Would like some advice whether I should consider changing out the rear cassette on my bike, in anticipation of an upcoming Ironman 70.3 which is about a month away. The bike course is known to have some rolling hills…I think a few may be steep, but not a huge amount of total climb – approx 1000m elevation gain over 90km.
I currently own 2 bikes - my road bike is geared with a compact (50/34) chainring and a 12-30 rear cassette (Shimano 105 components). My tri bike is geared with a standard (54/39) chain-ring and a 12-25 rear cassette (Shimano ultegra components). My current plan is to ride the Tri bike for the race but I have noticed that every time I go to do a training ride that involves hills, I instinctively reach for the road bike. Its easier to ride both on the gearing (I can get up most hills, albeit slowly) and also on the handlebar locations (shifters & brakes in same spot). On the road bike, I lose my pedal power at around 50-55km/h (pretty easy to hit esp with a little hill help, but not sustain). My top speed on the Tri bike is higher & I don’t think I really ever hit a point where I can’t pedal any more.
I am absolutely a weak climber (and faster on the descents) vs the rest of the group that I ride with where I am pretty well matched otherwise. Thanks to body weight for that!
This has got me wondering whether I should consider putting a different rear cassette on the Tri bike to give me one or two more low gears on those hills. I have looked at a few gear ratio charts online but I don’t really know how to interpret the numbers.
Which race? The steepness of the hill matters more than how long it is. IMLP, for example, has some long hills but nothing really steep.
It sounds like you prefer the low gearing on your road bike. No reason not to put it on your tri bike if it helps you, whether physically or just mentally. You don’t want to push to hard struggling to climb a hill in a tall gear. There’s no shame in spinning up the hills.
I’m not really qualified to offer advice on gearing other than to say, especially in long course, better to have a gear and not need it than need a gear and not have it
I had a compact put on my tri bike, and then bought a road bike with compact installed. If it were me, and money were not an issue, I’d have a compact put on the tri bike, then you could swap the 12-30 with the 12-25 for that race. Unfortunately with the compact you do tend to spin out a bit quicker but for me if I am going much more than 35 I’m coasting anyway. I have a few different cassettes that I swap depending on terrain, 12-23 for Miami, 12-30 for IM Canada, 11-28 for Chattanooga, etc. Cassettes are relatively cheap. If you are as you say a weak climber a compact is a wise choice.
At the very least I’d swap out the cassettes and see if that helps (assuming you can with the rear derailleur, but I’ve not had issues going 12-25 to 12-30 and back)
It also depends how the 1000M elevation is laid out. Lots of rollers, or a steep climb or two? 1000M isn’t terribly hilly for a pure cycling course but it’s pretty good for a tri course… it’s more than Wildflower and OCeanside which are considered a bit hilly
And ETA re a comment above, IMO not only is there no shame in spinning up a hill, it’s the smart thing to do
Thanks…bit of a lightbulb moment here…I’d have to check compatibility between the 105 set and the Ultegra set, but I suppose I could at least try moving the rear wheel of my road bike over to the tri bike for a ride to see how much difference it really makes before I start buying new components. Switching out the crankset of course will be more meaningful.
I did it the easy way. I have 3 bikes and 4 sets of wheels. I made everything the same. Hills or flats, I never have to change anything.
All are 50/34 compact, 11/32 cassette, 200mm cranks.
Makes it so I have one less thing to have to worry about for a race.
Being over-geared in a race is not a great idea so if you are concerned that may be an issue I would definitely be adjusting my gearing. Personally, however, I’d go for moving the Compact chainset to your tri bike as I hate having big jumps between my gears, and a 39:30 is pretty similar to a 34:25. If you’re spinning out a 50:12 then you’re probably better off tucking up a bit, freewheeling and saving your energy for the climb when it will have a greater impact on your overall time and trying to kill it on the downhill. Some people obviously don’t mind big jumps between gears, as evidenced by all the 1x discussions, so… With either option their is a good chance that you may need to change the chain length, but unless you want to replace the chain it is easier to take chain out than add it. You may also need to drop the front mech a couple of mm if you swap chainsets, but this is all of 5 mins work.
Why would you want 3 bikes that are all the same? Just curious, coming from someone with 5 bikes (that all have their own unique job, or so i’ve convinced myself anyway). I guess I could see having 2 identical if you want a race bike and a backup, 3 seems a bit overkill
Why would you want 3 bikes that are all the same? Just curious, coming from someone with 5 bikes (that all have their own unique job, or so i’ve convinced myself anyway). I guess I could see having 2 identical if you want a race bike and a backup, 3 seems a bit overkill
They are not all the some. One is my older round tri bike. I then bought 2 Cervelo P2’s. I take them both to race so that if one has an issue, I can use the other, or parts,
which I have already done for one race when I had a wheel issue before race start
I also can use the second P2 for outside training rides, if I ever do one again, , without having to mess with wheels, etc of my race bike.
You only live once. If I find another P2 for a good price I might buy a third.
Yes. Do it. Get an 11-28. I did Tremblant (a quite hilly course) with an 11-23 and regretted it. Bike was fine. Run afterward, not so much. The only issue you’ll get with that spread of gearing is you’ll have bigger gaps between gears. So you may find sometimes it’s harder to hit that perfect sweet spot.
Assuming your R der on the Tri bike can work with a 30t cassette, just swap the road bike cassette onto the tri bike.
Done.
A 34-30 ratio like you have on your road bike is pretty insane.
That’s like Mt. Washington hillclimb gearing.
IF the wheels are similar on both bikes, you could just swap the R wheel from the road bike onto the tri bike.
(if the tri bike wheels are deeper/race wheels, then just do the cassette as I said initially)
If the tri bike R der. doesn’t work with 30T, then go buy a 28T or 27T cassette.
OR - you can buy 2 or 3 of the exact same bike. :-p
