pjcampbell

I am looking to try the track in 2 weeks at Trexlertown at the "Regionals".

I am confused about gearing and will not really have the opportunity to try it out to figure out which is correct until race day

On fixedgearfever.com there is a program (https://www.fixedgearfever.com/module..._op=getit&lid=) that says a 03:45 3k with 49/15 is 114rpm.

FWIW I have 14, 15 and 16t and 49t chainring. I don't want to buy a new chainring this year.

03:45 3km comes out to about 30.6mph once you are up to speed (last 2666 meters at 30.6mph and 30 seconds for first 333 meters).

https://home.earthlink.net/~mike.sherman/shift.html says that 700x23 with 172.5mm cranks with 49/15 is only 29.3 mph which obviously is a huge difference between the above spreadsheet which suggests that 49/15 is 30.6-7 mph @ 115rpm.

It says that 49/14 @ 115rpm is 31.4mph. 49/14 @ 112rpm is 30.6 mph.

I am actually on 700x21 tubulars so even a little slower (or faster RPMs)

I'm comfortable around 115 RPM but not higher, and most comfortable around 112RPM right now, and trying to decide between 49x14 and 15.

sideshow_bob

I don't think most people are going to be able to give you really specific advice without knowing what your riding ability is.

In my own experience in individual pursuit, sub 3:50 is a pretty decent time here at the state masters level. The guys riding those times pretty much universally are on a gear between 94" and 98". There might be the odd guy riding a tiny bit smaller or bigger. That's on a 250m indoor velodrome.

The gap in gearing between 49/14 and 49/15 is 94" vs 88" and that is a massive difference.

Personally I find myself on 96" or 98" in an individual pursuit and 98" or 100" in a team pursuit.

carleton

Have you been on the track before? If not, are you sure that you will be able to compete? Regionals (or any competition) is not the time to "try the track".

Do you have a USA Cycling License? Are you at least Track Category 4? If not, you won't race.

pjcampbell

Thanks for the replies. I have been to the track 2x only and am a cat4 by doing an upgrade clinic. My CP4 is very decent and my aero is very decent and I have plenty of TTing experience but putting it together will be difficult with little track experience.

What I do mainly do not understand is which RPM calculator is correct, if either? I have tried another one (https://software.bareknucklebrigade.c...it.applet.html) which agrees with Mike Sherman's calculator and disagrees with the Fixed gear fever calculator. It could be that the FGF calc is doing "average RPM".

FGF calculator essentially says 49x15 is 30.6 mph (by virtue of it saying that 49x15 @ 115rpm is 03:45, assuming a constant lap time and therefore constant RPM for the final 2666 meters), the other says 49x15 @ 115rpm is 29.3 mph. These are hugely different and if I can only do 115rpm and 49x15 at 115rpm is 29.3mph no way I will ever do a 03:45 (more like 03:55).

Basically I don't want to undergear myself and find myself sitting there spinning a too easy gear and so I am leaning toward the 49/14 since I have more data supporting that is correct than the FGF one and also appreciate the info that most guys are running 94"->98" in that time range. Like I said I train up to about 115rpm but not faster.

It is a 333 track. The "regionals" just happens to be the only time they actually do TT races.

Dalai

Personally would suggest 49*15 is way undergeared. Of the last couple of 3K pursuits I've done I ran 49*14 outdoors on concrete on a 307m track and at our Nationals ran 50*14 indoors on a 250m timber track and rode a 3:41.7...

chas58

Built track bikes like the Felt T3 typically come with 48/15. beginners do well with a 48/16. If you are in good shape, 48/14 can work too.

Ideally you would have some practice/training sessions and get your comfort level with the track, bike, gearing. We are talking ~$20 for a cog. Get both the 14 and the 15 and see which one you want.

carleton

The FGF calculator is doing average RPM. So you will have to take into account starting at 0 rpm.

pjcampbell

thanks. that makes more sense.

49x14 it is.

Dalai

Best of luck. Look forward to hearing out it goes!

ultraman6970

52x15 is kind'a the usual i have seen so far.

chas58

you guys are both quoting ~94 gear inches either way (49x14 or 52x15)

pjcampbell

well I had a disappointing 3:58.

I think that I am capable of better, but maybe not not capable of the 3:45 I originally thought. I think the gear choice was part of my problem.

Went with the 49x14 and I think I was only doing 105rpm which felt sort of like I was in slow motion!

Overall i felt like I was not giving more than 85% but just couldn't push the pedals faster. I have done plenty of all out efforts as well as plenty of 4 minute @ 400 watt efforts and this did not feel like that. When I attack at the end of a race for 4 minutes it's usually 112-116rpm.

I know 400 watts with decent aero could yield at least 3:50 if not faster? Not sure if this is just lack of experience, poor gear choice, etc. Would like to try to get back to the track with the 49x15 to see where that puts me. Maybe 3:50. I was thinking about getting a cyclometer that'll graph (not just give average) of speed and cadence over distance to really help hone in on what I am really doing out there.

TejanoTrackie 

Going from 49x14 to 49x15 is a huge change in gearing. You need to get 48T and 47T chainrings to fine tune your gearing. When I change gearing it's only 1 chainring tooth at a time. One (1) tooth on a cog = three (3) teeth on a chainring.

pjcampbell

Yeah it is a huge difference but I know 49x14 did not work. RPMs were way too low @ 105rpm.

If I go 49x15 and try for 116rpm that is almost a full 1 MPH faster ,that'd put me around 3:52.

If I felt like I spin out with the 49x15, then I can start fine tuning... like going for a 50x15, that is a 3:47.

Also learned that I want to pedal faster on the track than on the road.

I am definitely going to need some chainrings to get myself exactly whre I want to be but I'd rather test out the 49x15 and confirm I can do a 3:52 with no problem before assuming I can go faster