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Old 07-18-11, 08:28 AM   #1
Desi
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New bie question ...Conversion - compact to triple.possible ?

I am newbie to road bikes ; I have trek fuel ex 8 (mountain bike)a
nd it has triple crank and overall mechanism helps me a lot duriing steep climbs.

I have new road bike with SRAM Rival group set with compact crank. Since my legs are not that strong; I struggle climbing hills on road bike hence I am wondering if I can make changes to the road bike to get that extra low gear (same as i have on trek fuel ex8) for steep climbs..

What parts and budget I should be looking for ?

I just wanted to get an idea before walk into the lbs..

Thank you all..

Last edited by Desi; 07-18-11 at 08:29 AM. Reason: Typo
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Old 07-18-11, 08:38 AM   #2
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Mountain Bikes and Road bike gearing has very little in common when it comes to making it easier to go up hill like you are asking, MTB's (Your Trek) have smaller (26" wheels) Front and rear suspension, and totally different angles (geometry) and a 22/32/42 crank, where your road bike will have sharper angles, no suspension and a 34/50 crank.

What cassette do you have? if a 11-23 then it will be hard to climb with, if a 12-32 it should be very easy. suggest looking at your cassette ratio before going to a triple, which would involve totally new groupset as SRAM doesn't do triples.

Rule #5 also applies here
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Old 07-18-11, 08:50 AM   #3
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Many cyclo-camping touring bike set-ups use a MTB compact triple,
44/32/22,
road triple will use 53/39/30 combinations,
"Trekking" type, is similar to what MTB's used in the recent past.
48/38/28..
The mix and match from competing companies will need sorting some..
SRAM-mano.
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Old 07-18-11, 08:57 AM   #4
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Many cyclo-camping touring bike set-ups use a MTB compact triple,
44/32/22,
road triple will use 53/39/30 combinations,
"Trekking" type, is similar to what MTB's used in the recent past.
48/38/28..
The mix and match from competing companies will need sorting some..
SRAM-mano.
Shimano has specific Touring versions of MTB components like the M771-k crank, which has a touring friendly 26/36/48, which is virtually the old standard drive, and there is also LX which is now a touring groupset.

SRAM as the 12-32 cassette which is why they haven't release a triple crank as this range covers what the triple did.
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Old 07-18-11, 09:31 AM   #5
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Desi, The rear cassette swap is the easiest and least expensive option, even if it requires a different rear derailleur. What is the range of your current cassette?

Brad
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Old 07-18-11, 09:36 AM   #6
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Easiest path is the cassette. I don't believe the SRAM front shifter can handle a triple, and the front derailleur cage shape is for the double.
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Old 07-18-11, 09:49 AM   #7
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all I know at this time the road bike has SRAm Rival group set; since i am work at present; will check cassette in the evening when i get home.

Thanks for your help...
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Old 07-18-11, 09:49 AM   #8
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Thank you all for looking into it...
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Old 07-18-11, 10:12 AM   #9
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Desi, The rear cassette swap is the easiest and least expensive option, even if it requires a different rear derailleur. What is the range of your current cassette?

Brad
Hello Brad,

What do I check to see what type of cassette & range it has ? Will it help I I post picture in the evening.... It is a newer bike ( 2010)..Thanks
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Old 07-18-11, 10:23 AM   #10
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Hello Brad,

What do I check to see what type of cassette & range it has ? Will it help I I post picture in the evening.... It is a newer bike ( 2010)..Thanks
If you give the forum the tooth count of the smallest and largest gear, for example 11-27, that should help us help you.

Brad

Last edited by bradtx; 07-18-11 at 10:24 AM. Reason: sp
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Old 07-18-11, 10:28 AM   #11
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Simply count the number of teeth on the smallest and largest cogs. You may see the number of teeth stamped in the metal as well. You could also post here what make and model of bike it is and we could look up the specifications assuming that it is stock.
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Old 07-18-11, 11:03 AM   #12
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Hello Brad,

What do I check to see what type of cassette & range it has ? Will it help I I post picture in the evening.... It is a newer bike ( 2010)..Thanks
SRAM Apex medium cage rear derailler: $65
SRAM Apex 11-32 cassette: $69
New 10-speed chain: $40-$70, depending on brand

You can use your current shifters without a problem. With the compact crank, you'll have a pretty low gear ration.

I just built up a bike with an Apex groupset, because I'm old and fat. ;-) I'm really pleased with it so far.
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Old 07-18-11, 01:28 PM   #13
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Desi, The rear cassette swap is the easiest and least expensive option, even if it requires a different rear derailleur. What is the range of your current cassette?

Brad
I did this recently. I got a MTB deore RD with an 11-36 Cassette. Inexpensive compared to a triple conversion and it is plenty low enough for hills even while towing my two kids in a trailer behind me(extra 70 lbs).
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Old 07-18-11, 01:44 PM   #14
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I did this recently. I got a MTB deore RD with an 11-36 Cassette. Inexpensive compared to a triple conversion and it is plenty low enough for hills even while towing my two kids in a trailer behind me(extra 70 lbs).
This is a good choice but you may need the Apex Derailure to handle the larger gears in the cassette
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Old 07-18-11, 01:47 PM   #15
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Quote:
Originally Posted by Desi View Post
I am newbie to road bikes ; I have trek fuel ex 8 (mountain bike)a
nd it has triple crank and overall mechanism helps me a lot duriing steep climbs.

I have new road bike with SRAM Rival group set with compact crank. Since my legs are not that strong; I struggle climbing hills on road bike hence I am wondering if I can make changes to the road bike to get that extra low gear (same as i have on trek fuel ex8) for steep climbs..

What parts and budget I should be looking for ?
Lenard Zinn claims success combining Campagnolo 10 speed shifters (Campagnolo Centaur) with SRAM rear derailleurs (Red) and a Shimano spaced casette.

All Campagnolo left shifters will run triple front derailleur; best would be a set of NOS 2010 Centaur 10 speed Ultrashift levers. Your LBS probably won't be able to get them (they're discontinued) but Shiny Bikes in the UK still has them for $200 (you don't pay VAT as a US resident).

Use a Campagnolo comp triple front derailleur so you don't run out of pull on the left lever (they went from having 12 clicks of which 7 were used for the triple to 6 of which all get used). About $50 from the UK. 50-100% more from your LBS.

Take your pick of triple front Cranksets. Shimano and Campagnolo shift better than FSA and may or may not cost more (Shimano nameless numbered parts are affordable) - the Campagnolo Comp Triple runs about $120 from the UK. Maybe double that from your LBS.

(UK online retail prices are lower than US wholesale).

You'll also need a longer chain if switch from a 50 big ring to a 53/53.
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Old 07-18-11, 01:49 PM   #16
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Originally Posted by slowandsteady View Post
I did this recently. I got a MTB deore RD with an 11-36 Cassette. Inexpensive compared to a triple conversion and it is plenty low enough for hills even while towing my two kids in a trailer behind me(extra 70 lbs).
Unfortunately the OP has SRAM road shifters so he's going to have to replace the derailler, cassette, and chain, so it's not going to be an inexpensive option.
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Old 07-18-11, 02:02 PM   #17
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Unfortunately the OP has SRAM road shifters so he's going to have to replace the derailler, cassette, and chain, so it's not going to be an inexpensive option.
SRAM has an Apex medium cage derailleur which will mate a 12-32 to a 50-34 compact crankset.

It lets them sell to the recreational market with only one more SKU to build, distributed, and stock compared to the triple approach requiring at least a couple more cranksets, one more front derailleur, and one more left shifter. It's nicer for OEM sales too, allowing bike companies to make fewer models that some people won't buy.

With

50-34 x 11-12-13-15-17-19-21-24-28-32

matching the range of

53-39-28 x 12-13-14-15-16-17-19-21-23-26

the SRAM wide-range double won't be as nice to ride hard on flatter terrain as a triple but will cost a lot less.

Last edited by Drew Eckhardt; 07-18-11 at 02:07 PM.
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Old 07-18-11, 02:09 PM   #18
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SRAM has an Apex medium cage derailleur which will mate a 12-32 to a 50-34 compact crankset.

It lets them sell to the recreational market with only one more SKU to build, distributed, and stock compared to the triple approach requiring at least a couple more cranksets, one more front derailleur, one more left shifter, and a lot more bikes which some people won't buy.

With

50-34 x 11-12-13-15-17-19-21-24-28-32

matching the range of

53-39-28 x 12-13-14-15-16-17-19-21-23-26

the SRAM wide-range double won't be as nice to ride hard on flatter terrain as a triple but will cost a lot less.
Yep, the mid-cassette gaps on my Apex cassette are less than ideal, but OTOH, Apex is really not intended for people who are going to be riding hard. If/when the OP feels less of a need to have bail-out gears, it's easy enough to swap the cassette back to his original and go from there.
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Old 07-19-11, 07:13 AM   #19
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If you give the forum the tooth count of the smallest and largest gear, for example 11-27, that should help us help you.

Brad
It is 11 - 26
Thanks
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Old 07-19-11, 09:52 AM   #20
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Crank - Compact to Triple = new crank + derailleur + shift lever
Gears - SRAM Rival - 11-32 tooth = new cassette
Gears - Road to MTB - w/ Shimano it's a 9-speed rear derailleur + 11-34 or 11-36 cassette (but I don't know SRAM)
--------
Small chainring on Compact = 34, on Triple = 30
So ratio w/ max SRAM cassette with compact = 1 revolution of wheel requires 0.94 (32/34) revolution of the pedals
....with triple = 1 revolution of wheel requires 1.07 (32/30) revolution of the pedals
More revolutions of the pedals per mile mean less effort (and slower speed).
That's 13% easier (I think I have that right)
Good luck

PS - Hills that kill you now will seem routine next year if you ride a lot.
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Old 07-19-11, 10:18 AM   #21
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Small chainring on Compact = 34, on Triple = 30
So ratio w/ max SRAM cassette with compact = 1 revolution of wheel requires 0.94 (32/34) revolution of the pedals
....with triple = 1 revolution of wheel requires 1.07 (32/30) revolution of the pedals
More revolutions of the pedals per mile mean less effort (and slower speed).
That's 13% easier (I think I have that right)
No.

Road triples have a 74mm BCD which will take a 24 ring. Although 53-39-24 (or even 50-39-24) exceeds the manufacturers' stated range on road front derailleurs plenty of people are satisfied with the performance, especially with a chain catcher. 46-36-24 would be in the capacity spec, shift a bit better, and still provide a big enough gear with an 11 or 12 starting cog.

Comparing non-stock chain rings in both cases, compact doubles have a 110mm BCD which will take a 33 ring.

24/33 = 27% easier if you really need it.

A 50.4 BCD randonneuring double (Grand Cru makes one with retro style and reasonable price tag) or 110/74 super compact (the inner two rings of a triple mounted on a slightly longer bottom bracket) with 46/30 rings is another option where a compact isn't enough.

Last edited by Drew Eckhardt; 07-19-11 at 12:32 PM.
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Old 07-19-11, 12:19 PM   #22
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It is 11 - 26
Thanks
Thanks. The 11-32 cassette will give you about 7-8 gear inches advantage (~18%), which should make a noticeable difference. More than likely you will have to change the rear derailleur to cope with the larger gear spread. At a bike shop the cost would be for the cassette, the RD, labor and should take about 30 minutes to complete. Keep your old parts.

Brad
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