Hey guys,
I’m doing Race Across America this summer.
My TT bike will be the P5-X.
Does anyone one if the bike is fastest with or without the down tube storage box which can be removed.
Since I have support cars I dont need the box for storage on this one but would leave it on if it improves aerodynamic drag.
Seem to recall that the Trek Speed Concept was faster with the rear storage on. Thought maybe the same could be the case here.
Good Sunday all around.
Kind regards
Michael
IIRC, there is no difference between the two set-ups. They had some info out on the interwebs about this at some point.
No difference.
However if you add a bottle cage then you lose 1 watt.
Think this is regardless of setup with or without the storage box.
Speedcase fitted — net aero: 0g drag
Horizontal bottle in place — net aero: +23g drag
Diagonal down tube bottle in place — net aero: +29g drag
Bottle between extensions — net aero: +41g drag
Rear bottle mounted — net aero: +5g drag
Base bar up position — net aero: -15g drag
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Thanks for the reply.
I actually thought horizontal bottle between aero extensions was close to aero neutral 🤷ðŸ»â€â™‚ï¸ðŸ™ˆ
Luckily the base bar is flipped up hehe
do you have the source for that?
do you have the source for that?
https://www.bikeradar.com/features/cervelo-details-its-reasoning-behind-the-p5x-design/
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Speedcase fitted — net aero: 0g drag
Horizontal bottle in place — net aero: +23g drag
Diagonal down tube bottle in place — net aero: +29g drag
Bottle between extensions — net aero: +41g drag
Rear bottle mounted — net aero: +5g drag
Base bar up position — net aero: -15g drag
So according to this you are better to forgo the BTA and run the speedcase with the bottle mount on it? That seems to run counter to all the pro’s and pictures of setups I have seen.
Anyways thanks for the read, this is helpful
Speedcase fitted — net aero: 0g drag
Horizontal bottle in place — net aero: +23g drag
Diagonal down tube bottle in place — net aero: +29g drag
Bottle between extensions — net aero: +41g drag
Rear bottle mounted — net aero: +5g drag
Base bar up position — net aero: -15g drag
So according to this you are better to forgo the BTA and run the speedcase with the bottle mount on it? That seems to run counter to all the pro’s and pictures of setups I have seen.
Anyways thanks for the read, this is helpful
I think the reference to the BTA must be largely with a wide arm position and bottle in the way or above the arms.
Realistically, aero has progressed and most of us have the BTA hidden between elevated arms now so I too don’t agree with that comment.
Thats what I assume to be the case as well. I would also think that running the BTA is better overall considering reaching down to drink would impact your aero more than drinking from a BTA.
Also I thought the down tube bottle position was aero neutral. IMO +/-1~2 watts is pretty meaningless in terms of overall impact (considering manufacturer errors on power meters) but its again good data to digest. I still think I will run the BTA without the speedbox and all bottle positions accessible, with the integrated mod Yan designed. Will likely do BTA, integrated system and BTS positions loaded up first with the downtube loaded last if needed for IM racing. I am just playing with running a torpedo vs doing a bottle in the BTA.
Thats what I assume to be the case as well. I would also think that running the BTA is better overall considering reaching down to drink would impact your aero more than drinking from a BTA.
Also I thought the down tube bottle position was aero neutral. IMO +/-1~2 watts is pretty meaningless in terms of overall impact (considering manufacturer errors on power meters) but its again good data to digest. I still think I will run the BTA without the speedbox and all bottle positions accessible, with the integrated mod Yan designed. Will likely do BTA, integrated system and BTS positions loaded up first with the downtube loaded last if needed for IM racing. I am just playing with running a torpedo vs doing a bottle in the BTA.
Speaking from experience, the torpedo is very functional just a pain with sticky cockpit refills. Got sick of it.
I now race 70.3 with bladder, aerobottle on downtube and behind saddle refill. Does for most or else replace 1 bottle if needed.
For ironman, I’m debating whether to switch aero downtube for standard bottle.
Losing the 1w drag vs the convenience of bigger bottle and easier for aid stations will probably work best.
May bin the behind saddle option instead.
Don’t use BTA anymore. The fuelselage has freed up that and enabled a narrower arm position for more aero gain.
So for me, it will be fuelselage and 1 x downtube/top of speedcase bottle for IM.
Replace and refill as needed at aid stations.
Do you notice any difference in handling or feel, when not using BTA? Can’t recall when last ridden a TT bike without BTA, but I’m guessing there migth be some upside here.
Do you notice any difference in handling or feel, when not using BTA? Can’t recall when last ridden a TT bike without BTA, but I’m guessing there migth be some upside here.
A small bit for sure better without BTA.
But most tri courses are negligible for handling requirements so not a big deal unless doing lanza maybe.