brakes for hill repeats
I asked in the Road forum but got dismissed by the zero-body-fat crowd.
what I want to know is the best braking plan for hill repeats. I'm a ~270 clyde training on a hill a mile or two up and with some 15% sections.
when I do this on my road bike with rim brakes, the rims are incredibly hot once I get back to the bottom of the hill. this seems dangerous, though I guess I could just tear through pads if I'm not doing great harm to the rims.
would disc brakes be better though? They are available on a lot of road-ish bikes.
Drum brakes might seem ideal though they have limited availability. Also, I did a 2-mile descent with a front drum and it sure squealed down much of the descent.
I would like to see the average grade on that climb. Honestly if most of that grade is over 10 with sections as you say up to 15, well that's really steep. I would also assume there are switchbacks on a road like that. Braking on a very steep, very twisty road at 270 lbs...I would say find another hill to ride.
however if the road really isn't that steep, and it's not that twisty, I think everyone is going to agree that modulation is the key. I live in the mountains and can't go in any direction from my house for any real distance without getting 1000 feet of climbing. I try to ride sections that aren't as steep without braking, and brake harder with both brakes just prior to a corner, I then try to stay off the brakes as long as possible before going back on. I don't ride the brakes, I am either getting on them hard, or off them all together.
here's Pack Monadnock: http://app.strava.com/rides/8081274. 11.9% average. indeed, one steep climb. but you need short, steep climbs to train for something like Washington.
that's why I'm asking about brakes
I believe disc brakes do better than rim brakes in situations like this. If your rims get too hot, you can blow a tire and that would be bad going down a hill. If it were me, I'd do disc brakes.
This is not to say that disc brakes are perfect...
I just did 50 miles with about 5000' of climbing. One of the hills has an honest 2 mile stretch with virtually the entire distance 10% or slightly greater. While I only weigh 200 lbs, I don't experience any brake fade whatsoever. This particular hill doesn't have switchbacks, but the pavement is very bad in stretches, so I'm periodically braking very hard. The Volagi has discs front and rear.
Originally Posted by cplager
can we have a bike that has both on the front, and you have some kind of double action breaking trigger :)
While an 11% average is certainly steep, 2km isn't very long and I would expect that good braking technique would be all that is required in combination with rim brakes to make it a safe descent.
There are two questions you need to ask yourself:
Originally Posted by mtalinm
- Are your brakes "fading" during the descent? That is: do you have to pull the lever harder and harder to achieve the same amount of deceleration?
- Is the rim getting hot enough to melt the tire rubber or to cause the air in the inner tube to expand to the point where the tube and tire will rupture?
If you're not experiencing either of these problems, you shouldn't have anything to worry about...
I have a hill like that around here I used to do repeats on and it had a stop sign at the bottom. I could hit 55mph pretty easy w/o tail winds then hit the stop sign. I would advice to save your knees and find a mellower hill. You will start to pedal sloppy after a couple rounds and it has more long term effects.
If you want to get a bike for just that hill then a CX bike with disc brakes will do IF you can find one and most will be in the 2k+ range. Another option is get a 29er hard tail with disc brakes and swap out the tires to some 28-32c slicks.
I have been on roadbikes on a lot of hills in the past and I have always thought that rim brake braking power was fine until I tried disc brakes.
I used to remember myself squeezing the brakes harder and harder as the rim brakes heat up; After a 10-15km (6-10 miles) 10-12 grade decents, my arms and hands would be hurting from all the squeezing. In wet conditions, it will be worse.
Now with hydraulic disc brakes, braking is definitely better even when it is pouring.
But before considering going all out with disc brakes, there are several improvements made into increasing rim brake performance which might be enough for your needs.
Perhaps replacing the brake pads with newer ones will improve performance. In higher end models, the cable pull is slightly different offering more power and control.
One of the best ways to keep the rim heat down is to alternate using front and rear brake, rather than grinding them both the whole way down.
I'm sorry, but, I can't agree with that. The back brake doesn't have nearly as much stopping power as the front. Pulsed braking, alternating between on and off, using both brakes is the most effective method to control speed, minimize heat build up and provide maximum cooling time, using a very rough approximate 60/40 front/rear split.
Originally Posted by ThermionicScott
But Fred,you are not coming to a full stop just scrubbing off some speed ,
so The braking alternation can be like an anti lock brake works,
a short pulse and you keep the rim from having heat to dissipate.
I highly Recommend stopping in the middle of a hill and having a Picnic.
Ah, I think I see the misunderstanding. I read Thermionic's post as suggesting one "alternate between" front and rear brakes. If he was suggesting the use of both brakes simultaneously, but, alternating between on and off. Then, yes, absolutely. We're suggesting the exact same thing.
If you don't use your brakes you won't have a problem. ;) Disk brakes are better but before you go to that expense make sure you have good brake pads (like cool stops) on are using the appropriate braking technique. If you go to disk brakes you will be better off just buying a bike made to accept them. Volagi was mentioned, Specialized and Colango and a number of others are coming out with new models. Be aware that you can smoke disk brakes as well if you don't use them properly. I know people who have melted the plastic parts off disk calipers and warped rotors.
I have mechanical disk brakes on my mtn bike and they are very quiet and brake smoothly. My commuter bike has vbrakes and I switched out the stock brake pads with salmon Kool stop pads and they stop extremely well in wet, cold, icy, snowy weather. They do squeal like crazy and that is probably my sole negative about salmon kool stop pads but cleaning the rims after dirty rides does help some.
Performance on hills wise, I live in Toronto and our big hills are few and far between. The steepest one I travel downhill on, I feather the brakes to avoid freaking out at the red light and to avoid heating up the rims. The rotors on the disk brakes also get hot but my rotors are 160 mm. I've read larger rotors take longer to heat up (or faster to cool down) but I don't have any experience with the 180 mm or 200 mm (are they available for road bikes?).
I used to commute a lot up and down the Berkeley Hills and up/down Mt. Diablo here in the Bay Area, CA. Yes, I had some pretty steep and continuous descents that did heat up my rims, but I wouldn't worry much for anything under 3 miles. I didn't brake that much. I do admit that the first couple of times coming down Mt. Diablo, the rims did get hot and I did get some brake fade, but I used to ride 700 x 28c minimum on most of my road bikes so there was plenty of room for a few psi increase due to heat. I'd often lower the pressure about 10 psi for the ride down. You might expect pressure to rise about 20% if the rims get really hot. Since all tires have some safety factor, and if you are 10% below the max on the front, then you're only going to be roughly 110% rated pressure by the bottom.
To avoid having to lower pressure, I used to do some pretty stupid things, like take a big squirt of water into my mouth midway down, place the water bottle back into cage, then on a straight section, I'd lean to either side and try to squirt water at the brake shoes in a tiny stream out of my puckered lips. It was foolish and not very effective even with a little amount of rushing wind (sort of like trying to imitate Bernard Hinault peeing off the side on a descent on the TdF). I used to think if just a few drops got onto the rim, it would prevent the rims from reaching boiling. But fact was, they never reached boiling point. Sure, they got too hot to touch, and spit would dry quickly, but no sizzling like when touching a hot iron.
Now, I never road many sew-ups with glue down those hills, so I can't speak for that. But most clinchers, I'd have to say, wouldn't have much problem.
thanks for all the suggestions about disc brakes. that definitely sounds like the way to go and has been what I was thinking.
it's possible that I could get by with rim brakes, but the rims are so hot at the end of a descent that I don't want to take a risk of a blowout.
new bike time!