It’s Mt. Diablo Hillclimb TT time again. Practice 2

I had decided to try a 18t this week and even though I had a brand new spare Shimano 18t freewheel in the toolbox I couldn’t bring myself to use it on my race bike.  I normally exclusively use White Industries ENO freewheels for my hill climb bike but I just couldn’t afford keep buying different sizes for different gear rations so I went with Excess Components 3/32 freewheels instead. I was able to buy 5 of these for the price of one White Industries cog on sale from Amazon. I was really hoping they were not the junk that the Shimano freewheels are (I do use these on my commute bike but they develop a lot of play pretty quickly) or even worse the ACS freewheels I tried. I tried two ACS freewheels on my single speed CX bike and one started slipping after riding in the rain just once. The second one worked better but sounded horrible after only 500 miles and my chain kept derailing (a problem I have never experienced on any other freewheel on my commute bike). The spec of the Excess sounded very encouraging:

 Excess Components Single-Speed Freewheels

  • Cold forged from 4130 chromoly
  • 3 heavy-duty fast engaging/releasing pawls
  • 30 Points of engagement for an instant and reliable start every time
  • Show chrome finish on the outside, titanium finish in the center
  • 8-spline body for weight savings and easier removal with standard tool

FREEWHEELS — White Industries

The freewheel utilizes a sealed cartridge bearing instead of a loose ball system. There are two advantages to the cartridge bearing:
•It is sealed from elements like mud, grit, and water.
•The bearing is nicely contained in one simple unit, easily pulled and replaced when worn.

The ENO freewheel features a machined inner driver and machined outer gear case resulting in a freewheel that runs concentrically without the tight and loose spots common to other freewheels. A 36 point engagement system and a case hardened, nickel electro-plated outer gear case make this freewheel a perfect addition to your single speed. For trials riders or those wanting a beefier version we offer the trials freewheel with 72 points of engagement and a thicker outer gear case to withstand the rigors of a more demanding style of riding.

The good news is although they do not feel quite as smooth or tight as a White Industries freewheel and the chain is a little noisier they actually feel great with a crisp engagement and good freewheel (time will tell how reliable they are). The finish is also not as good as the White Industry but you can find them for about 1/5th of the price on sale so they are definitely worth the risk. Long term report to follow.

I was expecting big things with this change to a bigger gear in terms of my overall time. I hoped that the 1.4MPH gain at 100rpm would translate to a similar improvement over the first 1.5 miles with a corresponding 0.5MPH improvement in the overall time. My theory was that I was losing a lot of time through spinning out the 32 x 20 but I should still be OK on the steeper stuff on a 32 x 18. What I actually achieved was a nearly 30 second slower pace over the 1.5miles which led to a deficit of nearly a minute by mile 3.5 and finishing up with a deficit of 33seconds by the top. I was not a happy bunny.

Comparison of 32×20 ride to 32×18 ride (pink)

I have adopted single speed for hill climbs based on the mechanic simplicity and purity of the experience. I also enjoy the challenge of figuring out the optimum gear for the climb and the joy of riding an “old school” steel bike . Having said that, I am pretty disappointed with my lack luster performance on the single speed on this climb. In theory I can expect to lose 5 seconds per mile simply due to the weight difference between my Carbon Tarmac and steel Wabi which would make me just 30 seconds slower than the carbon. Unfortunately I am losing 30s per mile throughout the course (over 3 minutes slower in total) which is a huge loss. I thought even with the disadvantage of Steel and Single speed I would be able to do a time that wouldn’t put me in last place. I am not sure my ego can handle last place :+)

I felt it was possible to get within 1-1.5 minutes of my p.b with the fixed setup and to do this I though all I needed to do was up the gear. I assumed lack of gearing was my issue over the first 1.5 miles but even with a bigger gear the headwind was a significant enough factor that I was nearly 1MPH slower to mile 1.5 (The wind was definitely harder this week). The first section is a big problem On my geared bike I can set off in a controlled fashion and ease into the TT with a pretty high average speed. On single speed I need to pedal furiously to keep up a half way decent speed and I also have to freewheel down the little drop just after the start. I think this may be having an impact on my performance later in the climb which is why even when the gearing isn’t an issue I am still losing 30s per mile. Backing off more at the start simply isn’t possible so on the day I will have to do a super warm up so I am zinging right out of the starting gate.

Black line = PR on Carbon tarmac with Gears, Blue line = 34×18 Wabi Steel , Purple line = 34 x 20 Wabi Steel

Surprisingly the bigger gear didn’t actually feel all that bad and on the hardest section of the climb I only lost 5s to my previous 32 x 20 attempt (14 seconds slower than my PR). I did however have to do the entire climb out of the saddle which took quite a lot out of me and my arms began to ache a lot.

The Steepest Bit : Black line = PR on Carbon tarmac with Gears, Blue line = 34×18 Wabi Steel , Purple line = 34 x 20 Wabi Steel

The trace below comparing 32×20 (purple) and 32×18 (Pink) shows  I was definitely suffering more as the climb went on. It does have to be noted that there was a noticeable headwind on the climb this week so this may be why I had the 5s difference. Expanded view just showing the two single speed attempts below.

Comparison of 32×20 ride to 32×18 ride (pink)

I fitted a cadence sensor and saw some very low cadence numbers on parts of the climb (low 60’s)  so I don’t think upping the gear any more will achieve anything other than destroying my knees.  The other variable I haven’t really been able to quantify is my fitness in relation to last year.  As I haven’t the option of a power meter I can really only go by how I feel.  I would say I feel pretty fit and my weight is quite similar to last year but I haven’t had the quality of racing.  Quality racing really teaches you how to suffer so perhaps I am not pushing myself as hard as I could. On my final practice before the big day I am going to concentrate on better pacing to take advantage of the 18t gear and trying to push a bit harder.  Perhaps a skin suit on the day may gain me a few seconds too.

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