Chainring Swap on FSA VERO Compact crankset?
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mstuartev
Jul 29, 2012, 11:25:13 AM7/29/12
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I'm putting the finishing touches on the Pacer 650B conversion. Got the
wheels built and need to change the stem to something more comfortable
for this old man. Plus I have to add some attachment points for a rack
in back.
The Crankset on the bike is an FSA Vero 50/34. I've been commuting
lately - due to hills - on my Jamis Aurora (700C) which has a triple,
but I pretty much live on the middle chain ring and (occasionally) the
granny for extreme hills. In the 7 years since I've owned this
bulletproof bike I can count on two hands the times I've been in the 50
tooth outer chain ring.
QUESTION: Is it unheard of to swap that 50 (outer) with a 42 tooth chain
ring and make it a bit more of a useful crank set up (42/38)? It has
Tiagra drive train and the front Der looks as tho it'd handle it. it's a
110 BCD so I assume I could use any chain ring of that size?
Thanks ahead for any advice Mark E
--
wheels built and need to change the stem to something more comfortable
for this old man. Plus I have to add some attachment points for a rack
in back.
The Crankset on the bike is an FSA Vero 50/34. I've been commuting
lately - due to hills - on my Jamis Aurora (700C) which has a triple,
but I pretty much live on the middle chain ring and (occasionally) the
granny for extreme hills. In the 7 years since I've owned this
bulletproof bike I can count on two hands the times I've been in the 50
tooth outer chain ring.
QUESTION: Is it unheard of to swap that 50 (outer) with a 42 tooth chain
ring and make it a bit more of a useful crank set up (42/38)? It has
Tiagra drive train and the front Der looks as tho it'd handle it. it's a
110 BCD so I assume I could use any chain ring of that size?
Thanks ahead for any advice Mark E
--
Brad
Jul 29, 2012, 12:51:16 PM7/29/12
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Just out of curiosity, how many teeth in the various cogs of your rear cluster?
No reason not to make your front end fit what your actually pedaling gear wise.
There was a time when the smallest cog you could get in back on a freewheel was 14 and a 50 x 14 or 52 x14 or even 53 x 14 was not an unreasonable high gear.
But here is what happens when the rear shrinks.
52 x 14 yields a ratio of 3.71
50 x 14 yields a ratio of 3.57
Leave that 52 in place and go to an 11 tooth rear cog and you get a ratio of 4.72
To get that ratio with a 14 toothed cog, you would need a chainwheel of 66 teeth !
cf. http://farm4.static.flickr.com/3259/2727203279_1ba9ea700d.jpg
Brad in Watertown, NY where aging means riding with less teeth.
No reason not to make your front end fit what your actually pedaling gear wise.
There was a time when the smallest cog you could get in back on a freewheel was 14 and a 50 x 14 or 52 x14 or even 53 x 14 was not an unreasonable high gear.
But here is what happens when the rear shrinks.
52 x 14 yields a ratio of 3.71
50 x 14 yields a ratio of 3.57
Leave that 52 in place and go to an 11 tooth rear cog and you get a ratio of 4.72
To get that ratio with a 14 toothed cog, you would need a chainwheel of 66 teeth !
cf. http://farm4.static.flickr.com/3259/2727203279_1ba9ea700d.jpg
Brad in Watertown, NY where aging means riding with less teeth.
mstuartev
Jul 29, 2012, 2:13:18 PM7/29/12
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The Cassette is 11-32
Almost too big but I can get the changer to fit under it... and the extra low gears are helpful
In regards to what you are describing below... my issue is not having a high enough gear but not NEEDING a gear that high and needing more LOW gears (hence the 42 vs 50 outer). I'm lucky if I can top out at 15-16 MPH on flats after a slight downhill grade. Avg. speed is more like 11-12. My small cogs and the large chain ring rarely get dirty.
Mark
Almost too big but I can get the changer to fit under it... and the extra low gears are helpful
In regards to what you are describing below... my issue is not having a high enough gear but not NEEDING a gear that high and needing more LOW gears (hence the 42 vs 50 outer). I'm lucky if I can top out at 15-16 MPH on flats after a slight downhill grade. Avg. speed is more like 11-12. My small cogs and the large chain ring rarely get dirty.
Mark
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Harold Bielstein
Jul 29, 2012, 3:06:04 PM7/29/12
to mstuartev, 65...@googlegroups.com
What you're contemplating is essentially half-step gearing with a 42x38 and an 11x32 9-speed cassette. Switching from the large chain ring to the small chain ring for any specific rear cog results in a 10% smaller gear (or a 10% increase in leg speed). You're still looking at 102 gear inches at the top of the range and only 31 gear inches at the bottom. Personnally, anything over 90 gear inches is overkill but if you need lower gears, see if a 34 tooth small chain ring would be better.
Hal Bielstein
hkbie...@rap.midco.net
hkbie...@rap.midco.net
Brad
Jul 30, 2012, 12:24:10 AM7/30/12
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You sound pretty normal to me. I would switch out to the 42. It is a shame you can't get lower than a 34, but it will shift really easily and you will find good ways to use all the combinations. Hal is right about the gear inches analysis. Another way of saying that 50 x 11 is silly. In olden times with a 14 tooth small cog in back, it would mean a 63 tooth chainwheel.
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pruckelshaus
Jul 30, 2012, 10:29:06 AM7/30/12
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I swapped the 50t on my SRAM Apex (compact) crank for a 46t for the exact same reason. My front derailleur actually gets used now. I'm running the 11-32 in the back.
On Sunday, July 29, 2012 11:25:13 AM UTC-4, mstuartev wrote:
No real problems running out of gear, but I'm not as fast as I used to be, so it's all good.
On Sunday, July 29, 2012 11:25:13 AM UTC-4, mstuartev wrote:
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