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Discussion Starter · #1 ·
Hey guys, I'm new to te bike packing/ touring scene and I am buying myself a new steel frame to build for the tour across America I will be venturing on next year. I want to put some avid bb7 brakes on the bike and I want to know what size rotors to get. The frame I will be building on Will either be a tout terrain grande route from Peter white cycles or a Gunnar grande disc. I'm thinking 160 on the front and 140 on the rear? What size rotors do you guys use in your disc touring rigs?
thanks,
Chris
 

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Lord Thunderbottom
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I think it's going to depend on your weight and type of touring, based on the bikes listed I'm assuming road touring

If you're under clyde size 160/140 sounds fine, I run that size on my road/cross bike, I'm 240# so if you're close to that with the bike loaded there shouldn't be issues

I'd go 180/160 or 180/180 for myself, looking at 300#+ loaded up
 

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Discussion Starter · #4 ·
We'll I'd like to keep the weight of my gear at around 40-45 pounds via my ortlieb bags. I way 190# so total it would be around 240 give or take with some if the other misc gear.
 

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When you have 240 pounds on the bike I wouldn't worry about the weight difference between a 160mm rotor and a 140mm rotor. I have 160s front and rear on my cross bike with BB7s and I think that they work great. If I was going to be carrying extra weight I might want to have 180/160 because I like the front to have a little more power with the same pressure, but BB7s are really adjustable for how they feel at the lever so it can be done that way also.
 

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Discussion Starter · #10 ·
180/160 for my off road rig. I'm sure you'll be fine with 160/140 but 160/160 makes more sense per bsieb rotating comment.
ok I think that I'm going to go with the 160 160 front and rear. Should I be looking at the bb7 road calipers or the mtb?? I mean everything I'm putting on it with the exception of the shifters bar and stem is for a mtb.
 

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I'm in...
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Are you doing a flat bar or drop bars? I think that depends on the type of brake levers you're using? I had a set of BB5 road calipers for my buddy along with so Avid FR5 levers and they did not work as well as the BB7s MTB, I think it has something to do with the pull. I only deal with mountain bikes so maybe someone with a touring rig can help you with this question.
 

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Discussion Starter · #12 ·
Are you doing a flat bar or drop bars? I think that depends on the type of brake levers you're using? I had a set of BB5 road calipers for my buddy along with so Avid FR5 levers and they did not work as well as the BB7s MTB, I think it has something to do with the pull. I only deal with mountain bikes so maybe someone with a touring rig can help you with this question.
i will be setting it up with salsa cowbell 2 drop bars and some trp retro levers or cane creek levers.
 

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Discussion Starter · #14 ·
Ok i will be getting the 160 rotors for the build!! And also I will be getting the bb7 road version. I just read up on the accidents people have when they try to use mtb disc brakes on the road.
 

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My touring bike (Salsa Vaya) came with 160s front and rear, BB7 Road. I'm 190lbs, and I thought it sucked; barely enough braking power with zero luggage on the bike. Upsized to 185mm (just a rotor and mounting bracket change) and MUCH happier. I can do a stoppie now, that was plainly impossible before.

Fortunately, if you go with the 160 front, it's not hard to change. Just a bit of wasted money
 

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I run 203 front 180 rear on my dirt touring rig. I weigh 220 and tour where carrying lots of water is often required, so a heavy load. But in my experience with the 203 up front there's no harm in overkill when you don't need it; but when you do need it, like on a long, steep fully loaded downhill, you're damn glad you have it.
 

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I would put on the biggest rotors you possibly can for the heat dissipation if you intend on doing a reasonable amount of road touring. Road descents tend to be a lot faster and in many cases a lot longer than off road / trail type stuff. My buddy completely glazed a set of 140 / 160 with BB7 roads and resin pads on one 15Km descent last year in Indonesia his entire set up was less than 250lb. He reckoned it was really sketchy; he was glad that there was no traffic and no sharp bends in the lower section of the mountain.
Sintered pads also help a lot in keeping the the heat off the rotors; you don't have to worry about heating the callipers and boiling the brake fluid with mechanicals.
 

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I would put on the biggest rotors you possibly can for the heat dissipation if you intend on doing a reasonable amount of road touring. Road descents tend to be a lot faster and in many cases a lot longer than off road / trail type stuff. My buddy completely glazed a set of 140 / 160 with BB7 roads and resin pads on one 15Km descent last year in Indonesia his entire set up was less than 250lb. He reckoned it was really sketchy; he was glad that there was no traffic and no sharp bends in the lower section of the mountain.
Sintered pads also help a lot in keeping the the heat off the rotors; you don't have to worry about heating the callipers and boiling the brake fluid with mechanicals.
How you brake is as important as what equipment you use.

If you apply a bit of constant braking force over a long duration you generate much more heat relative to apply a higher braking force and then letting go of the brakes. Then applying them again. You can alternate front to back.

A German MTB magazine tested the heat capacity of various disc brakes and they were able to make every brake fail due to over heating. You can literally melt the plastic parts on your Avid mechanicals for example and warp the rotors.
 

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I know what your saying and agree but my point was that even braking properly loads and long road descents are hard on disc brakes - they never get chance to cool down fully before you're back on them, especially when you are dealing with switchbacks at the top and the like and then in to fast sweeping corners(40 to 50 mph) then taking off 30mph to hit some bends - the brakes don't get the chance to cool down hence the heat is always building.

Bigger rotors do help as they generate less heat (higher torque at the wheel so less friction required) and they have a bigger surface area to dissipate that heat. Keeping the system as cool as possible is a good thing
I was on canti's, tungsten carbide treated rims, Swissstop Blues and 50lb more; didn't have an issue.

To be honest I am yet to be fully convinced whether any disc brakes has been proved for road touring or tandem use as yet - but am about to try on my new build.
 
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