dan,
i'm very interested in what you said about a high cadence. riding a high cadence in a triathlon will help you have an easier run transition. so if one was NOT worried about aerodynamics but just having a better run experience...buying a tri geometry bike would not make a significant difference....it's more about the way you ride and developing your body to be able to jump from bike to run without too much physical shock......

¥ as a rookie i'm interested in good fundamental practices...NOT the minutia(sp) of theory, although it is interesting

¥ unless things change i don't see any significant advantage riding a tri geometry bike over a road bike in order to have a better run....i was wondering if a lot of people would say, "you have to get a tri geometry bike because it really alleviates a lot of the struggle when getting off of the bike and running...but i don't see that...it's about training...."


¥ buy a tri bike for aerodynamics not because it helps you on the run UNLESS higher cadence is easier on a tri geometry bike....


¥what about the SLAM position....??????? you get aerodynamics too but on a road bike???

I don't think the direction and force of gravity play a significant factor at all as it relates to the movement of the feet around the BB. It isn't like your feet are moving in smaller circles if you rotate forward (the range of motion is the same and the muscles must execute this range independent of the direction of gravity). Earth's gravity is so weak compared to the forces exerted on/by the bike and body.

Even if you take it to an extreme where the femur doesn't have to move 'up and down' at all I don't see there being a significant impact caused by the force of gravity.

OT

The upward force transmitted to the legs is opposed by your body's weight (its anchored in your seat). It takes a huge amount of force to budge even the smallest hiny - even in an unweighted aero position. ;)

That is a concern for someone riding EXTREMELY steep or shallow but not for the range of positions normally addressed in these discussions.

OT

I'm not talking about 'unweighting' the saddle. This is difficult without the ability to draw, so I'm going to do something real goofy...

Remember in jr high science class learning about levers. Check the attached link and scroll down to Type 2 or Second Class levers

http://www.enchantedlearning.com/...achines/Levers.shtml

Imagine your saddle as the fulcrum, the 'load' as your body's center of mass or gravity which lies ahead of the saddle (fulcrum), and your body as the 'lever'. The strength of your hip extension gives the lever 'rigidity'. "Effort" (using the simplified terminology of the link) is provided by your legs and arms. Effort supports the load.

If you think of your body pedaling a bike as a type 2 lever, it would seem that the only thing that changes as you rotate your body around the bottom bracket while keeping the spacial relationships of your contact points with the bike the same, is the directional 'load' of your body in relation to the pedals.

With steep geometry, the fulcrum (saddle) is moved horizontally closer to one of the two points that provide 'effort' (i.e. the pedals/bottom bracket). Slack geometry, the saddle is farther behind the bottom bracket and allows the 'effort' of pedaling forces to provide a greater contribution in supporting your body weight as long as the hip extension of your pedal stroke remains strong. Pedal hard enough with slack geometry and you can keep very little weight on your hand/arms. The hip extension contributing to turning the pedals is supporting your upper body. Steep geometry with the saddle almost over your bottom bracket, you have to support your upper body with your arms. Steep geometry requires a less forceful hip extension as hip extension is not being used to contribute to the supporting the 'load' of the riders body centered ahead of the saddle.

Don't know if I'm making any sense or not, but it's the best I can do. I'm also not sure if the difference is significant. It's simply the only effect I can see gravity could possibly have on the whole steep/slack issue when keeping body position constant.

SocalRookie,

I was wondering about the exact same question a while ago. After reading quite a bit of the web (here and on other sites) I decided that there was no absolute answer. I decided that I would find out for myself by buying a tri bike and giving it a fair try. If I found significant improvement on my running (or biking, let's have an open mind) then I would keep it, if not then I would resale it and would be in for a few hundred bucks, which would be an acceptable price for me to pay for answering that same question. However life got in the way and I still haven't acquired that tri bike, but I will as soon as I can. Hope that helps...

For me the answer is "NO" I was actually about 15 seconds slower in the first mile of races in which I used my Tri bike. It most likely had more to do with redlining the heart rate than the different position. I have read 100 times that it is all about the fit on this forum...and I believe it applies to your question. I seem to have to get my HR higher on the tri bike to do the comp speed as my road bike.

I've been wondering the same thing.....I ride a Cannondale road bike - road geometry - fitted by Steve Larsen. I'm a lot slower on the bike now than 12 years ago in college (rode like 2:35 at Wildflower half in college but not paced well and died on the run - never fitted - road geometry at that time....). I digress - Now I still ride like 5-6 cm behind BB - I ride 95-105 cadence for 3 hours no problem. I have no strength - can't push many watts at all - current half IM bike time is like 2:50 but am running off the bike well (like 1:40 half marathon in half IM - which is good for me). I run off the bike almost as well as I can run stand-alone. Why? I run more now? - I spin higher cadence? So if I can already spin would a steeper bike help me? I have long legs - ? femur vs. tibia length. I'm toying with the idea of asking Ves to make me a Yaqui - likely 76 or 78 degrees - will it help? Would I be more comfortable? More aero? I'm not all that flexible but my position is o.k. Would I run faster? Would it help (again)? No idea. But I'm sick of not knowing and figure there's only one way to find out.....I've read a ton and there's no definite consensus. This site is definitely steep-oriented. I doubt it really matters (engine and all - individual variablity....) but will likely spend 3K to find out cuz who knows.....

Once again - can anybody tell me about leg length and femur vs. tibia length and theories re: fit.....I've searched and searched......slowman?

Dave, I've asked this question in the past also with no response. Specifically, what constitutes have a "long" tibia relative to the femur. Is it supposed to be a 1:1 ratio for upper and lower? Does my femur have to be longer than my tibia for me to be considered one with a "long femur"? I know it sounds so basic, however, I have not found conclusive evidence one way or another.

it seems to me that any of you could answer this question really easily...just do an actual test!!!just ride your favorit route and then run on both types of bikes.....i'd completely accept and more importantly understand your general expereice rather than a bunch of mathmatical mumbo jumbo....if it takes an understanding of physics to appreciate the subtlties between running off of a tri bike rather than a road bike...well than there is no difference to me....we all know are bodies really well and can tell ourselves exactly how we feel during the run or bike and swim....i trust that.....

i have to say i'm actually shocked that a tri gemometry bike makes that little difference considering how much ink they get in here....unless you are gunning to place....there dosen't seem to be a huge reason to enjoy a tri bike over a road bike....and all the aero talk might not even matter if you can ride in a SLAM position......right????????....either way you sell it there is no significant improvement into the run phase from a tri bike or road bike......

Quote from OzTriGuy “You will race best on what you prepare on.”



While I would normally agree with this, I think this is only the case if what you prepared on is set up correctly. I prepared on my race bike early this year, but started the season with two horrible rides until I figured out my hip angle was too acute. I then bought a seat shifter and put it on THREE days before I raced the Blackwater Eagleman Half-IM. The bike course is pancake flat and you ride aero the whole time. It felt right and I had my best bike split ever with none of the discomfort I had in previous races.

When I am in the aero position my point of contact with the seat is very nearly directly over the bottom bracket. The best way I can describe the feeling is that I am “suspended” over the pedals. I like DevashishPaul’s description of why it is easier for me to pedal at high rpm.

Ten years ago I raced in France and rode the great Alpine passes on a very shallow bike with the seat as far back as it would go. This was a great way to power up some of the absurdly steep climbs. However, I found that I could only do this for a limited amount of time before I was toast. Slowman would describe this as recruiting too much fast twitch fiber and I think he was right. As long as the pass wasn’t too steep, I could spin away forever (some passes were as long as 30KM).

Alpe D’Huez on the other hand, or the north face of the Galibier, was too steep to spin my 38x24 and pretty soon I couldn’t turn the pedals.

Fast forward ten years to this past summer. I raced at the Armed Forces Triathlon championships in June on my tri bike and then drove back across the country on a vacation with my family. On the way we passed Mt. Evans in Colorado, the highest paved road in the U.S. at 14,200+ feet. I rode it as a kid and figured I’d try again. I was a little concerned that it would be hard on a steep angled bike, but I found that I could sit and spin in my 38x21 and had no problems getting to the top (except that the air is very thin above 10,000 feet).

I think this was a result of pedaling more “circles” rather than mashing the downstroke. If you don’t have to run afterwards, it might not matter, but if you do I think it makes a big difference. Once you start digging into your "power" (I think the explanation that too hard an effort recruits fast twitch fibers is the best I have ever heard), then you are draining the tank and it will empty very quickly.

After two months of limited work on PowerCranks this fall, I raced my last tri of the year on regular cranks and was amazed at how my pedal stroke felt. It was especially notable on the hills. The result was that I rode and ran faster than the year before on less training volume.

I think the one disadvantage of the slam is that you cannot get very low in front and have to be extremely flexible to ride with a flat back. It will also put more weight on your seat vs. the forearms and I think that makes it harder to relax and pedal circles.

I arrived at my very steep position strictly by experimentation with what felt good while riding on the aerobars and striving for a flat back. This site would have helped me get there sooner, but I think the forward position is the only way to go and this from a former bike racer of many years.

I've watched and followed many ITU style races, both tri & du, and have not seen much decline in run times from the Pros compared to non drafting races where the Pros use "Tri" bikes. Yes, I know many times they are drafting and "conserving energy". For those of us who have witnessed these events, they are still busting their butts on the bike, just going a little faster. Many times they go on break a ways and still run comparable 10k times off the bike. Just curious as to whether anyone as looked at it from this angle or had any thoughts - Thanks

as I understand it, there are two good reasons to use a tri (steep angle) bike:
1. more comfort in aero position = more time spent in aero position = faster
2. the documented (both the study cited, and anecdotal evidence) speedup in the run afterwards

That said, my personal data point: I ride a road bike with aero bars, Olympic and sprint only. After many years I've tweaked the position and trained my 'run-after-bike' legs to the point where I run only 30sec to a minute slower on the run leg than in standalone 5k and 10k races. I find it hard to believe a steep-angled bike would allow me to run any faster than that. If I was doing long distance races this might well be different: also I'd seriously consider the tri bike even if it was just for the aero advantage.

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"It is a good feeling for old men who have begun to fear failure, any sort of failure, to set a schedule for exercise and stick to it. If an aging man can run a distance of three miles, for instance, he knows that whatever his other failures may be, he is not completely wasted away." Romain Gary, SI interview

In another string yesterday I expressed the opinion that illegal drafting that goes on at a lot of races might not be all that effective at increasing one’s time. I believe it because most of the “pacelines” are not that tight and the “pulls” require you to surge all the time.

ITU draft-legal racing is another story. These athletes ride in packs and pacelines just like in a bike race and they are much better organized. A bunch of world-class athletes riding together at their top end should be riding 40K in 50 minutes or less every time. Combine that with a 17-18 minute swim and a 31-32 min run plus transition and these guys should be finishing in an hour 40 minutes or less. Since I have never seen a time that fast it leads me to believe that they don’t ride as hard as they could.

Why would Simon Whitfield hammer on the bike when he can run so fast? For that matter, applications for the US Olympic resident team don’t even require you to show any cycling performance. Why? Because the ITU-style of racing makes the bike irrelevant as long as you are good enough to swim and then hang out in the peloton.

Don’t get me wrong, I’m sure these guys still ride hard, but I don’t think you can compare drafting and non-drafting performances when running off the bike.Also, we don’t know that they ride at different seat angles just because they have drop bars on the bike. They could still ride 78 degree seat angles but without the really low front end.

The answer to the original question is Yes, I do run faster off my tri bike than a road bike. The reason I know this is I went from a tri bike to a road bike. For the two seasons on the road bike my volume in both the cycling and running were higher BUT my times were a mere 1.5-3 min slower on the bike and another 2 or so min on the run. I went from 58-9 min 40k with 36 min runs to 62-4 min bikes and 38-9 min runs. I bought a tri bike and 10 days later rode a high 57 and ran a low 36.
So the answer to this thread, for myself anyway, is go steep to go fast.

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Brian Stover USAT LII
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