Calling on Leegocrap and other bike experts - Help with choosing a rear cog
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General Discussion | Triathlon Talk » Calling on Leegocrap and other bike experts - Help with choosing a rear cog | Rss Feed |
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2015-08-25 2:29 PM |
1300 | Subject: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Not sure this can be easily answered. After borrowing some carbon wheels from a friend I purchased a used set. So with considering what cog to put on I have been debating the difference between what I have on road bike vs tri bike. My probably noob question and definitly noob description is on my road bike I have a 9-spd triple with 12-26 (have to check that tonight) which I ride primarily middle ring and not sure how to describe what gear I use but high as in I have one or two gears to move up if needed. Example tailwind I'll move up at least one. Tri bike I'm riding 10 spd double 11-25 primarily sm ring toward the end, one gear to move up. But I'm either on the edge of cross chaining or am cross chaining. Worse if I move up to big ring sm gear. I like the feel of the gearing I use on the road bike vs tri bike. Just have no clue what cog to get. Wheels are only for tri bike unless I upgrade road to 10 spd. Just to embarrass myself when I looked up my road bike I realized it was only a 9 spd. All these years I thought it was a 10. |
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2015-08-25 2:47 PM in reply to: Goggles Pizzano |
Champion 9407 Montague Gold Mines, Nova Scotia | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog |
2015-08-25 3:02 PM in reply to: Goggles Pizzano |
Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Originally posted by Goggles Pizzano Tri bike I'm riding 10 spd double 11-25 primarily sm ring toward the end, one gear to move up. But I'm either on the edge of cross chaining or am cross chaining. Worse if I move up to big ring sm gear. Just want to make sure I am interpreting this correctly. On your tri bike, you mostly ride in the small chain ring up front, and the smaller cogs (the faster ones) in the rear, thus causing the cross chaining? And if you shift to the big ring up front instead, you are forced to use the larger cogs (the slower ones) which causes worse cross chaining? What are the chain ring sizes on your crank? Is it 50/34? Do you mostly ride in flat areas or do you often ride hills? Do you find that you want more gears when riding hills?
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2015-08-25 3:14 PM in reply to: gsmacleod |
1300 | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Good question and I'll have to double check that shortly when I get home. Tri is a 2014 P2 so FSA Gossamer BBright 50/34 , can't remember length. It wasn't swapped out on the 3 fit sessions I had. Road is Tiagra guessing 172.5 or 175. I just looked at both not too long ago, just can't be sure off the top of head. |
2015-08-25 3:18 PM in reply to: 0 |
1300 | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Originally posted by Jason N Originally posted by Goggles Pizzano Tri bike I'm riding 10 spd double 11-25 primarily sm ring toward the end, one gear to move up. But I'm either on the edge of cross chaining or am cross chaining. Worse if I move up to big ring sm gear. Just want to make sure I am interpreting this correctly. On your tri bike, you mostly ride in the small chain ring up front, and the smaller cogs (the faster ones) in the rear, thus causing the cross chaining? And if you shift to the big ring up front instead, you are forced to use the larger cogs (the slower ones) which causes worse cross chaining? What are the chain ring sizes on your crank? Is it 50/34? Do you mostly ride in flat areas or do you often ride hills? Do you find that you want more gears when riding hills?
Yes you got it and correct 50/34. Pretty much all the races I do are flat. I train in a hilly area part time but typically use road bike for that. If I was on tri where I live I would be looking for more gears. I got used to the triple on hills. Edited by Goggles Pizzano 2015-08-25 3:19 PM |
2015-08-25 3:57 PM in reply to: Goggles Pizzano |
Champion 10668 Tacoma, Washington | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Drop the big ring down a few teeth. I'm running 46/34 on my gravel bike, and when I put it in road mode, I use a 12-23 10-speed cluster for nice tight gearing but still able to take decent hills on the 34. On my road bike I've got 50/34 and a 12-25, and it seems I'm running just a bit left of center on the cluster most of the time in the big ring (which I rarely shift out of on most regular rides). |
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2015-08-25 3:58 PM in reply to: Goggles Pizzano |
Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Looking at gear calculators, I think your current setup should be okay so long as you are shifting properly. 50/23 and 34/12 seems to be the gears you want to ride, but they are cross chaining. However, they are not nearly the same gear. At 85 rpms, 50/23 should get you 14.6 mph and 34/12 should get you 19.1 mph. If you want to simulate the 34/12 gear (19.1 mph) without cross chaining, then switch to the 50/17 or 50/19 gear which is right in the middle of the cassette. You may have to change you cadence slightly to match the same 19.1 mph speed, but it's still a good option rather than riding 34/12. If you want to simulate the 50/23 gear without cross chaining, then switch to the 34/15 or 34/16 gear which is also right in the middle of the cassette. Now if you want more gears for climbing, then obviously choose a cassette with easier gears. Maybe a 12-28. But for flat riding, I think you should be okay with 11-25.
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2015-08-25 5:13 PM in reply to: Goggles Pizzano |
Pro 5361 | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog This guy's page is pretty helpful for comparing cassettes:
http://home.earthlink.net/~mike.sherman/shift.html
Have fun. It really depends on your strength and terrain. |
2015-08-25 5:16 PM in reply to: Goggles Pizzano |
1300 | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Originally posted by Goggles Pizzano Both cranks are 170Originally posted by Jason N Originally posted by Goggles Pizzano Tri bike I'm riding 10 spd double 11-25 primarily sm ring toward the end, one gear to move up. But I'm either on the edge of cross chaining or am cross chaining. Worse if I move up to big ring sm gear. Just want to make sure I am interpreting this correctly. On your tri bike, you mostly ride in the small chain ring up front, and the smaller cogs (the faster ones) in the rear, thus causing the cross chaining? And if you shift to the big ring up front instead, you are forced to use the larger cogs (the slower ones) which causes worse cross chaining? What are the chain ring sizes on your crank? Is it 50/34? Do you mostly ride in flat areas or do you often ride hills? Do you find that you want more gears when riding hills?
Yes you got it and correct 50/34. Pretty much all the races I do are flat. I train in a hilly area part time but typically use road bike for that. If I was on tri where I live I would be looking for more gears. I got used to the triple on hills. |
2015-08-25 5:23 PM in reply to: morey000 |
1300 | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Originally posted by morey000 This guy's page is pretty helpful for comparing cassettes:
http://home.earthlink.net/~mike.sherman/shift.html
Have fun. It really depends on your strength and terrain. Thanks I'll read that tonight |
2015-08-25 5:34 PM in reply to: Jason N |
1300 | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Originally posted by Jason N Looking at gear calculators, I think your current setup should be okay so long as you are shifting properly. 50/23 and 34/12 seems to be the gears you want to ride, but they are cross chaining. However, they are not nearly the same gear. At 85 rpms, 50/23 should get you 14.6 mph and 34/12 should get you 19.1 mph. If you want to simulate the 34/12 gear (19.1 mph) without cross chaining, then switch to the 50/17 or 50/19 gear which is right in the middle of the cassette. You may have to change you cadence slightly to match the same 19.1 mph speed, but it's still a good option rather than riding 34/12. If you want to simulate the 50/23 gear without cross chaining, then switch to the 34/15 or 34/16 gear which is also right in the middle of the cassette. Now if you want more gears for climbing, then obviously choose a cassette with easier gears. Maybe a 12-28. But for flat riding, I think you should be okay with 11-25. Now reading this I'm starting to understand better how to talk about this, thanks. So if I figure out hat the gear combination is on road bike can that be converted? Based on this stick with same cassette and just combing ear combinations? I was thinking a different cassette was answer but that was a guess
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2015-08-26 7:42 AM in reply to: Goggles Pizzano |
Veteran 721 Naptown, IN | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog This may help too: http://www.sheldonbrown.com/gears/ You can input values for each bike and determine "equivalent" gears. |
2015-08-26 9:49 AM in reply to: Goggles Pizzano |
Champion 9407 Montague Gold Mines, Nova Scotia | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Originally posted by Goggles Pizzano Now reading this I'm starting to understand better how to talk about this, thanks. So if I figure out hat the gear combination is on road bike can that be converted? Based on this stick with same cassette and just combing ear combinations? I was thinking a different cassette was answer but that was a guess
Cassettes are relatively cheap so there's no reason not to have a few different ones for different courses and purposes. For example, for flatter races, I have an 11-21 on my race wheels and also have an 11-23 for hiller races. My training wheels on my tribike have a 12-25 and my road bike has a 12-27. A rough guideline for shifting is to go two cogs smaller in the rear when going from a larger to smaller chainring and two cogs bigger when going from a smaller chainring to a larger one. This will usually put to close to the same gear ratio. Shane |
2015-08-26 10:16 AM in reply to: gsmacleod |
1300 | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Originally posted by gsmacleod Originally posted by Goggles Pizzano Now reading this I'm starting to understand better how to talk about this, thanks. So if I figure out hat the gear combination is on road bike can that be converted? Cassettes are relatively cheap so there's no reason not to have a few different ones for different courses and purposes. For example, for flatter races, I have an 11-21 on my race wheels and also have an 11-23 for hiller races. My training wheels on my tribike have a 12-25 and my road bike has a 12-27. A rough guideline for shifting is to go two cogs smaller in the rear when going from a larger to smaller chainring and two cogs bigger when going from a smaller chainring to a larger one. This will usually put to close to the same gear ratio. Shane Based on this stick with same cassette and just combing ear combinations? I was thinking a different cassette was answer but that was a guess
Thanks Shane I realized this morning I could get the same cog I'm running now for $25 on ebay. Last time I was in LBS they wanted over $100 so I didn't want to experiment too much at that time. But you're right, going to try another one out also. |
2015-08-26 12:43 PM in reply to: Goggles Pizzano |
Champion 7136 Knoxville area | Subject: RE: Calling on Leegocrap and other bike experts - Help with choosing a rear cog Already some great info by much smarter guys. I admit, my knowledge when it comes to rear cogs and ratio's really doesn't extend past "Big front small rear fast" |
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