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Running a compact crank on a tri bike
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 2010-11-04 10:04 AM |
Veteran  503  Bedford, NH |  Subject: Running a compact crank on a tri bikeI am in the process of ordering my first tri bike (2011 Felt B12). I believe it uses an SRAM Apex Crank with a 53/39 Red chainring and a 11/26 cassette (rest of the drivetrain is SRAM Red). On my road bike, I use a SRAM Force 50/34 with an 11/26 and went with this because it is hilly where I live. I was thinking about swapping the 53/39 on the tri bike with a 50/34, perhaps using the Force version. Although it looks like the Apex version uses a 110mm BCD. Is there a reason why I should not swap for a 50/34 on the tri bike? If I do this, would I be better keeping with the Apex or switch to Force for the crank. Hoping I can still use the Red chainring on either of these options. |
| 2010-11-04 10:11 AM in reply to: #3194786 |
Extreme Veteran 562 | Subject: RE: Running a compact crank on a tri bike Funny thing, my Cervelo came with a compact. Trained and raced for the last 3 years on it. This year, I put my old Trek on the trainer with a "standard". No big deal until I took the Trek out for a ride and really liked not having the compact. So I just had a "standard/non-compact" installed on my Cervelo. Unfortunately the weather has turned to crap here in NJ, so I have not tried it. So short answer, go with standard, even in hilly areas. IMO. Edited by randym 2010-11-04 10:17 AM |
| 2010-11-04 10:17 AM in reply to: #3194786 |
Master 2020 | Subject: RE: Running a compact crank on a tri bike mjengstrom - 2010-11-04 10:04 AM I am in the process of ordering my first tri bike (2011 Felt B12). I believe it uses an SRAM Apex Crank with a 53/39 Red chainring and a 11/26 cassette (rest of the drivetrain is SRAM Red). On my road bike, I use a SRAM Force 50/34 with an 11/26 and went with this because it is hilly where I live. I was thinking about swapping the 53/39 on the tri bike with a 50/34, perhaps using the Force version. Although it looks like the Apex version uses a 110mm BCD. Is there a reason why I should not swap for a 50/34 on the tri bike? If I do this, would I be better keeping with the Apex or switch to Force for the crank. Hoping I can still use the Red chainring on either of these options. I am going to say up front without knowing the bolt pattern of the Force crank its hard to say. I have seen a 110BCD with a 53/39 on them. If that is the case then they will work. If the Force crank is a 130BCD you can not use the rings on it. But as for which is better the Apex crank is going to be stiffer but the force crank will be lighter. |
| 2010-11-04 10:24 AM in reply to: #3194807 |
Champion 11989   Philly 'burbs | Subject: RE: Running a compact crank on a tri bike randym - 2010-11-04 11:11 AM Funny thing, my Cervelo came with a compact. Trained and raced for the last 3 years on it. This year, I put my old Trek on the trainer with a "standard". No big deal until I took the Trek out for a ride and really liked not having the compact. So I just had a "standard/non-compact" installed on my Cervelo. Unfortunately the weather has turned to crap here in NJ, so I have not tried it. So short answer, go with standard, even in hilly areas. IMO. Note the location  Jersey is pretty flat, especially compared to NH.I run a compact on my tri bike and love it. I also just upgraded my road bike from a triple to a compact. I will say though, that I've never run a standard on a road bike. I've had bikes in my youth with standard cranks, and currently have an old steel Huffy with a standard, but have only ridden a standard for fun and recreation. Never for serious training or racing. No opinion on particular parts fitting together |
| 2010-11-04 11:01 AM in reply to: #3194786 |
| over a barrier | Subject: RE: Running a compact crank on a tri bike |
| 2010-11-04 11:41 AM in reply to: #3194786 |
New user 42 VA | Subject: RE: Running a compact crank on a tri bike 95% of people would probably be better served riding on a compact crank on their tri bike. With the way triathlon theory is moving toward faster cadences, a compact will help more riders achieve the aerobic cadences we're all after.If you look at the hour record, which is one of the paramount events showcasing time trialing ability, only once in the past 50 years or so has the record been set with a cadence under 100. |
| 2010-11-04 12:33 PM in reply to: #3194786 |
Master 1366 PNW | Subject: RE: Running a compact crank on a tri bike I find this thread very interesting. I just bought a QR Seduza and it came with a 50/34 compact crank. I'm in the process of switching it for a 53/39 standard double. Am I wrong to do so? My longest tri distance in the forseeable future is Oly, if that matters. |
| 2010-11-04 12:50 PM in reply to: #3195170 |
Extreme Veteran 5722 | Subject: RE: Running a compact crank on a tri bike My decision to go compact was very simple. I tried seeing how much power I needed to go up 12%-17% grades. It was way above the 80% of FTP I wanted to maintain on a HIM, even with a 12/28 on the back. So I decided to go compact. If you never plan to train/race hills, it's probably not even an issue, but eventually I would like to do LP, St-Croix and maybe one day Israman, all very hilly courses. I figure with a compact I have better ranges for various races, playing with various cassettes. |
| 2010-11-04 12:57 PM in reply to: #3194786 |
Veteran 503 Bedford, NH | Subject: RE: Running a compact crank on a tri bike It looks like the SRAM TT Chainring, does not come in a 50T, only a 53T (or 554, 55). So if I switch to compact (either Force or Red), I would loose ability to use that. I assume the aerodynamic advantage of the TT chainring doesnt outweigh switching to compact non-TT chainring? I think I am leaning towards switching to the Force Compact and keeping the 11-26 in the back. GLC1968 - 2010-11-04 1:33 PM I would think it would also matter what cassette you plan to use. If you are running out of gears on a 52, I would guess your smallest ring on the cassette may be a 12 (or larger), either that or you are a very strong cyclist or have lots of downhills. Perhaps changing this to an 11 would be easier than changing the cranks. I find this thread very interesting. I just bought a QR Seduza and it came with a 50/34 compact crank. I'm in the process of switching it for a 53/39 standard double. Am I wrong to do so? |
| 2010-11-04 12:59 PM in reply to: #3194786 |
Extreme Veteran 586 Richmond | Subject: RE: Running a compact crank on a tri bike 4 watts/kilogram as a rule of thumb for when to move to a standard crank. Obviously if you live in a flat area you can get away with a standard more of the time. But in general, that 4 watt/kg rule is a great guide. With a good position, 4 watts / kilo is top 3 overall bike split at local races. With a great position, it can often be the fastest bike split. Since most triathletes will not get to that point, most triathletes belong on compact cranks. Like 95-99% of us. Just to keep this all in perspective, 53/39 with an 11-23 cassette is what TdF level riders use. They will go to a 12-25 on mountain stages. These guys are almost all at 5.5 watts/kilo or above. |
| 2010-11-04 1:09 PM in reply to: #3195239 |
Veteran 503 Bedford, NH | Subject: RE: Running a compact crank on a tri bike Thanks Dave! That is very helpful to know and confirms my decision to swap out to a compact. I am not quiet at that level. I think I am around 3.3 watts/kg (based on avg watts on a computrainer last winter). I dont actually own a power meter now. |
| 2010-11-04 1:13 PM in reply to: #3195260 |
Extreme Veteran 586 Richmond | Subject: RE: Running a compact crank on a tri bike Here is an even easier rule of thumb with no power knowledge required: You should use all of the gears on your bike. So the biggest climb you regularly see should have you in your smallest gears. The biggest descent should find you in your biggest gears. If most of your riding finds you towards one end of your total gearing range or the other, consider some gearing changes. |
| 2010-11-04 1:14 PM in reply to: #3194786 |
Expert 798 Kewaunee, WI | Subject: RE: Running a compact crank on a tri bike I had a compact crank. I hated it. I live in a hilly area and race a lot of hilly races. One can only go so fast down a hill on a compact. It drove me nuts. My cadence is not as high as it should be, or is *supposed* to be. I don't think there is a study out that that has shown definitively that riding with a higher cadence is better than riding with a lower cadence like mine. I say buy the bike with the 53-39 and if you find you want a compact I will sell you my gently used FSA compact for cheap.  |
| 2010-11-04 1:15 PM in reply to: #3195216 |
Champion 9060 Charlottesville, Virginia | Subject: RE: Running a compact crank on a tri bike marcag - 2010-11-04 1:50 PM My decision to go compact was very simple. I tried seeing how much power I needed to go up 12%-17% grades. It was way above the 80% of FTP I wanted to maintain on a HIM, even with a 12/28 on the back. So I decided to go compact. If you never plan to train/race hills, it's probably not even an issue, but eventually I would like to do LP, St-Croix and maybe one day Israman, all very hilly courses. I figure with a compact I have better ranges for various races, playing with various cassettes. Exactly but if you don't have a power meter. Another good way to think about it is how many times do you wish you had a bigger gear going down hill vs. how many times have you clicked and then looked down at your casette just to check for the 5th time to make sure there aren't any more gears left when you're going up a hill. Edited by dalessit 2010-11-04 1:16 PM |
| 2010-11-04 1:18 PM in reply to: #3195273 |
Not a Coach 11473 Media, PA | Subject: RE: Running a compact crank on a tri bike TracyV - 2010-11-04 2:14 PM One can only go so fast down a hill on a compact. Yes, I've only managed to go about 52mph downhill on mine. Really sucks. |
| 2010-11-04 1:20 PM in reply to: #3195170 |
Regular 233 NW | Subject: RE: Running a compact crank on a tri bike GLC1968 - 2010-11-04 10:33 AM I find this thread very interesting. I just bought a QR Seduza and it came with a 50/34 compact crank. I'm in the process of switching it for a 53/39 standard double. Am I wrong to do so? My longest tri distance in the forseeable future is Oly, if that matters. If you are running 650s, you effectively are running a compact crank . A standard 53 on a 650 wheelset would equate to a 49 on a 700 wheelset. |
| 2010-11-04 1:25 PM in reply to: #3194786 |
Expert 1002 | Subject: RE: Running a compact crank on a tri bike I've personally found that compact cranks leave me spinning out on descents and with plenty of gears on the cassette for the worst (read:best) climbs that I encounter. My typical cadence is around 90-95 and my power numbers are well within my FTP ranges. Here's a nifty calculator that lets you toy around with some gearings with the related speed output. http://home.earthlink.net/~mike.sherman/shift.html |
| 2010-11-04 1:28 PM in reply to: #3194786 |
Veteran 270 Burlington | Subject: RE: Running a compact crank on a tri bike Unless you can outspin a 50/11 gear combo (32MPH @ 90RPM or 43MPH @ 120RPM) save your legs on the hills with a compact crank. http://sheldonbrown.com/gears/ |
| 2010-11-04 2:29 PM in reply to: #3195317 |
Master 1366 PNW | Subject: RE: Running a compact crank on a tri bike UWMadTri - 2010-11-04 11:25 AM I've personally found that compact cranks leave me spinning out on descents and with plenty of gears on the cassette for the worst (read:best) climbs that I encounter. My typical cadence is around 90-95 and my power numbers are well within my FTP ranges. Here's a nifty calculator that lets you toy around with some gearings with the related speed output. http://home.earthlink.net/~mike.sherman/shift.html Awesome calculator, thanks! It confirmed my thoughts - I need a standard double. A compact gives me the exact same low gear as the lowest gear on my road bike when in the middle ring, but the top combination is no where near high enough. It's actually quite a bit LOWER than the top combo on my road bike. Considering that in a race situation on the road bike (no aerobars), I ran out of top end gears (and I'm not a masher) then I DEFINTELY need the 53T on the tri bike. Put me in aero and I'm certain I'm going to need those high gears. No doubt about it. I wish I had a power meter - maybe I'm throwing out some amazing numbers here and I don't even know it! |
| 2010-11-04 2:38 PM in reply to: #3195476 |
Not a Coach 11473 Media, PA | Subject: RE: Running a compact crank on a tri bike GLC1968 - 2010-11-04 3:29 PM I wish I had a power meter - maybe I'm throwing out some amazing numbers here and I don't even know it! If you were throwing out some amazing power numbers on the bike, you would know it without needing a PM. But, as noted before, having 650 wheels plus a standard crank means you are already effectively operating with similar gear ratios as someone having 700 wheels and a compact. Gear ratios are what matter, not what kind of crank you have. |
| 2010-11-04 3:02 PM in reply to: #3195489 |
Master 1366 PNW | Subject: RE: Running a compact crank on a tri bike JohnnyKay - 2010-11-04 12:38 PM GLC1968 - 2010-11-04 3:29 PM I wish I had a power meter - maybe I'm throwing out some amazing numbers here and I don't even know it! ;) If you were throwing out some amazing power numbers on the bike, you would know it without needing a PM. ;) But, as noted before, having 650 wheels plus a standard crank means you are already effectively operating with similar gear ratios as someone having 700 wheels and a compact. Gear ratios are what matter, not what kind of crank you have. That statement doesn't really make any sense since the kind of crank you have is part of the equation that determines your gear ratios. ;) My point is that since I have 650's, I need a standard to get the best ratios. In fact, if you step up a level or two with most of these companies, they DO put standard cranks on the smallest bikes (if they run 650's)...they just didn't make that distinction on my particular bike choice, so I have to do it for myself. Edited by GLC1968 2010-11-04 3:03 PM |
| 2010-11-04 3:12 PM in reply to: #3195534 |
Not a Coach 11473 Media, PA | Subject: RE: Running a compact crank on a tri bike GLC1968 - 2010-11-04 4:02 PM JohnnyKay - 2010-11-04 12:38 PM GLC1968 - 2010-11-04 3:29 PM I wish I had a power meter - maybe I'm throwing out some amazing numbers here and I don't even know it! If you were throwing out some amazing power numbers on the bike, you would know it without needing a PM. But, as noted before, having 650 wheels plus a standard crank means you are already effectively operating with similar gear ratios as someone having 700 wheels and a compact. Gear ratios are what matter, not what kind of crank you have. That statement doesn't really make any sense since the kind of crank you have is part of the equation that determines your gear ratios. My point is that since I have 650's, I need a standard to get the best ratios. In fact, if you step up a level or two with most of these companies, they DO put standard cranks on the smallest bikes (if they run 650's)...they just didn't make that distinction on my particular bike choice, so I have to do it for myself. Sorry, I should have said "by itself" as a qualifier. Of course it is part of the equation. As are wheels and cassette. That calculator allows you to see that clearly. |
| 2010-11-04 6:47 PM in reply to: #3195317 |
Champion 9407 Montague Gold Mines, Nova Scotia | Subject: RE: Running a compact crank on a tri bike UWMadTri - 2010-11-04 3:25 PM I've personally found that compact cranks leave me spinning out on descents and with plenty of gears on the cassette for the worst (read:best) climbs that I encounter. My typical cadence is around 90-95 and my power numbers are well within my FTP ranges. What cassette were you running with your 50 and what are you running with your 53? Shane |
| 2010-11-04 7:04 PM in reply to: #3195270 |
Master 2356 Westlake Village , Ca. | Subject: RE: Running a compact crank on a tri bike Dave Luscan - 2010-11-04 11:13 AM Here is an even easier rule of thumb with no power knowledge required: You should use all of the gears on your bike. So the biggest climb you regularly see should have you in your smallest gears. The biggest descent should find you in your biggest gears. If most of your riding finds you towards one end of your total gearing range or the other, consider some gearing changes. This is what I go by....My gearing seems to suit my training area very well as I do use all the gears quite often. Dave, can you elaborate on why better (more powerful) riders would want higher gearing? I can only assume it would be because they can push highers gears up steeper grades meaning they would never need the lower gears on a compact crank? Is that thinking correct? |
| 2010-11-04 7:17 PM in reply to: #3195884 |
Expert 1002 | Subject: RE: Running a compact crank on a tri bike gsmacleod - 2010-11-04 6:47 PM UWMadTri - 2010-11-04 3:25 PM I've personally found that compact cranks leave me spinning out on descents and with plenty of gears on the cassette for the worst (read:best) climbs that I encounter. My typical cadence is around 90-95 and my power numbers are well within my FTP ranges. What cassette were you running with your 50 and what are you running with your 53? Shane Good point. I was running an 11/23 with my 50 and a 12/27 with my 53. For flatter races, I toss the 11/23 with the 53 now. Didn't even think about that. Not an absolutely enormous difference, but still significant. |
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