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Giant P-SLR 1 Aero VS Deep Dish Tubular

Posted on June 25, 2012 by Big

So I performed my DIY wheel test this morning in fairly windy but dry conditions. I decided not to go the full distance to Mordi & back as this would have made me late for work and run the risk of being delayed by traffic etc. In the end I did 2 tests, riding from Black Rock to Parkdale & back, covering a little over 14klms each trip. Here are the results:

Wheels	Distance	Ave Cad	Ave Power	Ave HR	Max HR	Ave Speed	Time
Bouwmeester	14.04k	89	307	126	138	38.15	22:05
Giant P-SLR1	14.03k	87	307	128	153	38.76	21:43

My start times were about 30 mins apart & I have since checked the BOM site and the difference in the winds at both times were negligible. My second run was shorter by 10 meters, not much but due to the turnaround point being a Beach Rd house rather than something fixed like a traffic island.

My sole focus was to ensure my wattage for each run was identical. 300 watts is about 75% of full race pace so was generally comfortable. I also found that, during the second run I had a better feel for my pace and was able to very closely replicate the output from my first ride.

Interestingly my first run felt faster but other than my max HR all other measures including cadence & HR were pretty much the same for both times.

This big news is that my second ride on my GIANT P-SLR1 AERO’s came up trumps, posting a time that was more than 20 seconds better than my Bouwmeester Deep Dish tubulars. I should note that I had both tyres pumped up close to the max recommended pressure.

I am not certain that my test is an exact science but there are no prizes for guessing what I will be racing on this weekend.

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5 Responses to Giant P-SLR 1 Aero VS Deep Dish Tubular

Craig says:

June 26, 2012 at 1:51 pm

Hey Big, good to see your wheel test.
I’m curious to know what tyres you ran on both sets of wheels(I’m assuming the Bou’s were tubbies and the giants clinchers). Reason being that unless you run similar tyres from the same company(ie Vittoria Corsa CX Tubs Vs Corsa CX open clinchers)your results could be out. Doing this will give you a better chance of evaluating the aerodynamics advantage of the wheels sets. Unless of course you just want to know which combination was faster.
I would have also thought that running your tyre pressures at the same psi would have been better too.
BTW your results don’t surprise me at all as clinchers have been shown years ago to provide lower rolling resistance then tubbies.
Didn’t Tony Martin win the world champs last year on clinchers too?
Cheers Craig
Big says:

June 26, 2012 at 4:21 pm

G’day Craig

Nup, I don’t care about what kind of tyres I am running – just want to know which set up is faster. I do have Corsa CX Tubs and Conti GP4000 clincher.

Yes the tyre pressures were different but I pumped both wheels up to the pressure that I would prior to any race.

My sole aim for this test was to guage which of my two race wheels, in their current confirguration were going to give me the best bang for my buck for this weekend’s TT.

My learned colleagues reckon I should do the test again, just to be sure, reversing the order. Stay tuned for next weeks installment. Might even borrow Daveoos disc to make things really interesting
tom crebbin says:

June 26, 2012 at 4:24 pm

HI John I find these tests very interesting and I noticed at the boulevard TT you had the SLR’s on your bike and you rode well.When I saw your initial story I got the feeling you were hoping the SLR’s would be faster. Anyway it looks like an interesting test and you have done your utmost to keep all things consistent in so far of watts outputt, distance,cadence and average heart rate. One interesting figure is max HR where the SLR ride peaked at 153 compared to 138 on the Bouwmeesters. If the 153 heartv rate was achieved at the very beginning it could mean that you got yourself up to speed quicker than the other ride an therefore had more time at the desired wattage.I find that in short TT tests it’s important to get to the desired speed as fast as you can. Taking a long time to get there affects your average. It could also be that a car pulled out in front of you at the 8km mark and scared the hell out of you and the HR jumped to 153. Anyway great backyard science and an interesting read. I tried something similar with bearing rolling resistance in my garaage where I spun a front wheel whilst it was in the bike. Each wheel was hand spun to a speed of 20km/h (front wheel Cateye computer) and then timed to when it stopped. The short story was my campag Bora wheel won out by going for over 6 minutes, my Mavic Kysyrium SLR (with special ceramic bearings) went for 3.5 minutes and to my surprise a brand new pair of Shimano Durace deep dishes only went for 1.5 minutes. Boyd reckons it takes new wheels a little time to “bed in” with all the new grease etc..,and I think he may be right.

Anyway for your next project could you shave the hair of the back of your knuckles,trim your nose hair and pluck your eye brows before the next Beach Road PHD.

Look forward to reading your next trial as I’m going mad lying on the floor with two sore hips waiting to get better. I have 3 weeks school holidays and am bored on Day 2.

Tom From Tigerland
tom crebbin says:

June 26, 2012 at 4:34 pm

I’m guessing that “Craig” is Crag Rosenmoots the Fireman as he is an avid Clinchers man. I love a fast single as they just have a bit of life about them like having a Juddy or a Dustin Martin at the centre bounce. I wouldn’t rate the Conti 4000 clincher as the liveliest tyre of all time but love them for training durability. Bit like Dustin Fletcher. Reliable, strong and can play both small and tall.
Big says:

June 26, 2012 at 7:20 pm

Great to hear the ops went well Tommy. I am sure you will understand when I say that I am particularly interested in hearing how your rehabilitation goes…ingredients of another article I think.

Yeah I am not sure about the max HR of 153. I am pretty sure it was only a quick spike, I put it down to being the second run (getting tired). I probably should upload my garmin data for a true speed comparison. I think simply running the test again with the sequence reversed should decide it once and for all.

On the rolling resistance – seriously? You have too much time on your hands. I knew a guy once who was racing on the track and used to grease his bearing with vaso (no his bearings) due to it’s lower viscosity. Maybe, during your time off you could try this theory.

Good to hear from you