DJKTri

So I have a Tri event coming up in a little over a week.. as I mapped out the course, I noticed the climb was a little longer with elevation than I expected. About 2 mile +8 -to 9%

I have a Giant TCR Composite 2 w/ 9 speed Shimano Ultegra Components. I'm not an expert cyclist, so I apologize If I'm missing any crucial info.

I just put a 12-27 cassette on in place of the 11-23. The chainring is 53/39. My rear derailleur is an Ultegra RD-6500 which will only go up to 27/28 if I recall.

So.. advise if I want to get some better hill climbing gears. Can I try a 12-30 cassette (squeeze it in)? Do I need to get a pickup a different derailleur and get maybe a 12-34. Or.. different chainring?

Trying to determine best course of action and parts needed as this is getting close.

burnthesheep

For tri you are spending extended durations at a lower power output intentionally to pace the event with finishing the run strong.

Given that, the advice on Slowtwitch for years has been to cram whatever necessary on there so that on the climbs you can maintain your target power AND your desired cadence AND desired riding position (not standing, but spinning).

I have no idea how strong you are, but I'd ask around town to see if you could borrow a smaller crank also. Any old hollowtech should do fine. Somebody should have a 50/34 you could use. Since the spacing is the same you'd just have to lower the FD down some for the smaller rings.

Then, I'd see if you can borrow an 11-30 to try. The old largest was a 28t cog on short cage RD's, but some people had success just barely squeezing in the newer 11-30 cassettes. Shimano is pretty conservative on the largest cog thing. Worth a shot.

That's what I'd do:
-borrow a 50/34 crank
-buy/borrow an 11-30 cassette or 11-28 if it won't work

Going as large in back as 11-32 or 11-34 or 11-36 would require a different RD. Which would be tough as you'd need to probably go into the MTB world of used RD's still road compatible to work with your shifters. As the newer "road" stuff that goes pretty big in back is now 11spd.

terrymorse 

People have different gearing needs when it comes to climbs.

Personally, I wouldn’t want to climb 9% grades with a 39/27 combination.

Your easiest change is probably a compact crank set. Shimano still makes a 9-speed Sora model, and it’s not too expensive:

https://bike.shimano.com/en-EU/produ...0/FC-3550.html

Doomrider74

I'd get a 105 compact chainset: 105 is the best value chainset Shimano do, IMO, and you're not adding much weight to the bike.

DJKTri

I have coincidently have a Trek speed concept with 50/34. I'm not comfortable climbing on a tri bike so sticking with the road. Not sure how interchangeable these are as most components on the speed concept are SRAM. Also this is 2x10 speed

The 11 28 is already on. I guess the question is whether I should buy a cheap 11-30 and try squeezing that in.

Iride01 

Is this someplace to out of the way or far from you to just drive there and ride the climb a time or two? First hand experience will give you a reasonable idea how much lower gearing you might need than I can.

spelger

Good idea. and with the wonders of smart trainers the grade profile can be programmed so you can at least simulate it.

DJKTri

I have climbs very close to me. One is around 7% for a mile or so, the other 11%.

datlas 

Lots of options but kinda close to the event.

Last minute futzing around with your equipment is a BAD idea.

DJKTri

True but still, anything to reduce load on legs over a distance will help.. especially as after the 27 biking, still a 10k run. The showed the map as a pdf which made the elevation over distance sorta hard to judge. I took the initiative to plot the course out and was like... oh crap.

I guess the question I have is.. can I just buy the chainrings rather buying a whole new crank etc..? Trying to make this simple. Might even grab a 12-30 just for safe measures.

terrymorse 

Almost certainly not. The bolt circle diameter (BCD) is different on a standard (130mm) and a compact (110mm) crankset.

DJKTri

Which I actually just realized..

So that's takes me back to some of the initial suggestions.. I will be trying a similar climb today just to get the feel.

So I could buy a new crankshaft 50/34. I assume 170mm.

Or..

I could pull the crank off my Trek Speed Concept and install on my Giant TCR Comp 2

What I'm trying to understand is the BB30 compatibility. How you can you tell?

stevel610 

With it being a week out I wouldn't change anything. Your body and muscle memory is used to what you have. Going to a 30t cassette would only lower you about 3 gear inches. Just go out there and have fun, and make changes for your next race.

WhyFi

Frankly, it's easier to swap out a whole crankset (assuming that it's also a Shimano) and it's usually not much more expensive than just the rings, heck - it could even be cheaper, in some instances.

terrymorse 

If 170mm is your existing crank length, yes. It's best not to switch to a different crank length. Ride what you're accustomed to.

The important things are the cranksets' spindle diameter and length. If they match, they are interchangeable. If they are different, they are not.

Iride01 

Practice running with the bike on your shoulder! <grin>

Good luck and enjoy the event when it happens.

Racing Dan

Not knowing your weight, target power and target cadence makes answering your question a complete guessing game.

Assuming your 175 lbs, your bike is 20 lbs, your power is 300W, the incline is 8% and the target cadence is 85 rpm, - your speed will be ~6.3 mph. For that to happen at ~85 rpm you need a 34t chain ring and a 11-36t cassette (!)

Now fill in you own numbers and your own compromises ;-)

Dean V

Ride the TT bike.

deacon mark

If you have to deal with a 2 mile climb at 8-9% then I think you need lower gearing. I am a bit old at 59 but a strong cyclist at least generally but not a great climber. Climbing can be improved with practice and technique as it involves being in shape but you also have to work the gears correct and distribute the energy over the whole climb.

Than said if you are in a Tri race you probably don't want to spend huge time on training that one climb. I would want a compact crank with a 34/32 and spin up the puppy. I would at least need a 34/30 to feel confident and at 34/28........well I might have to walk that is a steep grade for 2 miles.

DJKTri

So what I did was order 2 cassettes. A 30 and 32. I also ordered a wolf tooth roadlink. It supposedly can push the derailleur out to fit differerent cassettes. Really I think the 30 will be fine. But if I can use the 32, I'll take it. Since we got into the metrics.. I'm 155lbs and 5'7.

After this climb is another 12 miles (rolling hills), followed by a 10k. I'd like to not destroy my legs at the halfway point during this climb. Also, I don't wanna get forced out of the saddle, which could happen as a brief part hits +10%.

billridesbikes

I think 30 will be fine. In Tri the race is won or lost in the run. If you finish the hill a minute off from others it’s not a deal breaker, but if you ruin your legs that will be another story. Set an alert on your bike computer so you can to pedal a bit harder right before the start of the steeper grade sections so you have a bit of momentum going in. Slide back in the saddle and engage your glutes (cycling uphill is done with our ass, haha).

Dean V

Remember to check that the chain is long enough to run on the big/big combo.

CliffordK

One thing..

You can adjust the B-Screw on the derailleur and look at the clearance above the sprocket.

Also look at how much the cage is stretched in different gearing combinations (Big/Big, Big/Small,Small/Big, & Small/Small) (which may stretch more with the new sprockets).

Since the chain wraps around about half of the different sprockets, adding 2T will about 1/2", or 1 link more chain.

Circumference = πD = 2πR.

So, adding 2 teeth (1" circumference) will increase the diameter of the sprocket by about 1/π, or about 1/3", and increase the radius by about 1/2π, or a little more than 1/8".

Anyway, you may be able to determine if it looks like you'll have the clearance to try.

Lazyass

This. You can also buy a longer 25mm b-tension screw. Wolf sells them as well although it would be too late for the OP to order that.

ZHVelo

You want to do 2 miles at 8.5% gradient with 39/27? Unless you are real strong, good luck grinding that out.