TT's with a compact chainset?

dieselengine

I am going to do my first TT (for many years) this year, (40 this week so time is running out for me!). Starting back with 10s (and quite likely to stay with them!).

Did some 20 years or so ago, since when the old knees have become much more delicate, so I am riding compact chainsets now, with no probs.

I am have a mental block tho' about turning up to a TT sign on, with a 50/34 on. It just seems wrong!

I can spin the 50/14 or 13 combination pretty well, and reasonably quickly, but I'm just not sure. Have tried the 53/39 I have in the garage for a few rides, but cadence is down, and knees are sore afterwards. Should I persevere with the 53/39, or graciously accept I am now a big Jessie who can't turn the bigs gears and stick to twiddling the compacts?

fastcat

I've used a compact 50/34 in TT's. I have a 25/12 cassette on the rear which has been fine. Of course, I'm not breaking any records, but could go to a 23/11 if required I guess. With that sort of combination you could spin the lower gear, but still have a bigger gear available if required.

And don't worry about what anyone else thinks. It's the time that matters!

Mike Willcox

The gear you use is subjective. there is absolutely no point in grinding away in too big a gear because of some mistaken issue re your street cred.

Having a range of gears available seems to make perfect sense. No bystander or competitor will view you any differently to any other rider.

Your top gear @100 rpm = 30 mph. Should be sufficient I would have thought

dennisn

I agree. If, as you claim, you can "spin" a 50-13 "reasonably quickly" you should have no trouble winning it all and making the olympic team. In other words I have my doubts
about your 50-13 claim. Maybe, just maybe, if you're running 650 wheels.

Dennis Noward

mackdaddy

Don't worry about it diesel. I spin at around 105 rpm on TT's so for flats and inclines it doesn't really matter which chainset I use, I just pick the gear that suits my cadence. I don't even know what it is, I just do what is comfortable on the day. I've used both.
The only difference I have found between them is that I run out of spin speed on downhills with the compact so the standard is slightly faster overall.
There's always someone using more and more specific kit than you, such as skin suit, helmet, disc wheels etc, but I've never experienced any snobbery because of it. I used the same bike and kit for TTs as I did for commuting last year and the set up didn't change. I managed to go under 24 minutes last year and I'm aiming lower this year so I've upgraded to aero bars to get the position better, but no fancy helmet, wheels or skin suit. Nobody minds IMO, they are all just racing against themselves anyway. Just enjoy it.

Ian Sims

I think most of us mortals often ride bikes that are overgeared.

I ride my best time trials when I am spinning properly, so 53 x 17 gives me 40 kph at just over 100 rpm. That would be equivalent to riding 50 x 16, so a compact chainset should be fine.

Ian

DaveyL

Yep, unless the TT course has a sustained downhill drag where you could do, say, 35 mph with furious pedalling, you will be fine with a 50/34.

scherrit

We often get ask to prescribe gear set-ups for (non-elite) triathletes and it's well worth doing the gearing calculation for their typical TT speed as above but also worthwhille to try to make sure they have single-tooth differences close to that gear if possible, and if the course permits. In other words, as long as it's not an Alpine TT course ("sporting"!!!!) you might try to be sure that there is a 18/17/16/15 combo mid cassette for a fairly strong (but spinning) rider using a 39/53. The 16 is often missing from wide ranging 9-speed cassette which is a pity as plenty of riders would spend a good amount of time in the 53/16 on the flat when pedalling in anger.
Good luck!
Scherrit.
www.thebikewhisperer.co.uk