Biking: Catch-all

Minarchist wrote:

It's funny: I don't consider myself particularly small, but I guess at 5'10" and 172 pounds I'm on the smallish end for recreational cyclists in the area. Most guys would pass me on the downslopes and flats due to greater mass and power, but then I'd pass them again on those nasty climbs. Weird to pass someone when you yourself can only manage 7mph. Haven't seen so many people unclip and hoof it on such a big organized race in...well, ever.

That was my last tri. There was one guy who I must've passed 10-15 times during the 56 mile bike leg - I'd get him on the climbs, but he'd take me on the descents.

Incidentally, I've always found that I pick up speed faster than most other athletes in races on a downhill. At 5'8" and 170lbs, I'm certainly on the stockier side for triathletes, but is that all there is to it, or is it more to do with the finer points of bike selection, rider position and skill?

Who's the forum bike physics expert?

Jonman wrote:

Incidentally, I've always found that I pick up speed faster than most other athletes in races on a downhill. At 5'8" and 170lbs, I'm certainly on the stockier side for triathletes, but is that all there is to it, or is it more to do with the finer points of bike selection, rider position and skill?

TBH I was often descending as fast as any of them (hit 50mph for the first time ever! exciting! somewhat frightening!), but since I didn't know the roads and was riding on old brakes I was playing it a bit more cautious. The flats was where I was really getting pummeled. I could hang onto the back of a line for a mile or two at 22mph, but I just couldn't maintain that level of power with the crosswinds we were getting and still have anything for the climbs. I've got a great aerodynamic tuck, but I was taking downhills on the hoods just to not get too out of control. Wet roads + leaves + bad brakes = bad times for Minarchist.

ianunderhill wrote:

A) You live in the Land of the Fatties

FTFY

B) You happened to be passing a whole lot of wankers who don't know how to properly use their damned gears/think they're bigger men than they are.

Would you say you're more of a spinner or a masher, Minarchist?

I used to be a masher, but I've converted into a spinner the last few years, trying to maintain 80-90rpm regardless of the terrain. I gotta say, though, with only an 8-speed cassette in back (compact front), I was really reaching for one more gear on a few of those climbs, which has not happened to me in years. Some of the guys had lower ratios than me and could spin a little faster while still going slower, but some were definitely barely turning the pedals over. Had I a lower gear I would have spun more on those hills and probably had an easier time with them.

What does this year's Tiagra groupset go for right now?

Well, Minarchist, as I'm a whole inch taller than you and around the same weight when I'm not scary-light from medical procedures, I'm inclined to think either

A) You live in the Land of the Giants

Or

B) You happened to be passing a whole lot of wankers who don't know how to properly use their damned gears/think they're bigger men than they are.

Would you say you're more of a spinner or a masher, Minarchist?

Jonman: I'm not the physics guy by a longshot, but... I'd ask you how ballsy you are on those descents and how solid your handling skills are. It could very well be that you're not hitting the brakes as much as some more lily-livered triathletes and/or are holding/taking a better line than they are. It's important to remember that plenty of triathletes favor the run or the swim over the bike, and due to lack of confidence and or/skill, can't lay off the brakes, weave all over the road, take wider turns than necessary, etc.

I survived the Gran Fondo on Saturday! I rode solo most of the way since I didn't go in with any friends riding the same distance, and I did not get a lot of practice in, so the ~71 miles with a full mile of climbing (ow) was something to survive rather than conquer. Still, I'm pretty happy with a rolling time of 4hrs 4min for my current shape and that level of vert.

It's funny: I don't consider myself particularly small, but I guess at 5'10" and 172 pounds I'm on the smallish end for recreational cyclists in the area. Most guys would pass me on the downslopes and flats due to greater mass and power, but then I'd pass them again on those nasty climbs. Weird to pass someone when you yourself can only manage 7mph. Haven't seen so many people unclip and hoof it on such a big organized race in...well, ever.

EDIT: that should be 4 hours 40 minutes. That would be quite a speed for that terrain.

Minarchist wrote:
Jonman wrote:

Incidentally, I've always found that I pick up speed faster than most other athletes in races on a downhill. At 5'8" and 170lbs, I'm certainly on the stockier side for triathletes, but is that all there is to it, or is it more to do with the finer points of bike selection, rider position and skill?

TBH I was often descending as fast as any of them (hit 50mph for the first time ever! exciting! somewhat frightening!), but since I didn't know the roads and was riding on old brakes I was playing it a bit more cautious. The flats was where I was really getting pummeled. I could hang onto the back of a line for a mile or two at 22mph, but I just couldn't maintain that level of power with the crosswinds we were getting and still have anything for the climbs. I've got a great aerodynamic tuck, but I was taking downhills on the hoods just to not get too out of control. Wet roads + leaves + bad brakes = bad times for Minarchist.

Aye, too right. I'm a big pansy when it comes to descending at speed too

I hit about 46mph on the final screaming descent in my last race, and it was terrifying, as well as about 8mph faster than I ever been on that bike.

Good terrifying, but terrifying nonetheless. I managed to keep enough courage together to stick it out on the aerobars, but holy hell did I feel unstable and wobbly.

Minarchist: 10 speed Tiagra can be had for just north or south of about $600, IIRC. I'd pony up for nicer brakes, though.

Jonman: If you were accelerating faster than the other folks, you were still accelerating faster, so you're a) less a wuss than them and b) who knows? I'm not about to speculate about power output or aerodynamics, but to me, anything above 30mph on aero extensions can be damned scary, thanks to being away from the brakes and the limited turning radius of most tri bikes. I'm happy I just work on tri bikes and don't race 'em.

EDIT: Come to think of it, being aero on a descent vs riding the brakes would be a simple answer and probably account for a lot of folks, particularly on a steep descent out on the west coast.

ianunderhill wrote:

EDIT: Come to think of it, being aero on a descent vs riding the brakes would be a simple answer and probably account for a lot of folks, particularly on a steep descent out on the west coast.

True. Most of the folks I'm passing are also riding aero though.

Maybe I'm wrong, but I do feel like I've noticed me picking up a lot more speed in a non-pedalling descent over folks in front of me. Could be that I'm getting a drafting benefit or a better aero position that cuts my drag over them. Could be that it's confirmation bias and it's all in my brain. Thing is, most folks I'm racing against are on fancier, better maintained bikes than I am, which would suggest that their ride has a better aero-profile than mine. Mind you, rider position is a bigger contributor to drag than the bike itself.

I guess the question i was asking is "if I strap 50lbs of weight to me, then go down the same hill in the same aero tuck, will I go faster?", to answer Min's assertion upthread that skinny dudes descend slower.

Maybe you just pump up your tires more?

I did some internet research on this topic (science!), and it seems that there is some evidence to bear this out. Of course in an ideal world all weights would descend equally, but let me know when you get to Ideal, USA Pop. 1. Anyway, general theory is for a few reasons, mainly that greater mass helps maintain momentum through all mitigating factors, mainly wind resistance and to a lesser extent friction. Wind resistance is generally considered to scale linearly with the area intercepted, a 2-dimensional space; but mass/weight goes up with the volume of the object (generally), a 3-dimensional space. So if wind resistance is a square measurement but mass is a cubic one, the larger shape should have an advantage. Additionally, the added mass will help keep momentum over tire friction.

There seem to be plenty of anecdotal reports of this being the case, and I can't find any that seem to prove the opposite. But who knows? Maybe Jonman rides around on 700x23c at 110psi and everyone else is at 60.

Double.

Minarchist wrote:

Maybe Jonman rides around on 700x23c at 110psi and everyone else is at 60.

The funny thing about tire pressure is things have swung the other way the past few years, after many long decades of "max 'em!" maxims re:pressure and "narrow is best!" edicts re:width. The basic theory is that lower tire pressures reduce rolling resistance. Think of it in much the same way as a 170-180lbs rider would favor 110-115psi over 120psi - at 120psi, every little deflection in the pavement becomes something the tire bounces off of on impact, while the lower pressure allows the tire to deform slightly and roll over it. While there are diminishing returns on this (at some point, too little pressure means you need to work harder), pro riders have been going even lower than all this due to the benefit gained from a slightly increased contact patch and greater traction. In less common rough road races, this extends really low, as covered in this VeloNews item on this year's Paris Roubaix - indeed, this year's winner, Tom Boonen, reportedly ran 27mm-width tires around 59 and and 60psi, front and rear respectively. Even in a substantially less bumpy race, things are skewing wider and lower pressure - many riders in this year's Giro d'Italia were running 25mm tires at pressures in the 80s and 90s psi ranges.

I don't have good numbers handy, and as mentioned before, I don't have the grounding in physics to talk it out properly, but if you reason your way through it, it makes sense in a way. If we're lowering tire pressure for wet conditions, or we're favoring tires that are more supple and flexy and compliant for race day, and we're consistently noting benefits, there's a point at which increasing contact patch must result in a gain. Of course, we're also adding wind resistance, and with a wider tire, more weight and more wind resistance, but the 1-2mm gaps in tire widths afford us a lot of room to play with things without adding very much weight, and slight changes in aerodynamic properties are negligible until which we reach higher speeds, at which we have products that provide bigger net benefits than skinny-skinny tires, such as wheels and helmets and frames. Look at Zipp and HED wheels leading the aero wheel market - while their actual aerodynamic solutions are different, both have wider rims these days, to the point where, on carbon clincher wheels, some 23mm tires are fitting and flattening out more like a 24 or 25mm, and yet this isn't detrimental to the aero benefit of the wheel.

Of course, someone's bound to jump in and scream about trends and fads and companies trying to sell stuff - hypothetically, of course; no one here is that big of a stick of the mud. But whether you're riding to win or commuting or touring or just going for a cruise, experiment with your tire pressure some more if you haven't. Be leery of the Roubaix stuff, as those pros are running tubular (sew-up) tires at those insanely low pressures and thus aren't risking pinch flats, but on your road clinchers, try dropping a good 10-15psi off your current pressure if you run 700 x 23-25mm tires; 28-32mm, maybe as much as 25psi; 35mm+, maybe even a bit more. Take care to account for other factors, like your overall fitness and rested-ness as you're going through the process, but you might just find that sweet spot where life on the bike gets a little easier. Although do remember, there are diminishing returns after a point, and your inner tubes remain porous, so you still need to re-pump your tires at least weekly (if not more, as you go higher; thanks, osmosis!) to stay at your chosen pressure.

ianunderhill wrote:

Here, I'm a fan of the Kurt Kinetic Road Machine first and then the CycleOps Fluid2 as a close second.

So I went ahead and ordered one of these since I had a 20% off coupon expiring at REI (plus free shipping to their stores) Hopefully it'll keep me somewhat in shape over the winter.

ianunderhill wrote:

The funny thing about tire pressure is things have swung the other way the past few years, after many long decades of "max 'em!" maxims re:pressure and "narrow is best!" edicts re:width. The basic theory is that lower tire pressures reduce rolling resistance. Think of it in much the same way as a 170-180lbs rider would favor 110-115psi over 120psi - at 120psi, every little deflection in the pavement becomes something the tire bounces off of on impact,

No problems here at 28 PSI!

Norfair wrote:
ianunderhill wrote:

Here, I'm a fan of the Kurt Kinetic Road Machine first and then the CycleOps Fluid2 as a close second.

So I went ahead and ordered one of these since I had a 20% off coupon expiring at REI (plus free shipping to their stores) Hopefully it'll keep me somewhat in shape over the winter.

The KKRM is an awesome machine. Super happy with mine. It's getting to be the time of year that I'll be putting serious miles on it and my new treadmill. Might splurge for a new heavy bag too.

Jonman wrote:

I guess the question i was asking is "if I strap 50lbs of weight to me, then go down the same hill in the same aero tuck, will I go faster?", to answer Min's assertion upthread that skinny dudes descend slower.

You will. I'm 240 and pass my lighter friends going downhill, at least I do now that I have a decent bike. And my friend who's 270 passes me every time.

Wait, so are we saying the 15% drop rule is bunk? I'm guessing not, since wider would naturally lead to lower pressures there. Boonen's 60psi would equate to a bit over 80psi on 23cs, which for the crazy cobble road of Roubaix seems pretty reasonable. Not going to fault anyone for running wider tires on that nonsense. Wouldn't be surprised to see someone out there on knobbies in a few years.

LiquidMantis wrote:

No problems here at 28 PSI!

MTB heathen.

Minarchist wrote:

Boonen's 60psi would equate to a bit over 80psi on 23cs, which for the crazy cobble road of Roubaix seems pretty reasonable.

Yes, a perfectly reasonable reason why I shouldn't write long posts about bike stuff after a frustrating day of medical crap and while still on heavy painkillers. I even mentioned lower pressures for wider tires elsewhere, but I wasn't here, and nowhere did I mention the notion of pressure relative to tire volume, which is essential to think about if all this lower pressure talk isn't something you've seen before.

I mean, sure, you got it all just fine, but man, I wrote like sh*t, even for an off-the-cuff post. I am not on my game.

As for knobbies at Roubaix, I don't think they'd be very effective, as there's not much soft ground in the course. It's a lot of bad pavement and stretches of cobblestones, and let's not forget how skittish they'd be for the velodrome finish! Of course, as the road disc brake trend ramps up, and if UCI approves them, someone somewhere is bound to push some minority-knobbed thing on their sponsored team just because there's clearance. Remember suspension forks on road bikes at the Tour in the 90s?

No worries. I just want to know if the prevailing wisdom has changed, so that I can alter my actions accordingly.

And the knobbies thing was just a joke.

Minarchist wrote:

Maybe Jonman rides around on 700x23c at 110psi and everyone else is at 60.

Jonman rides around on 650s, usually at 100-110psi, although that race I was rocking around 80psi because I screwed up replacing my rim tape right before the race, which meant that one of my spoke holes wasn't fully covered, and I popped a tube pumping it up in the transition area right before the race.

Led to some last-minute panicking, and a jury-rigged repair using sticky-tape to try and boot the hole. Thankfully, it held during the race.

I usually pump right to 100psi. The calculator says my 23s should ride at 98, and I figure after the small bit of blowback from the presta release I should be right there.

Minarchist wrote:

I usually pump right to 100psi. The calculator says my 23s should ride at 98, and I figure after the small bit of blowback from the presta release I should be right there. :-)

I'm jumping around pumps. Got a cheap Nishiki at Dick's and it was near-impossible to pump past 90 p.s.i. Returned it and picked up a Topeak Joe Blows from Performance. Haven't tried it yet. Anyone have good lower-end pump recommendations?

Also, where's this "calculator"? Guess I could hit Sheldon Brown's site or my book, but I'm lazy!!!!

muraii wrote:

Also, where's this "calculator"? Guess I could hit Sheldon Brown's site or my book, but I'm lazy!!!!

This one is the most common one I've seen used. It basically codifies the 15% rule. Don't forget to add the (approximate) weight of your bike into the weight measurement, and then divide by two for the single-wheel weight. I don't really go for the different front/back inflations, but maybe I should try a 45/55% split just for kicks. I tend to think my weight is pretty evenly distributed, since I'm male and somewhat top-heavy.

muraii wrote:
Minarchist wrote:

I usually pump right to 100psi. The calculator says my 23s should ride at 98, and I figure after the small bit of blowback from the presta release I should be right there. :-)

I'm jumping around pumps. Got a cheap Nishiki at Dick's and it was near-impossible to pump past 90 p.s.i. Returned it and picked up a Topeak Joe Blows from Performance. Haven't tried it yet. Anyone have good lower-end pump recommendations?

Topeak is hard to beat in the way of quality:dollar. I've often used Topeak Joe Blow pumps as shop pumps, and have found that if no customers get to muck with them, I go through 2-3 in a season, and that's not even the whole pump, it's the seals and such, which Topeak actually offer in a rebuild kit. For home use, that Joe Blow should last you a long time, providing no one you know jams the Presta head on a Schrader valve or similar. The not-absolute-bottom-of-the-barrel Blackburn stuff is where I'd go if I wanted cheaper.

Other other thing - floor pump pressure gauges aren't super accurate. I forget where I read it originally, but +-5psi is apparently pretty common. I know for a fact going between pumps, you're definitely not hitting the same pressure regardless of the fact that gauges A and B give the same reading. It's way more important to find "your" ideal pressure with a given pump with a given tire on a given bike than it is to obsess over a couple-few psi. As said before, base it on ride feel more than anything else. Unless you're a pro racer, in which case your sponsor pays a mechanic to set your requested pressure with an accurate, stand-alone gauge, and then the numbers really do matter down to a fine point.

Much obliged.

Speaking of pumps, I recently ran into an interesting issue with the compact pump I carry to fix flats out on a ride.

It's got a mouse-tail design that screws onto a Presta valve (similiar to this), and several times, i found that when unscrewing the pump from the valve, what I was actually doing was unscrewing the valve head from the valve stem, thus blasting all that air that I'd just put into the tire back out again.

I've since taken to manually tightening the valve head on a new tube when I take it out of the box, and haven't had any recurrences of that problem.

Jonman, do you mean the valve core when you say "valve head"? Like the whole center bit of the valve is unthreading from the valve stem? If that's the case, that pump's air chuck must be getting a damned tight seal on things, or your valve cores are somehow loose to begin with. There are typically little flats on removable presta valve cores, which are made to fit a valve core removal tool, but they're usually just tight enough where you can budge them with pliers or a very small adjustable wrench. I like checking these, because if one's loose enough, it can theoretically loosen further from vibration and you can suddenly lose a lot of pressure unexpectedly, resulting in anything from a pinch flat to a crash when turning.

ianunderhill wrote:

Jonman, do you mean the valve core when you say "valve head"? Like the whole center bit of the valve is unthreading from the valve stem? If that's the case, that pump's air chuck must be getting a damned tight seal on things, or your valve cores are somehow loose to begin with. There are typically little flats on removable presta valve cores, which are made to fit a valve core removal tool, but they're usually just tight enough where you can budge them with pliers or a very small adjustable wrench. I like checking these, because if one's loose enough, it can theoretically loosen further from vibration and you can suddenly lose a lot of pressure unexpectedly, resulting in anything from a pinch flat to a crash when turning.

Yeah, that's exactly what I meant. Terminology fail!

The pump does get a damn tight seal, although to be fair, it didn't require a lot of torque to start it moving, either the valve core in the case of it going wrong, of the pump's chuck in the case of it going right.

I think the problem is largely that the tubes I buy (Q-tubes) tend to be delivered with the valve core not snugged into the stem all that tight. I use a small adjustable wrench to torque them up, and that's solved my problem.

Not all tubes have removable cores, though-- you could just get regular Presta tubes instead :D. QBP's tubes (Q-Tubes) are labelled as such (removable versus non), so make sure to double-check the box before leaving the shop.

Once, a local shop (not ian's) had accidentally stocked only removable-core tubes, and my pump's screw-on chuck was constantly unscrewing the valve cores. After the 3rd attempt at a return, I finally sat with the mechanic and went through their tubes one by one to make sure they had some regular-core tubes (some regular boxes were also mislabeled).

WipEout wrote:

Not all tubes have removable cores, though-- you could just get regular Presta tubes instead :D. QBP's tubes (Q-Tubes) are labelled as such (removable versus non), so make sure to double-check the box before leaving the shop.

Once, a local shop (not ian's) had accidentally stocked only removable-core tubes, and my pump's screw-on chuck was constantly unscrewing the valve cores. After the 3rd attempt at a return, I finally sat with the mechanic and went through their tubes one by one to make sure they had some regular-core tubes (some regular boxes were also mislabeled).

Well I never! It's quite possible that numpty me just happens to always pick up the removable core ones. Or that the tri shop has a limited selection of 650 tubes and they're all removable core. I'll look more closely - thanks for the tip-off.

What's the point of the removable core anyway?

The point of the removable core is that you can replace it if you damage the valve core (bend the pin, break part of it off, etc.). Very handy if you damage the valve core in your tubular tires, in which case you'd otherwise be effed, do the same to the valve cores of your expensive latex tubes, you don't want to replace your whole tube just because you mangled the valve core, and so on. A tri shop is even more likely to stock tubes with removable valve cores, as some valve extenders designed for use with deep aero wheels are designed with their own integrated valve cores, and thus fit into the valve stem as a replacement valve core, rather than on top of the existing valve stem and valve core. The other thing is that, as 650C tubes have become less popular, shops in general are likely to only bother stock multiple stem lengths in the size and leave it at that.

I will say my own shop primarily stocks tubes with removable valve cores, with the occasional exception of some non-QTubes stuff. But then we're a tri shop and we have more situations that warrant it than not, so it's easier to mainly carry those over the non-removable. I don't see the loose valve core thing happen much, but I tend to double check anything I install for a customer. I wouldn't call it common, but it is possible. WipEout's owning and use of a Lezyne pump is a highly likely a partial culprit - they're very well-built and tend to get a pretty tight seal in my experience.

The More I Know!

Cross-posting this here from the video thread because... well, damn, watch it, that's why!

Katy wrote:

Crazy bike riding (via Edwin)