will adapt their riding style accordingly and stop a few times to cool their brakes.

docbluedevil

Thanks for your input!

After reading the large thread, it sounds like the fins are used to help dissipate heat. If that's what they were created for, I'm gonna leave them as is. Plus, shaving the brake will likely void a warranty. I'm not into potentially compromising a vital mechanical system to save some a few ounces, especially with the mountainous terrain in which we live. I've never felt that I was in danger going uphill or on the flats; it's the descents that make me think about my mortality.

6 oz heavier and a ton safer,
Abe

Joe Voelkel

Well, let me be the first one to post about over-heating a shaved Arai drum brake.

It happened last summer, on the steepest hills of the Cabot Trail in Nova Scotia. I was riding a Co-Mo Speedster (shaving from Mel, of course, as well as a stoker-controlled lever brake). With my wife and about 35 lbs of rear pannier weight, our total weight sans bike was about 325 lbs.

We had to stop repeatedly to allow the brake to cool down. I'm not sure how hot those babies are supposed to get, but even with the water pouring down (the most beautiful scenery day = the fogged in, rainy, day -- go figure...) the brake was sizzling.

Eventually, an SUV from a group of people who were mixing riding and driving an SUV stopped, put the bike on the rear rack (yes, the tandem stayed safe!) and gave us a ride down the hill.

The same thing happened on the one big downhill on the next day, which was sunny. However, after the trip I took off the brake cover and cleaned the pads up--I have not had any problem with them this year in the Finger Lakes, which offers up some pretty steep hills.

Now, I wouldn't say for sure this was due to the shaving, but I own another tandem with an unshaved Arai, and never had this problem. Mel tells me he has gone down steeper roads with no problem, so maybe it was that particular brake unit. In retrospect, I wished I had put on a new set of brake pads for my rim brakes--they were about 3/4 done. If I were to do it again, I would take the unshaved route--shaving the brake must void the warranty.

swc7916

Why did you find it necessary to stop? Were the brakes fading or something?

R900

I like ours, although I want to swap it for a disk:



We've had zero problems, but live in Eastern Indiana, some hills, but nothing super long or steep. The brake as worked perfectly, and I do use it. I mainly got it because I was unhappy with the Avid canti's. That has now been fixed on the front with a new fork and a Shimano R600 caliper, I've tried some other rear, and currently run some old XT canti's, better but still not great. I think a disk would give us most of the benefit for the drum (for our region), and improve normal braking. A single disk should also save a fair amount of weight compared to the drum/canti combo.

I'm not as worried about the weight, the shaved drums just look a lot sleeker.

LWaB

Also Longstaffs in Britain.

LWaB

Our unshaved Arai gets sizzling hot on the longer hills too. If it isn't starting to fade, I figure it is just doing what it is designed to do, turn kinetic energy in heat.

Michel Gagnon

How were you using the drum brake ? Were you using it on and off with a brake lever like any other brake or were you applying it all the time to slow you down?

I don't have a shaved brake but nevertheless, I use it like a normal brake, going on and off.

sch

Judging from our experience on two tandems and a team weight of 380 or so with bike, any
prolonged braking will result in a LOT of heat. It would behoove owners to hop off the bike
at the bottom of a hill after braking from say 40mph to stop and check the temp of whatever
braking surface you have (except do not touch the disk!!). Our rear rim was too hot to touch
more than a few seconds on several occasions with braking from 35 to zero down a half mile
hill to my house. The rear disk on the new bike gets MUCH hotter. Drums would be intermediate
with the heat distributed over a larger mass, but long descents with drag set can be expected
to get the drum well above boiling point of water. A little experimentation ahead of time is
a good idea to get some appreciation for expected temperature rises.

merlinextraligh

IMHO, the only reason you'd want a drum brake is to help reduce overheating from high braking demand.

If you're braking demands aren't enough for heat to be a concern, you don't need a drag brake in the first place.

If your braking demands make heat a concern, I'd want my drum brake to dissipate heat as originally designed.

Joe Voelkel

A few of you have asked how I (really, my stoker) used the shaved drum brake that overheated on the Cabot Trail. Well, parts of the Cabot Trail have 12-15% grades, but let's just say 10%, and there are several sections where the roads wind in switchbacks. This produces a combination of steep hills and turns that demand that you slow down frequently.
My stoker was applying the brake constantly. Why? Because I was yelling "brake!!" while using my calipers (on and off) to slow down. If you've ridden down switchbacks, you also know that the steepest part of the switchback is when it makes that tight curve. So we'd be trying to slow down into that tight curve, but when we hit the curve we'd start speeding up again. It's not a good feeling to be going into a curve at speed and not being able to slow down enough to feel safe. (BTW, I'm not afraid to take a hill at 55 mph, as long as the road is out in front of me--but worrying about going off the road, with my wife on the back of the bike, is not my cup of tea.)
By the way, I have since gotten rid of the shaved brake drum and replaced it with an unshaved one. The new one was not perfect (the brake pads were not aligned enough when glued to the drum, so I had to shave off some of the pad (asbestos?) to get the pads to fit in the assembly.) I have had no overheating problem with those brakes -- we have used them in the Finger Lakes and the Adirondacks (some steep hills). We have had no heating problems with it (or with the earlier unshaved brake I had on a previous tandem). We have not used the unshaved brake with the extra 35 lbs of gear, but I don't believe that is what made the difference.
I'd say that if you plan to use your tandem on gentle 5-6% grades in the West, with gentle curves, a shaved brake (or even just caliper brakes) would be OK for most conditions. But if you'll be hitting 10-15% grades with arbitrary curves, I would definitely go with an unshaved brake.

mkane77g

There called a drag brake for a reason, used constantly while decending steep grades, to keep your speed in check. Try that with a disc.

Chris_W

My wife's family lives at the northern end of the Cabot Trail, so I know the road quite well and have done it on both our tandem and a single bike. We live in the Swiss Alps, so we also have something major to compare it to. IMO, none of the descents on the Cabot Trail should cause much worry about brakes overheating because none of them are long enough or twisty enough to cause much heat build-up. I'm therefore very confused as to why these roads could cause a problem for most braking systems, and they certainly shouldn't be causing a problem with an Arai drum brake (as reported above) unless the operator is doing something wrong.

The biggest hills on the Cabot Trail only involve about 400m of vertical descent - the longest continuous steep section would be the west side of North Mountain, where you drop almost 400m in about 4km, but there are no switchbacks on that part. In fact, the only real switchbacks on the whole trail are on the descent down MacKenzie mountain, which is maybe 300m of descent in 4km. Even those switchbacks are some of the most gentle and widest that I've ever seen and are a pleasure to roll around at speed on a tandem. There are a few tight turns at the bottom of descents where you're going down to a river crossing, and make a 180-degree turn when the turns at each end of the little bridge are added together, but the road is then flat again after that, and they are isolated rather than being in a series of switchbacks.

Our tandem braking setup is two rim brakes (V-brakes) controlled by the captain, plus a rear disc controlled by the stoker, which she uses to trim speed during straight parts of the downhill when I ask for it to give the rims a rest. Total team weight is just under 300lbs. When we went to Cape Breton last summer and were taking the tandem for the first time, I seriously debated whether it was worth bringing our rear disc brake for the trip (it adds about 500 grams to the bike weight), and based on my knowledge of those descents decided that it would not be necessary because they really aren't long enough. Here in the Alps, it is only when doing descents of around 1000 metres of continuous descending and that are steep and twisty that the extra rear disc really seems necessary, and that type of road is not easy to find. Of course, we use the disc on descents that are shorter and/or easier than that, but it doesn't really seem necessary except in the more extreme situations.

So, we did the whole Cabot Trail with just rim brakes and never had any overheating problems and never regretted not bringing our rear disc. In fact, my memory of the descents is that they were much easier than I was expecting them to be and compared to European Alpine descents, they were a piece of cake - the roads on the Cabot Trail are comparatively so wide, and they clear so much away from the sides of the road that you nearly always have a very far-reaching sight-line when entering each corner. You can therefore take most bends on the Cabot Trail at a decent speed with plenty of confidence, and so you don't need to brake as much when approaching bends as we would in Europe, where sight-lines tend to be much shorter, and so cornering speed must be reduced accordingly. Even if you were to trim a lot more speed before entering each corner, and you had a bit more weight than we do to slow down, I cannot imagine that any of the descents on the Cabot Trail could allow you to exceed the heat capacity of an Arai drum brake, regardless of whether it has shaved fins.

I think you need to come over to Europe to find out what a REAL descent is like, and what the actual heat capacity of your Arai drum brake is. I cannot imagine how you would reach this limit on the Cabot Trail.

Philly Tandem

Regarding "voiding the warranty" of an Arai, I'm guessing there isn't a warranty any more since they are no longer in production. They seem to be commanding pretty high prices on Ebay nowadays.

Over the years I've accumulated (or, "hoarded") 3-4 Arais in my parts box. I figure I'm set for a while longer, even with two big bikes to outfit.

Joe Voelkel

Thanks for the note, Chris. I'm guessing that one or more of these factors were at play in our ride down the Cabot trail:
1. Rain (with very heavy fog). Rim brakes were not working as well as they would have in dry weather. So more work needed to be done by the drum brake.
2. Arai brake was shaved.
3. When the brake got very hot (the outer (shaved) rim of the drum brake was way too hot to touch--but, of course, I did it anyway), we were concerned what would happen if we kept using it. So we waited on the side of the road for 3-5 minutes for it to cool down. But the pattern kept repeating. We probably stopped 3 or 4 times going down MacKenzie.

Now, as for what we were doing "wrong", I can't think of any explanation except 1 and 2 above. Also, with the heavy fog (we could see clearly only about 10 m before the fog took over--our real concern was that we would be run over by a car), there were no clear sight lines. Actually, the next day, coming down North Mountain (we traveled clock-wise), we had the same problem in good weather. For North Mountain (yes, really a long hill...) there is long relatively straight descent followed by a sharp left turn. That was tough for us as well. Here, back in the Finger Lakes (some steep hills), with the same bike but an unshaved Arai brake, we are fine.

I don't know what the grade was on MacKenzie, but were told some stretches were 15%-18% (no idea if that is correct!). In the Cyclist's Guides to Canada's Ocean Playground, Gary Conrod's says that a hill past North Mountain drops 365m in 3.2 km, but that North Mountain is the fastest descent on the Cabot trail (no elevation changes given)

I can't speak for the Swiss Alps directly, but if they are not a lot tougher than the Cabot Trail I will stop watching the Tour! We hope to visit your beautiful country someday.

Joe Voelkel

On off. But this was with a brake-lever type of control. We just switched last weekend to a bar con (bar end) shifter, which is more natural to set to the amount of drag you want, so you can put both hands back into a natural positions on the handlebars. I think I mentioned that the drum brake was stoker controlled?

Chris_W

It certainly sounds like rain and fog were the main factors causing your braking problems.

MacKenzie certainly doesn't have any 15-18% sections, maybe a few brief 10% sections, but most of it is a pretty constant 7-8%. North mountain has long stretches of 10-12% on both sides, maybe 15% on the inside of some bends, but not sustained. The steepest section on the trail is on Smokey, which gets over 15% in some corners, and is also above 10% for a decent length, but the total elevation change from bottom to top is no more than 250m, so it is not as hard as North, which is certainly the hardest on the trail (this is true when doing the trail in either direction).

Most of the climbs that the Tour de France guys do in the Alps average 6% or 7%, with only brief sections that are steeper than that (e.g., the first 4km of Alpe d'Huez is 9-10%, but then it eases off to 7-8% for the remainder). The climbs in the Pyrenees are known to be a bit steeper than those in the Alps, but I haven't done any in the Pyrenees. Steeper and harder climbs do exist in the Alps, but they tend to be on much smaller roads that the carnival of the Tour de France cannot easily negotiate, and so they are not used, which is a shame. The Giro d'Italia is much better in this respect. In general, many climbs in the Italian Alps are steeper than those in the French Alps, and the organizers of the Giro do everything they can to make it more of a spectacle, and so often include some seriously steep and challenging climbs. I therefore often prefer the Giro's route to the Tour's, because there are fewer boring flat stages, more mountain-top finishes, and the climbs are even steeper; the last couple of years the Giro has even had more time trials than the Tour. Unfortunately, it is only for the Tour de France that ALL the big guns come out to race, rather than there only being a subset of them at the Giro, which is what still makes the Tour the better race even though the route and the stages are not as exciting as in the Giro.

Anyway, if you have ridden up either side of North Mountain, then you wil have ridden 4 or 5 kms which are at least as tough as any 4 or 5km in the Tour de France in recent years (as far as I can recall). Racing at the speeds that the guys in the Tour do it (sustaining 20kph up 8% inclines, and putting in surges faster than that) and doing it day after day, and sometimes doing climbs that have a total height gain of 1,500m or 2,000m is what makes the race hard, but the difficulty is rarely caused by the steepness of the gradient in any individual km. Also, an 8% gradient at 2,000 or 2,500 metres altitude is noticeably harder than an 8% gradient at sea level (where the Cabot Trail is).

born2pdl

Another shaved drum review: Overheated.

315lb team weight, trek t2000, no cargo. We used it to descend after climbing a 1000ft pass near our home north of Salt Lake City. Don't know the grade, but steep and windy, not descendable on a tandem with no drum. I had my wife squirt it with her waterbottle every 15-20 seconds during the descent and the water crackled while hitting it. Used the whole bottle, bad hot brake smell. Luckily the only lasting effect was the anodizing on the hub is now slightly discolored. Bearings weren't damaged.

Haven't tried it with a stock drum. I enjoyed the challenge of climbing the pass on the tandem, but for self preservation we just don't tandem it anymore. Haven't bothered getting a stock drum, as we can take alternate routes to avoid the local steep descents.

No I would not shave the drum. The one odd time that you really really need it, it could let you down.