Nomad2

Hi,
I am looking at purchasing a tandem to take part in cycling events with my soon to be 10 year old. I previously towed him in a WeeHoo iGo tag-along. Not looking at spending too much as we do most of our riding individually. I was looking at the Polygon Impression AX but there's a choice of V-brakes or mechanical disc. I was thinking of going the disc option thinking it would offer better braking without damaging rims, but I'm also wondering how complicated cable actuated disc brakes are to maintain. I have hydraulic discs on my mtb and my sons' bikes have v-brakes but I've never had anything with mechanical discs. Any thoughts would be appreciated.


thanks

nfmisso

Comes down to personal preference. I like rim brakes.

dabac

Unless you ride in really bad conditions, like sanded/salted roads, maintenance on mech discs is very similar to v-brake maintenance.
- adjust for pad wear
- pad replacement
- check and occasionally replace cabling
- eventually, replace rotors


Setting discs up to clear the rotor is different than getting rim brakes to clear the rim. Slightly more difficult due to the smaller margins. Not a big deal IMO

mtseymour

Your choice is less about maintenance and more about riding conditions and cost.

Mechanical disc brakes (eg. Shimano CX77, Avid BB7) are easy to maintain. The problem is that their performance is far short of hydraulic disc brakes on your mtn bike. Mechanical disc brakes tend to rub and are less powerful (eg., cable friction, single caliper, no auto-centering, no leverage from hydraulic system).

Which leads to your riding conditions. I assume that your team weight is less than 250 lbs, and that you're riding short distances (less than 25 miles) in mostly dry weather. For these conditions, the V-brake should brake as well (or better) than the mechanical disc with less noise and weight.

I'm not sure that it's worthwhile fro you to spend more on superior mechanical disc brakes (eg. TRP Spyre, TRP Hy/Rd).

Nomad2

Well, actually our team weight would be just over 250 pounds. The event we are aiming to do involves 7 days riding each of which can be up to 60 miles in whatever weather happens (it will be summer but can also be very wet at times). We have done the event the last 4 years with a tag-along (weeHoo iGo) which my son has outgrown. The last 2 years I was using an Mtb with hydraulic brakes and before that an old Mtb with v brakes. Managed OK then but my son was lighter then also.

Nomad2

Further to my previous postings on this thread, I'm weighing up my options like this:
I don't want to go with mechanical discs as it introduces yet another type of braking system we don't have on any of our other bikes as a family. I'm a bit concerned about how to keep them working optimally. So I'm thinking of either going with the V-brake option or converting the mechanical disc version to hydraulic. I'd much prefer the hydraulic brakes but it might be a bit of overkill for the application I've described. I'm keen to hear of the experiences of anyone on whether v-brakes will suffice.

dsmyers

Don't overthink it. I've toured on loaded tandems with adult stokers with cantilevers and been totally fine.

hermanchauw

Not tandeming but cargo biking.

I started with mechanical discs (BB7 then Giant DA8). Fair stopping power. Not impressive. Got sick of adjusting pad clearance every 1-2 weeks.

Then i switched to hydraulics (Shimano M447). Impressed with the stopping power, modulation and lack of maintenance. But got disappointed when the front developed sponginess and stuck piston after 2 months of use.

I am going back to v brakes. Never had lack of stopping power from them. Adjustment is much easier (less sensitive and frequent) than mechanical discs.

But this time i'll go for extra long (130mm) v brakes and 4 finger levers and see how it goes compared to standard ones.

I know i have to replace the rims some time in the future, but the frequency is much less than adjusting mechanical discs.

After what i experienced, i think there is a place for (mechanical) discs: drag brake. Use disc for long(ish) descends to keep speed in check. Use v brakes with much less maintenance most of the time.

OneIsAllYouNeed

All else being equal, V-brakes or cantilever brakes are better suited for use on a tandem than disc brakes. In my tandeming experience, the maintenance and adjustment intervals are much longer with rim brakes than discs.

Normal braking power is about the same with properly set up V-brakes, cantilever brakes, or cable-actuated disc brakes (assuming 200or 203mm rotors). Extended braking on long descents challenges most braking systems. Without a third brake, the best option for long descents is probably V-brakes with *heavy* aluminum rims. You can read several threads about tandems overheating brakes.

In my mind, the advantages to using disc brakes are:
-more rim options -- especially carbon rims, really wide rims, or aero rims
-multiple tire sizes on the same bike -- i.e. for swapping between 700c x 32mm tires and 650b x 52mm tires
-rims stay cleaner
-rims last much longer

In my mind, the disadvantages to disc brakes are:
-higher upfront cost
-frequent rotor truing
-you can expect to hear "tink tink tink" for 30 seconds after most stops

Leisesturm

Taken to the reductio ad absurdum, a V-Brake is a disc brake with the wheel rim being a surrogate disc. A rim actually makes a very effective and efficient braking surface, everything else being equal. If a 180mm disc is better than a 160mm, and a 203mm disc better than both of those, where do you think a 700mm disc rates... ... whoa... thing is, everything else is not always equal. Rims go out of true, heat absorbed by the rim will be transferred to the air contained in the innertube, and the proximity of the lower run of rim to mud, standing water or snow introduces inefficiencies that the much smaller disc does not experience. However, for the application the o.p. is considering, I can't see any of these things applying. IMO projected usage the o.p. describes almost screams for a Trek T900. With new saddles, and possibly an upgrade of the stock V-brakes to something like a pair of Shimano LX-V, they would have something comparing quite favorably with a Co-Motion Periscope! Periscopes are around $2500. New T900's were $1000. Now that they are discontinued they should be even cheaper. We are loving ours, bought at full list last year July 4.

joelcool

We rented a tandem several times with rim brakes, and they scared me - marginal stopping power and noisy. From reading the above, they obviously were not set up correctly.


As a result of that experience when selecting a tandem to purchase, I wanted disc brakes - didn't really care if they were hydraulic or mechanical, and ended up with mechanical disc brakes. Bottom line is I love these brakes. They are powerful, easy to modulate, etc.


It should go without saying but the brake load of a tandem is a lot higher than on a single.

merlinextraligh

Having ridden tandems with cable disc brakes, and rim brakes, IMHO there's not much of a difference in stopping power or ease of modulation. Cable discs may require a little less hand pressure for the same stopping power (hydraulics definitely require much less).


The big case for discs on a tandem is heating the rim and blowing off tires. Hot weather, heavy team, steep, long descents, blowing off tires from overheating can be a real issue, particularly if you're on the brakes a lot to limit speed descending.


If you're going to be doing long descents and brake a lot, I'd go for discs. Not a lot of descending, smaller team, or like to descend fast only braking for turns, not to limit speed on straights, then rim brakes are fine.

Pridedog

I have mechanical discs on my tandem that I ride with my grandchildren. (Cannondale T 2) I have had other tandems with rim and even hub brakes. The discs are far better in my experience. I have owned the T2 for 3 years and have not had to adjust the pads or true the rotors. Like everything it comes down to personal preference.

Nomad2

Thank you to everyone who has responded so far. The difference in price of the disc (mechanical) and non-disc tandems I'm considering is $200AU and my LBS can modify the mech. disc version for hydraulic brakes for another $300AU. On the first two of these events I towed my son on, I was using an MTB with V-brakes. This included wet and dry conditions, and at times very hilly. This included a descent through 1000m altitude (that one was in the dry). I managed fine, though the next two years using an MTB with hydraulic discs was certainly better. The combined weight of the equipment will be less with the tandem but the overall weight (given the stoker's growth!) will definitely be more. Not sure what, if any, difference there is in braking performance between a tandem and a bike with a tagalong. Hmmm, decisions, decisions.

Nomad2

Further to my original posts, I have found out the disc version of the tandem has 160mm rotors. Is that too small for a tandem? Does it diminish the benefits over V-brakes, even if I convert to hydraulic? I do have some arthritis in my thumb joints (not too much of an issue at the moment), so the hydraulic disc conversion had some attraction, but not if there's not sufficient benefit. Any thoughts?

OneIsAllYouNeed

Santana's "test reports" recommend 254mm rotors or larger. Many of us have had success with 203mm rotors. I, personally, wouldn't use a rotor under 200mm on a tandem.

StephenH

I've got 3 or 4 bikes with disk brakes, I like them, but there's not a whole lot of reason to use them or to avoid them for most riders- that said, I did pay an $80 upcharge to get disk brakes on the tandem several years ago when I bought it.
All my bikes have used BB5's or BB7's. BB5's can get to be a pain, BB7's are fine, and I don't know anything about any of the others.