TT Bike or Road bike - uphill 5 mile TT @ 5% gradient

Aug 28, 14 13:24

Post #1 of 36 (5334 views)

As title says its 5 miles @ average of 5.3% (very steady gradient, max is 7%, min 4% so not much variation at all)

I am 89KGs, 6' 3", ftp of 305Watts, wide shoulders.

From non scientific observation I can put out almost as much power in TT position as on Road Bike. (probably circa 10 watts less at threshold)

I reckon I'll be going between about 11-13mph average.

So would I be faster on TT bike or Road Bike (I could also put clip ons on road bike).

I would assume at those speeds aero stuff offers diminishing returns, (so no disc wheel I guess, aero helmet though?, skinsuit ?)

Say the wind was largely tail on the day, are you better off again on a road bike sat up, with the wind having more 'area' to push you up.

Last edited by: big_vern: Aug 28, 14 13:24

Re: TT Bike or aero Road bike - uphill 5 mile TT @ 5% gradient [big_vern] [ In reply to ]

Aug 28, 14 13:26

Post #2 of 36 (5322 views)

you can use this page on analytic cycling to work this out for yourself, if you have a reasonable guess of your CdA on each bike:

http://analyticcycling.com/...LessWeight_Page.html

5% at your w/kg will tend towards the TT bike being a teeny bit faster if you make the same power on it. Depending on mass difference and such.

If you make 10 less watts, maybe not. run the numbers!

Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [big_vern] [ In reply to ]

Aug 28, 14 13:26

Post #3 of 36 (5322 views)

How much lighter is the road setup? Which one do you practice climbing form in more often?

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Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [umcade] [ In reply to ]

Aug 28, 14 13:32

Post #4 of 36 (5301 views)

I climb very little on either tbh, flat round here (road bike is a bianchi oltre xr2 which when I got it I was told is just under the UCI limit, TT bike is a heavier Argon18 E114, I would guesstimate the TT bike to be 1.5KGs heavier)

I am flexible with a strong core so can hold the TT position fairly well for long periods.

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [big_vern] [ In reply to ]

Aug 28, 14 13:52

Post #5 of 36 (5259 views)

If it were me, I'd use a road bike with aero wheels, a tight fitting skinsuit and a TT helmet.

Re: TT Bike or aero Road bike - uphill 5 mile TT @ 5% gradient [jackmott] [ In reply to ]

Aug 28, 14 13:53

Post #6 of 36 (5253 views)

ta for link, well it looks fairly close if I take off 10 watts for the TT bike and the extra weight,,

there is normally a tail wind on the course so I'd lean towards the road bike..

Re: TT Bike or aero Road bike - uphill 5 mile TT @ 5% gradient [big_vern] [ In reply to ]

Aug 28, 14 14:07

Post #7 of 36 (5224 views)

Road bike with skinsuit, aero helmet, shoe covers, etc.

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [big_vern] [ In reply to ]

Aug 28, 14 14:25

Post #8 of 36 (5183 views)

Sounds similar to Lookout Mtn here in Denver/Golden. Pretty sure I personally would go with my road bike on that over my tri bike.

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Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [big_vern] [ In reply to ]

Aug 28, 14 19:38

Post #9 of 36 (5009 views)

We have a very similar TT in our local stage race, but with a short downhill and a flat section at the end. Folks used to ride road bikes with clip-ons, but they got tired of the TT bikes beating them. At 12-13 mph there is still a substantial aero advantage to be had on the TT bike, if you can generate nearly the same power as on the road bike.

I ride it regularly on both road and TT bike in training, so I have a lot of data. The TT bike is 30-40 seconds faster on the hill alone, even more for the full course.

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [eb] [ In reply to ]

Aug 28, 14 19:46

Post #10 of 36 (4998 views)

This if you can stay tucked and can still put out same power at ~12-14 mph. See US Pro Tour Challenge uphill section and Teejay or Uran at moderate hilly 1st TT of the Giro. A lot of riders though have power disparities on road versus tt (could be 20 watt difference from the data I've seen lately from the Pro Ranks). If that is the case back to the roadie.

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Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [eb] [ In reply to ]

Aug 28, 14 19:48

Post #11 of 36 (4995 views)

eb wrote:

We have a very similar TT in our local stage race, but with a short downhill and a flat section at the end. Folks used to ride road bikes with clip-ons, but they got tired of the TT bikes beating them. At 12-13 mph there is still a substantial aero advantage to be had on the TT bike, if you can generate nearly the same power as on the road bike.

I ride it regularly on both road and TT bike in training, so I have a lot of data. The TT bike is 30-40 seconds faster on the hill alone, even more for the full course.

Something seems off....30-40" is what most claims are for a TT bike in a 40k TT vs. a road bike. Seems like a HUGE delta for a 5 mile, uphill TT.

Chicago Cubs - 2016 WORLD SERIES Champions!!!!

"If ever the time should come, when vain and aspiring men shall possess the highest seats in government, our country will stand in need of its experienced patriots to prevent its ruin." - Samuel Adams

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Power13] [ In reply to ]

Aug 28, 14 20:32

Post #12 of 36 (4964 views)

Power13 wrote:

eb wrote:

We have a very similar TT in our local stage race, but with a short downhill and a flat section at the end. Folks used to ride road bikes with clip-ons, but they got tired of the TT bikes beating them. At 12-13 mph there is still a substantial aero advantage to be had on the TT bike, if you can generate nearly the same power as on the road bike.

I ride it regularly on both road and TT bike in training, so I have a lot of data. The TT bike is 30-40 seconds faster on the hill alone, even more for the full course.

Something seems off....30-40" is what most claims are for a TT bike in a 40k TT vs. a road bike. Seems like a HUGE delta for a 5 mile, uphill TT.

40 seconds over 40k would only be a 10W difference (ROT IS 10W ~= 1s/km) in aero drag between the road and TT setups. That seems fairly low to me.

http://bikeblather.blogspot.com/

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [big_vern] [ In reply to ]

Aug 28, 14 20:55

Post #13 of 36 (4938 views)

I raced San Dimas Stage RAce TT and Joe Martin Stage Race TT this year on the pro NRC circuit. Both uphill at about 5-6% average and 95+% of riders were on road bikes with maybe only 20% using clip ons. And this with average speeds approaching 28-30kmh.

For the vast majority of pros it would seem uphill absolute power is compromised on a TT rig. So unless you know you can crank the torque and watts in aero I would stick to the roadie, especially considering your speed will be 8-10kmh slower.

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Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Power13] [ In reply to ]

Aug 29, 14 2:41

Post #14 of 36 (4841 views)

Power13 wrote:

eb wrote:

We have a very similar TT in our local stage race, but with a short downhill and a flat section at the end. Folks used to ride road bikes with clip-ons, but they got tired of the TT bikes beating them. At 12-13 mph there is still a substantial aero advantage to be had on the TT bike, if you can generate nearly the same power as on the road bike.

I ride it regularly on both road and TT bike in training, so I have a lot of data. The TT bike is 30-40 seconds faster on the hill alone, even more for the full course.

Something seems off....30-40" is what most claims are for a TT bike in a 40k TT vs. a road bike. Seems like a HUGE delta for a 5 mile, uphill TT.

Really? A TT bike is only worth 3/4 to 1 sec/km over a road bike? Not on this planet, where just putting clip-ons on a road bike saves 1-1.5 sec/km.

But thanks for making me re-examine my numbers. I'll grant you that my delta(road-TT) is probably larger than most. My TT position has pretty low drag (CdA .21-.22), but my road bike position is fairly upright. Also, the wheels that live on my TT bike are much more aero than the training wheels on my road bike, and have lower Crr.

That said, I'll still stand by the statements made above, particularly the underlined one. If you don't believe it, just go to analyticcycling and plug in the numbers. It's just physics!

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [big_vern] [ In reply to ]

Aug 29, 14 3:22

Post #15 of 36 (4818 views)

TT bike. And disc. Always disc.

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Jordano] [ In reply to ]

Aug 29, 14 5:23

Post #16 of 36 (4753 views)

Joe Martin is 6.8% average according to one source I checked, and while almost everyone uses a road bike, it has been won on a TT bike before on the men's side!

I rode the course a few times this year and was thinking hell yes I would use a TT bike, if I had a light one...but I'm weird in that I lose no power.

Jordano wrote:

I raced San Dimas Stage RAce TT and Joe Martin Stage Race TT this year on the pro NRC circuit. Both uphill at about 5-6% average and 95+% of riders were on road bikes with maybe only 20% using clip ons. And this with average speeds approaching 28-30kmh.

For the vast majority of pros it would seem uphill absolute power is compromised on a TT rig. So unless you know you can crank the torque and watts in aero I would stick to the roadie, especially considering your speed will be 8-10kmh slower.

Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Tom A.] [ In reply to ]

Aug 29, 14 7:40

Post #17 of 36 (4645 views)

Tom A. wrote:

Power13 wrote:

eb wrote:

We have a very similar TT in our local stage race, but with a short downhill and a flat section at the end. Folks used to ride road bikes with clip-ons, but they got tired of the TT bikes beating them. At 12-13 mph there is still a substantial aero advantage to be had on the TT bike, if you can generate nearly the same power as on the road bike.

I ride it regularly on both road and TT bike in training, so I have a lot of data. The TT bike is 30-40 seconds faster on the hill alone, even more for the full course.

Something seems off....30-40" is what most claims are for a TT bike in a 40k TT vs. a road bike. Seems like a HUGE delta for a 5 mile, uphill TT.

40 seconds over 40k would only be a 10W difference (ROT IS 10W ~= 1s/km) in aero drag between the road and TT setups. That seems fairly low to me.

Sorry....poor phrasing on my part. I was referring mostly to the frame, not the resulting change in position, as well. And with the speeds the OP was talking about (12-13 mph), I doubt many people are holding an aero position.

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"If ever the time should come, when vain and aspiring men shall possess the highest seats in government, our country will stand in need of its experienced patriots to prevent its ruin." - Samuel Adams

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Power13] [ In reply to ]

Aug 29, 14 7:51

Post #18 of 36 (4636 views)

Power13 wrote:

Tom A. wrote:

Power13 wrote:

eb wrote:

We have a very similar TT in our local stage race, but with a short downhill and a flat section at the end. Folks used to ride road bikes with clip-ons, but they got tired of the TT bikes beating them. At 12-13 mph there is still a substantial aero advantage to be had on the TT bike, if you can generate nearly the same power as on the road bike.

I ride it regularly on both road and TT bike in training, so I have a lot of data. The TT bike is 30-40 seconds faster on the hill alone, even more for the full course.

Something seems off....30-40" is what most claims are for a TT bike in a 40k TT vs. a road bike. Seems like a HUGE delta for a 5 mile, uphill TT.

40 seconds over 40k would only be a 10W difference (ROT IS 10W ~= 1s/km) in aero drag between the road and TT setups. That seems fairly low to me.

Sorry....poor phrasing on my part. I was referring mostly to the frame, not the resulting change in position, as well. And with the speeds the OP was talking about (12-13 mph), I doubt many people are holding an aero position.

Then something is wrong about their aero position...I can hold mine going up am 8% average grade! going ~9mph or so, ~20 minutes at a time...

Even so, depending on the road and TT frames being considered, it most likely is well more than 10W on the frame alone...heck, I saw more like 10-15W just between a P2K and a P3C.

http://bikeblather.blogspot.com/

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Tom A.] [ In reply to ]

Aug 29, 14 8:01

Post #19 of 36 (4621 views)

So because you can hold your position like that, everyone should / can?

What ever happened to "N=1"?

The reality is that at speeds higher than even the 12-13 mph noted by the OP, people start bailing out of their aero position. What was Rapp's "breaking point" where the data indicated he was better sitting up? IIRC, it was around 15 mph, and he obviously has a very slippery position.

Chicago Cubs - 2016 WORLD SERIES Champions!!!!

"If ever the time should come, when vain and aspiring men shall possess the highest seats in government, our country will stand in need of its experienced patriots to prevent its ruin." - Samuel Adams

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Power13] [ In reply to ]

Aug 29, 14 8:32

Post #20 of 36 (4595 views)

Power13 wrote:

So because you can hold your position like that, everyone should / can?

What ever happened to "N=1"?

The reality is that at speeds higher than even the 12-13 mph noted by the OP, people start bailing out of their aero position. What was Rapp's "breaking point" where the data indicated he was better sitting up? IIRC, it was around 15 mph, and he obviously has a very slippery position.

Jordan has a slippery position for a long course triathlete, I'm pretty sure he could get slipperier if he was concentrating on short TTs ;-)

In any case, you're getting off the point that the difference between a typical road frame of today and a TT frame is usually more than ~10W.

http://bikeblather.blogspot.com/

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Tom A.] [ In reply to ]

Aug 29, 14 8:49

Post #21 of 36 (4568 views)

Actually, my point was that it seemed unlikely that a TT frame on a 5 mile, 5% grade TT would yield a 40" difference. Wink

Wink

By your own math, a 10w difference would only yield a 8" difference for a 5 mile TT. So in order to save 40", you would need a frame that saves you 50w.

Correct me if I am wrong, but the time savings of 10w = 1 sec / KM saved is also based on a 30 mph test (or maybe 40 kph?) The speeds for this uphill TT would be substantially less, correct? So doesn't your time saved / KM also drop?

Chicago Cubs - 2016 WORLD SERIES Champions!!!!

"If ever the time should come, when vain and aspiring men shall possess the highest seats in government, our country will stand in need of its experienced patriots to prevent its ruin." - Samuel Adams

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Power13] [ In reply to ]

Aug 29, 14 9:02

Post #22 of 36 (4552 views)

Power13 wrote:

Actually, my point was that it seemed unlikely that a TT frame on a 5 mile, 5% grade TT would yield a 40" difference. Wink

Wink

By your own math, a 10w difference would only yield a 8" difference for a 5 mile TT. So in order to save 40", you would need a frame that saves you 50w.

Correct me if I am wrong, but the time savings of 10w = 1 sec / KM saved is also based on a 30 mph test (or maybe 40 kph?) The speeds for this uphill TT would be substantially less, correct? So doesn't your time saved / KM also drop?

Well...that's where we start getting into the true differences between people's positions on road bikes and TT bikes...heck, I've seen my drag on my TT bike go up by the equivalent of ~20W just if my bar height is too high by 5mm.

The ROT is based on typical TT speeds, so yeah, it would be de-rated for this sort of TT...which just goes to show the best thing to do for these decisions is to model the whole thing up. It's not that hard ;-)

http://bikeblather.blogspot.com/

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Power13] [ In reply to ]

Aug 29, 14 10:57

Post #23 of 36 (4478 views)

Power13 wrote:

Actually, my point was that it seemed unlikely that a TT frame on a 5 mile, 5% grade TT would yield a 40" difference. Wink

Wink

That does seem unlikely. But nobody has made that claim, have they? The discussion is about TT bikes, not TT frames, no?

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [Power13] [ In reply to ]

Aug 29, 14 11:05

Post #24 of 36 (4468 views)

Power13 wrote:

And with the speeds the OP was talking about (12-13 mph), I doubt many people are holding an aero position.

Anyone riding a TT who isn't holding an aero position at 12-13 mph is giving away time to the competition. In a short TT, the only reason to be out of aero position at those speeds is if you are one of those folks who can't generate power in the TT position. In a longer TT, 12-13 mph may be your opportunity to stretch and relax a bit - but you're still giving up time.

Re: TT Bike or Road bike - uphill 5 mile TT @ 5% gradient [eb] [ In reply to ]

Aug 29, 14 11:11

Post #25 of 36 (4461 views)

Thanks guys

Eb - ""My TT position has pretty low drag (CdA .21-.22), but my road bike position is fairly upright""

That's me as well (not saying anywhere near your CdA, just in comparison to road bike posistion) , I have a pretty good TT posisition I can hold, but roadbike is fairly upright, that's why I mentioned in orginal post that there is, more often than not, a decent tail wind.

On my road bike I would benefit more from that tailwind as will be presenting more surface area to get blown up the hill?

Ok - so I know with my weight I'm gonna be well towards the back of the field and much much slower than the top guys but was genuinely interested in getting the best performance for myself so thanks for all the replies.

Last edited by: big_vern: Aug 29, 14 11:12

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