Author Topic: CHAIN RING QUESTION  (Read 4907 times)

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Offline HONDO

CHAIN RING QUESTION
« on: October 18, 2006, 06:21:17 am »
I need a big drop in gearing on my touring bike without putting major money in it. Its set up with 52/42/30 and 11/32 cassette in the back.My LOB has a 24 inner chainring with a chain watcher he would put on it.He said that should work, just be careful dropping into the 24 . Low enough? I ride mountain roads in West Virginia and I dont have young legs.


Offline Badger

CHAIN RING QUESTION
« Reply #1 on: October 18, 2006, 09:26:51 am »
I had a similar set up and was able to drop all three chain rings from 52/42/30 to 48/39/24 with out replacing the crank set. It seems to works well with me towing a BOB.  I found the 24t worked well while I was riding near Mt. Shasta Ca. altitude above 5200 ft.  


Offline RussellSeaton

CHAIN RING QUESTION
« Reply #2 on: October 18, 2006, 10:13:54 am »
What your LBS says about replacing just the inner ring with a 24 tooth and putting on a chain watching device is good.  Sounds like you have a competent LBS.  $10 for the 24 tooth inner ring with a 74mm bcd and $10 for the chain watching device as nice insurance.  Do it.

Whether 24x32 is low enough?  I used that as my low gear loaded (40+ pounds of baggage) in the Alps and Dolomites and other unknown but just as steep or steeper climbs.  I was in my early 20s.  I weaved back and forth on several of the climbs.  I would have liked lower gears.  But in the US, there are very, very, very few roads as steep as you will find regularly in Europe.

And the steep sections on most roads, Europe or US, are short.  You can walk the few hundreds of yards and then start riding again on the less steep sections.  Takes some effort to get clipped in and going again.  Not many roads are 20+% grade for 2 miles straight.  They vary in grade a lot and go from short or very short really steep 16-22% sections to miles of 7-12% grade.  Walk the short really steep sections and ride the rest.

If you are using 9 speed, you can get a cassette with a 34 big cog cheap enough.  Your rear derailleur may or may not clear it depending on whether your frame's rear derailleur hanger is positioned just right.  Only way to tell is to try it.  A 34 will be a bit lower, maybe enough lower to matter, maybe not.

Otherwise, the only way to get lower gears is to change cranksets.  Mountain bike cranksets come from the factory with 22 inner chainrings.  If they are 5 arm sort of rare today, then they will have a 54 or 56 or 58 mm bcd, whatever the standard today is, and will accept a 20 tooth inner ring.  Maybe enough lower than 22 to matter, or not.

Or you can always devise a method to fit smaller wheels to your bike.  Smaller wheels result in lower gears suign the same chainrings and cogs.  Of course this is easier said than done.

And there are internal geared bottom brackets and rear hubs to get lower low gears too.  Don't know much about these things except they do exist.  Some you can combine with chainrings and cassettes.  Others are single chainrings and rear cogs like Rohloff.  But I'm assuming you are most interested in getting lower low gears working with what you already have.


Offline bicyclerider

CHAIN RING QUESTION
« Reply #3 on: October 23, 2006, 03:25:48 pm »
I'm riding the southern tier next spring and purchased a 2007 trek 520 with the stock 52/42/30
I noticed a reply from badger about switching over to
48/39/24 . Could you possible tell me the location to purchase those gears? The local bicycle shops are mostly into tri and road riders and townie bikes.
I saw the reply also about the chain watcher and wanted to locate a online store to purchase it also.
I changed to rear cassette to a 12/34

Jean Andre Vallery
www.bicyclejournals.net
Sarasota Florida
Jean Andre Vallery
Jacumba, California

Offline RussellSeaton

CHAIN RING QUESTION
« Reply #4 on: October 24, 2006, 07:02:35 am »
You bought a 2007 $1300 Trek 520 touring bike and now want to spend $100 to change chainrings for no benefit?  I'm a big fan of chainrings with pins and ramps to help upshifting.  So your replacement rings should have these pins and ramps on the middle and outer chainrings to be equal to the factory rings on the Trek 520.  Apples to apples comparison.  TA makes very nice chainrings in all sizes.  Peter White Cycles, Harris Cyclery, Vecchios in Boulder all sell them.  You are looking for 130mm bolt circle diameter.  The 24 inner ring can be as cheap as possible.  Nashbar sells a 24 tooth for $12 before sales.  24 tooth is 74 mm bolt circle diameter.  Expect to pay about $50+ for the nice TA middle and outer rings.  Each.  Shimano also sells 39 tooth middle rings for replacement on its newer 10 speed triples that come with 53-39-30 from the factory.  10 speed or 9 speed makes no difference.  Any bike shop could get you the 39 replacement triple middle ring.  About $50+.

Chain watchers can be found about anywhere.  Colorado Cyclist and Excel sell them.  Do a Google search on Third Eye Chain Watcher.  N'Gear Jump Stop.  Deda Dog Fang.  These are the name brand ones.  $10 each.

Why don't you just get the 24 tooth inner chainring and chainwatcher for about $25 total and be done with it.  52-42 rings are wonderful rings.  Far, far more useful than those silly 39 rings.  My bikes do not have goofy 39 rings in case you were wondering.  If the 52x12 gear is too high, don't use it.  Sadly Shimano and the other mountain bike component makers do not make cassettes that start with 13 cogs and go to 34.

If having 52 and 42 rings bothers you so much, then spend the money on getting a whole new crankset and bottom bracket than individual rings.  You will be the same cost except have even lower gears.  Mountain bike crankset with 44-32-22 rings and your 12-34 cassette will get you lower gears.  Same cost for a new crank and bottom bracket.  And then sell your current Trek 520 crank and bottom bracket and recoup some money.  Your bar end shifting on the Trek 520 will handle the front derailleur shifting just fine.


Offline bicyclerider

CHAIN RING QUESTION
« Reply #5 on: October 24, 2006, 07:38:47 am »
thank you for the comments.
I wasn't aware of the 6 to 8 k in elevation prior to getting the bicycle. but bottom line is "I can" pedal those gears 52/42 but wanted some advice and I got what I asked for and more. Another life lesson "ask for it and get it"
Last time across doing this southern tier solo in june through july  1999 I didn't go the ac route because of a wildfire was blanketing the region along the ac route in arizona. I stayed on the 10.

Jean Andre Vallery
www.bicyclejournals.net
Sarasota Florida
Jean Andre Vallery
Jacumba, California

Offline ptaylor

CHAIN RING QUESTION
« Reply #6 on: October 24, 2006, 04:23:27 pm »
Russel is far beyond me, but I agree that the Trek 520 (out of the box) does not have low enough gears. I wish Trek would clean up their act.

Paul
Paul

Offline driftlessregion

CHAIN RING QUESTION
« Reply #7 on: October 24, 2006, 07:52:48 pm »
A 24 tooth is fine but two cautions. First make sure the chainwatcher is adjusted correctly. It's a pain if the chain gets sucked UNDER the chainwatcher. A drop from a 42 to a 24 is a long way so shift carefully even with the chainwatcher. Slow your cadence slightly and let the chain drop onto the 24 chainwheel before increasing pressure. It works best with bar end shifters because you have more control but is doable with STI if you're careful. A 24/32 is a great low. I would have had to swap out my 105 rear for a Deore der to accomodate a 32 instead of my 27 cog and I didn't want to do that. If your rear der can handle the 32 cog go to http://sheldonbrown.com/harris/parts.html and get a 12-32 cassette or better yet a 13-34 or 14-34 and dump the useless 11 tooth cog. Good luck!


Offline biker_james

CHAIN RING QUESTION
« Reply #8 on: October 25, 2006, 06:01:31 am »
I had swapped the rings on my Cannondale T800 from the stocvk 52/42/30 to what you are considering-48/39/24, on both my bike, and my wife's. The 48 rings I paid $10- each for-clearance at Nashbar (they were even Cannondale branded), and about the same for the other rings. Not pinned and ramped, but they still shift fine.
I have since switched the crankset to a "treking" crank from Nashbar for about $50-. It comes with a 48/38/28, and then I spent a couple dollars and put on a 22 inner. Not sure if I've ever used my lowest gear (22/32), but I like to know its there.
Its probably cheaper to get hold of a trekking crankset and new bottom bracket (if necessary), than it is to search out ramped and pinned rings to replace all three rings. *Shimano Deore cranset with 48/36/26 is currently $69.99 at Nashbar**
My wife is still using her pieced together 48/39/24, and has no problems with shifting, or anything else about it. We have never used chain watchers, but I have considered them on occasion.
We toured with the stock gearing for a couple of years, but felt that we would prefer to have some lower gears, and have not regretted it. Cannondale has since changed their cranks to a 48/38/28 for the touring bikes I believe. I find the 38 and 48 are a lot more usable when the bike is loaded. Maybe its just me, but the 52 big ring is pretty useless on a touring bike, unless its a big downhill.

This message was edited by biker_james on 10-25-06 @ 5:03 AM

Offline RussellSeaton

CHAIN RING QUESTION
« Reply #9 on: October 25, 2006, 10:58:51 am »
"I have since switched the crankset to a "treking" crank from Nashbar for about $50-. It comes with a 48/38/28, and then I spent a couple dollars and put on a 22 inner. Not sure if I've ever used my lowest gear (22/32), but I like to know its there."

http://www.nashbar.com/profile.cfm?category=81&subcategory=1034&brand=&sku=11462&storetype=&estoreid=&pagename=Shop%20by%20Subcat%3A%20Road%20Cranks

The Nashbar Trekking crankset uses 110mm bcd rings for the outer and middle.  And 74mm bcd for the inner.  24 tooth is the smallest you can fit on the inner ring of the Nashbar Trekking crankset.  Same small ring you can fit onto the Shimano triple crankset that comes stock on the Trek 520.  You do not have a 22 tooth inner ring on the Nashbar Trekking crankset.

52x12=115"  48x11=116"  A 48 tooth chainring with an 11 tooth cog is actually a higher gear than a 52 with a 12 tooth cog.  Instead of wasting money changing chainrings, get a 12-34 cassette instead of 11-32 or even 11-34.  The gearing on the 12-34 cassette is better in my opinion.

I have a bike with a 52 outer chainring and another with a 48 tooth outer chainring.  Both have the exact same high gear.  Gearing is a combination of the front ring AND the back cog size.  In most cases its much cheaper and easier to change the back cassette.  Someone else mentioned Harris Cyclery selling 13-34 or 14-34 custom cassettes.  These are very easy and cheap to do yourself.  No need to pay someone else.  Just buy a couple 9 speed loose cog cassettes from Nashbar and make your own.

$20 for a 14-25 9 speed cassette.  14-15-16-17-18-19-21-23-25 cogs.
http://www.nashbar.com/profile.cfm?category=87&subcategory=1109&brand=&sku=15505&storetype=&estoreid=&pagename=Shop%20by%20Subcat%3A%20Freewheels

$20 for a 11-34 9 speed cassette.  11-13-15-17-20-23-26-30-34 cogs.
http://www.nashbar.com/profile.cfm?category=87&subcategory=1109&brand=&sku=13458&storetype=&estoreid=&pagename=Shop%20by%20Subcat%3A%20Freewheels

Take the 14-15-16-17 cogs from the first cassette and add the 20-23-26-30-34 from the second cassette and you have a very useful cassette for loaded touring with a 52-42-24 crankset.  Or take the 14-15-16-18 combined with the 20-23-26-30-34 if you like.

52x14=98"  Nice high gear.  48x11=116"  Way too high.  48x12=106"  Still too high for loaded touring.  48x13=98"  Nice high gear.


Offline biker_james

CHAIN RING QUESTION
« Reply #10 on: October 26, 2006, 06:02:57 am »
Well, I'll have to run out and double check the granny ring. Could be my memory has failed me there.
Switching to the 48 not only affects your very top gear (48/11-as mentioned higher than 52/12, but lower than the 52/11 it came with) but makes the other cogs more usable. When I replace my cassette I may go to a 12/34, but maybe not, for the times I ride the bike unladen, and feel like screaming downhill. Your suggestion does get him lower gearing with the granny ring, but I think a lot of us would like to use more than our smallest chainring, and switching to the 38/48 makes those rings usable all around-I go to the granny ring much less often because the middle ring will get me up the smaller hills. I guess it depends what works for your riding style and strengths.
I will say thanks for pointing out how cheap cassettes are available thru Nashbar now- although I'd prefer a SRAM cassette, the Shimano might do at that price.