Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Touring Have a dream to ride a bike across your state, across the country, or around the world? Self-contained or fully supported? Trade ideas, adventures, and more in our bicycle touring forum.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 03-26-12, 10:51 AM   #1
nondo
Junior Member
Thread Starter
 
Join Date: Mar 2012
Bikes:
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Gear ratio for touring with trailer

Hi there. I currently have a Decathlon's B'twin 7 (http://www.decathlon.co.uk/btwin-7-id_8076847.html). Chainrings are 48-38-28 and 7-speed cassette 14-28. I'm going to pull a heavily-fully-loaded BOB trailer for a couple of months, mostly on flat roads, but 20% in mountains.

I've been training but it turns out that pulling it on steep uphill with no sort of granny gear will not only force me to stop every 500m, but eventually injury me on the long run. So i'll consider changes, and as i'm totally newbie i'm asking for your help.

1 - Taking a look a Sheldon Browns gearing calculator, i could change the smaller chainring from 28 to 20. The lower gear would no longer be 28gi, to become 20gi... i think that would be enough for no-hurry-touring?!
Does it make sense? Would this be feasible? (I mean, compatibilities and other stuff i may be totally unaware)

2 - With the loaded bike i'll never use the higher gears. I know it would be wiser to upgrade the crankset, but wouldn't that be more expensive?

3 - Help me!


(Also, you're free to comment whether the bike is inappropriate for touring. It's just i'm on a budget and i'll rather spend it on the road, even if i go slower...).

Thanks in advance.
nondo is offline   Reply With Quote
Old 03-26-12, 11:07 AM   #2
chasm54
Banned.
 
Join Date: May 2010
Location: Uncertain
Bikes:
Posts: 8,657
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
You certainly want a low gear of no more than 20". My own gearing for touring goes down to 18", and while I very rarely need to go that low, it isn't unknown and I am not pulling a trailer. However, I'd question whether simply swapping out the 28 for a 20 is the way to go - the drop from the 38 to the 20 is colossal. Look at putting a bigger sprocket on the back.

Or, look at the bike. Any bike is appropriate for touring, as long as you are comfortable on it and can stay comfortable during long days in the saddle. BUt all that suspension is going to be very wasteful of energy, and really isn't any good to you if you are staying on roads or trails. It absorbs force that ought to be used in pushing you forward. I hear what you say about being on a budget, but a pre-owned touring bike might not be too expensive and if your tour is two months long, would be likely to make a massive contribution to your enjoyment.
chasm54 is offline   Reply With Quote
Old 03-26-12, 11:15 AM   #3
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 19,614
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 432 Post(s)
min gear of a 74 bcd chainring is 24t, can't be smaller than the bolt circle
that attaches it.
your crank has to have a 56 or 58 bcd granny gear mount for a 20t

Sram makes a cassette with a 34t or a 36t biggest cog, for the rear..
fietsbob is offline   Reply With Quote
Old 03-26-12, 03:51 PM   #4
nondo
Junior Member
Thread Starter
 
Join Date: Mar 2012
Bikes:
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thank you for your replies.

chasm54: The suspensions would be no problem, since they can be "turned off". I enjoy the bike, have done small tours (no longer than three days) and i feel comfortable with it. Also, i'm not so committed so seriously to long daily distances.

Buying a new bike is completely outside my plans, unless i have to spend more than half of the value of this one replacing gearing system. And i live in Portugal, where touring is not common, and used touring bikes are not be easy to find.

Still, i have some doubts on what you wrote. From the gearing calculator i see there would be a gap somewhere, but i would rather have it there than in low gears eheh

My last question to you would be: how much would cost the cheapest option of replacing gear, in your opinion? (Considering i would be satisfied with 18'' as lowest...)

fietsbob: sorry but i couldn't understand your reply, what's "bcd"?
nondo is offline   Reply With Quote
Old 03-26-12, 05:16 PM   #5
Bezalel
Senior Member
 
Join Date: Mar 2010
Location: City of Brotherly Love
Bikes: Raleigh Companion, Nashbar Touring, Novara DiVano, Trek FX 7.1, Giant Upland
Posts: 1,516
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
For a couple months tour, I'd suggest a rigid frame and fork. If you insist on using this bike, I'd suggest that you replace your crankset with a 22-32-44 chainring combination. Your current chainrings are likely to be riveted on so you may have to also replace the cranks.

BCD = Bolt Circle Diameter
Bezalel is offline   Reply With Quote
Old 03-26-12, 11:05 PM   #6
Doug64
Senior Member
 
Doug64's Avatar
 
Join Date: Mar 2009
Location: Oregon
Bikes:
Posts: 3,892
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 44 Post(s)
The bike will be OK, if you can figure out a way to come up with lower gears.

Suggestion: Think about a small chainring, if you have interchangeable rings, with 26 or 24 teeth. This will shift much better than trying to go to a 20 tooth low, which I don't think you can do anyway without changing cranksets. Most front derailleurs are at the edge of their range with a 12 tooth difference in ring size. Shifting up from a 20 to a 38 ring would probably not work.

Then change the rear cassette to a 14-34 which would also require a new rear derailleur. You might be able to do both things within 100 USD. This would give you low of 20.4 with a 26 and an 18.8 with the 24 tooth chainrings. From the information on the Decahtalon website it is not possible to tell what components the bike has or figure out options.

Portugal is a great place to cycle. We started a tour in Lisbon last summer and our route through Portugal took us through Evora, Beja, Serpa, and then into Spain. Good luck on you trip.
Doug64 is offline   Reply With Quote
Old 03-27-12, 11:27 AM   #7
AngrySaki
Socrates Johnson
 
AngrySaki's Avatar
 
Join Date: May 2007
Location: Waterloo, Ontario
Bikes:
Posts: 492
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I also think a new crankset is probably your best option.
I was able to get a 22-32-42 mountain bike crankset a couple of years ago for about $60USD that's held up fine (TruVativ Isoflow).
AngrySaki is offline   Reply With Quote
Old 03-27-12, 12:20 PM   #8
nondo
Junior Member
Thread Starter
 
Join Date: Mar 2012
Bikes:
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thank you for your feedback. Forgive my newbiness, and here it goes again:

Doug: from what i see in the sheldon brown calculator, a cassette for 14-34 needs to be 9-speed, correct? Is it because i need more speeds that i need to buy also new derailleur?

AngrySaki: I visited a store today, and a brand new cheap shimano 22-32-44 was exactly what the dude proposed me (he said 30). He said it should be enough, but i'm really carrying heavy load, tent, kitchen & food, and 22'' as lower might not be enough as chasm54 pointed.
Also, the guy said no ring could be changed alone: all the crankset needs to be replaced.

So, assuming that i would keep 7-speed in the back (mega-range freewheel 11-34), with a new 44-32-22 crank set i would have 18.1'' as granny and 25.7'' as a second gear and 26.4'' as the third. I know they're kind of spaced, but my point is to travel, even if i do it slowly (as i said, steep mountains are a fraction of the trip...) Does this sound stupid?
nondo is offline   Reply With Quote
Old 03-27-12, 02:06 PM   #9
bicyclridr4life
Bicyclerider4life
 
Join Date: Aug 2006
Location: Florida and Idaho
Bikes: Huffy Beach Cruisers, Miami Sun Trike, Vertical PK7, KHS Montana Summit, Giant Cypress DX, Schwinn OTC Stingray
Posts: 706
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
My bike came with a 48/38/28 crank and 14/28 six speed freewheel. I pull a trailer everywhere I go. I changed the crank to a 46/36/22 and upgraded the freewheel to a 14/34 seven speed.
__________________
"Whenever I see an adult riding a bicycle, I know there is hope for mankind." (H. G. Wells)

Last edited by bicyclridr4life; 03-27-12 at 02:11 PM.
bicyclridr4life is offline   Reply With Quote
Old 03-27-12, 02:09 PM   #10
bicyclridr4life
Bicyclerider4life
 
Join Date: Aug 2006
Location: Florida and Idaho
Bikes: Huffy Beach Cruisers, Miami Sun Trike, Vertical PK7, KHS Montana Summit, Giant Cypress DX, Schwinn OTC Stingray
Posts: 706
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by nondo View Post
Thank you for your feedback. Forgive my newbiness, and here it goes again:

Doug: from what i see in the sheldon brown calculator, a cassette for 14-34 needs to be 9-speed, correct?
No, it does not have to be a 9 speed. I just upgraded my bike to a seven speed SunRace 14/34 freewheel (was originally a 14/28 six speed)

Provided the crank rings are not welded together, or integral with the spider, you should be able to change them individually.
__________________
"Whenever I see an adult riding a bicycle, I know there is hope for mankind." (H. G. Wells)

Last edited by bicyclridr4life; 03-27-12 at 02:13 PM.
bicyclridr4life is offline   Reply With Quote
Old 03-27-12, 03:01 PM   #11
nondo
Junior Member
Thread Starter
 
Join Date: Mar 2012
Bikes:
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I suppose the crank rings are welded, because the dude said it wasn't possible to change only one ring, and i should buy another crankset. How could i confirm this by myself?

The rear deraileur is a Shimano Altus. How do i know if it is compatible with 14-34?

If it is possible to change only crankset + chain + 14/34 freewheel, i can get away with less than 100, and i think it's worth it!
nondo is offline   Reply With Quote
Old 03-27-12, 03:49 PM   #12
Doug64
Senior Member
 
Doug64's Avatar
 
Join Date: Mar 2009
Location: Oregon
Bikes:
Posts: 3,892
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 44 Post(s)
Quote:
So, assuming that i would keep 7-speed in the back (mega-range freewheel 11-34), with a new 44-32-22 crank set i would have 18.1'' as granny and 25.7'' as a second gear and 26.4'' as the third. I know they're kind of spaced, but my point is to travel, even if i do it slowly (as i said, steep mountains are a fraction of the trip...) Does this sound stupid?
This would work fine. the 44 tooth chainring /11 tooth rear cog will give you about 28mph at 90 RPM. The 22/34 low end will give you a pretty good granny gear.That is the same high end/ low end gear ratios I have on my touring bike.
Doug64 is offline   Reply With Quote
Old 03-27-12, 04:17 PM   #13
pacificcyclist
Senior Member
 
Join Date: Dec 2007
Location: Canada
Bikes: 2012 Masi Speciale CX : 2013 Ghost 29er EBS
Posts: 918
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
My ex-RIP 26" touring bike was a full suspension bike made by BMC. There are a lot of people who tour with suspension bikes no problem either with BOB or with touring racks either locally or globally. I even toured with a lady who had a $50 Canadian Tire (Crappy Tire in Canada) full suspension from Vancouver to the Queen Charlotte Islands with the same gears -- lots of walking for her and lots of waiting for me but she made it!

Yes, there is no problem with your bike. But I would make some modifications.

To get lower gears, just replace the whole crankset with an Alivio 42-32-22 mountain gear as I think your front derailleur can be lowered enough to accommodate a smaller 42 ring. The Alivio crank is heavy, chain rings are welded but is tough. It's cheap as well -- I paid like $30 US for it last time. I think your stock crankset (Altus?)also have welded chain rings. With the rear, you can replace it with a Shimano CS738 HG-50 7 speed 13-34 cassette. 22/34 should give you low gears to climb steep steep hills. Again, it's $30 for this in the USA/Canada. You can get the Shimano Altus to work with a 34 at the back, but it may grind a bit the last time I modified one bike. Since you won't be using 34 all the time, this should last a good while before the tour ends. As with anything, you need a new chain.


Hope this helps.

Last edited by pacificcyclist; 03-27-12 at 04:33 PM.
pacificcyclist is offline   Reply With Quote
Old 03-27-12, 04:37 PM   #14
Bezalel
Senior Member
 
Join Date: Mar 2010
Location: City of Brotherly Love
Bikes: Raleigh Companion, Nashbar Touring, Novara DiVano, Trek FX 7.1, Giant Upland
Posts: 1,516
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Quote:
Originally Posted by nondo View Post
The rear deraileur is a Shimano Altus. How do i know if it is compatible with 14-34?
http://techdocs.shimano.com/media/te...9830686243.pdf
Bezalel is offline   Reply With Quote
Old 03-27-12, 04:58 PM   #15
skilsaw
Senior Member
 
skilsaw's Avatar
 
Join Date: Jul 2010
Location: Victoria, Canada
Bikes: Cannondale t1, Koga-Miyata World Traveller
Posts: 1,546
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I put a 10 sp 11-34 on the back and 48-36-26 on the front of my first bike.
Pull a Burley Nomad on road tours.

My other bike has regular 9 sp MTB gearing.
Ride it loaded with panniers in off-road tours.

At times, I wish I had the MTB gearing on the first bike.
I have to walk it up long hills of 13% plus.
skilsaw is offline   Reply With Quote
Old 03-27-12, 09:17 PM   #16
Doug64
Senior Member
 
Doug64's Avatar
 
Join Date: Mar 2009
Location: Oregon
Bikes:
Posts: 3,892
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 44 Post(s)
nondo,

After pulling 50 lbs of groceries in my trailer up a steep little hill today in a 26-34 (lowest gear on my cyclocross bike), I really want to reinforce the idea of getting lower gears on your touring bike
Doug64 is offline   Reply With Quote
Old 03-27-12, 10:38 PM   #17
Northwestrider
Senior Member
 
Northwestrider's Avatar
 
Join Date: Apr 2006
Location: Gig Harbor, WA
Bikes: Surly Long Haul Trucker, Gary Fisher Hoo Koo E Koo, Dahon Mu P 24 , Bacchetta Strada, Rodriguez Tandem, Wheeler MTB
Posts: 2,453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Going with a 20t chain ring up front, I believe you'll find is very expensive. If you go with 22-32- 42 up front and a 36 cog in back on the cassette, I think you'll be fairly happy.
Northwestrider is offline   Reply With Quote
Old 03-28-12, 11:55 AM   #18
djb
Senior Member
 
Join Date: Jul 2010
Location: Montreal Canada
Bikes:
Posts: 5,757
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
I second the idea to put a mtn bike crankset on 42/32/22 or .44/32/22 and a rear cassette of at least 32 teeth. You should stay within your budget and the lower gearing really will make a difference for enjoying the trip and being easier on your knees.
Bon dia
djb is offline   Reply With Quote
Old 03-28-12, 12:28 PM   #19
indyfabz
Senior Member
 
Join Date: Jan 2010
Bikes:
Posts: 9,381
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 375 Post(s)
Quote:
Originally Posted by nondo View Post
I suppose the crank rings are welded, because the dude said it wasn't possible to change only one ring, and i should buy another crankset. How could i confirm this by myself?
By checking to see if there are bolts (usually hex bolts) that allow you to remove each chain ring from the crank.
indyfabz is offline   Reply With Quote
Old 03-28-12, 12:35 PM   #20
djb
Senior Member
 
Join Date: Jul 2010
Location: Montreal Canada
Bikes:
Posts: 5,757
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Remember though that an alvio mtnbike crankset at 30 euros, even if you can't change the rings, will.last year's and years and years. A single chainring can easily cost more. This crankset will be the most cost effective way for him to go.
djb is offline   Reply With Quote
Old 03-28-12, 02:28 PM   #21
nondo
Junior Member
Thread Starter
 
Join Date: Mar 2012
Bikes:
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
So, following your advice, i'll opt for a new 42/32/22 crankset, opting for a rear cassette of 11-34 (since i have to buy a new one, i'll play it safe with a 17.5 granny) and a new chain.

My last doubt is whether or not my Altus derraileur is compatible or not with the new setup. The datasheet http://techdocs.shimano.com/media/te...9830686243.pdf mentions capacity of 43T (?), largest sprocket 34T (ok), smallest sprocket 11T (ok) but says it is supposed to be used on 8 sprockets! (But heck, if it works on my current 7 gear setup...!)

Thanks so much for your help.
nondo is offline   Reply With Quote
Old 03-28-12, 02:54 PM   #22
pacificcyclist
Senior Member
 
Join Date: Dec 2007
Location: Canada
Bikes: 2012 Masi Speciale CX : 2013 Ghost 29er EBS
Posts: 918
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by nondo View Post
So, following your advice, i'll opt for a new 42/32/22 crankset, opting for a rear cassette of 11-34 (since i have to buy a new one, i'll play it safe with a 17.5 granny) and a new chain.

My last doubt is whether or not my Altus derraileur is compatible or not with the new setup. The datasheet http://techdocs.shimano.com/media/te...9830686243.pdf mentions capacity of 43T (?), largest sprocket 34T (ok), smallest sprocket 11T (ok) but says it is supposed to be used on 8 sprockets! (But heck, if it works on my current 7 gear setup...!)

Thanks so much for your help.
Yes, the Altus is compatible the last one I installed but that was on a 8 speed system. DO NOT CROSS SHIFT from big chain ring to big cassette ring (43T/34T) which is what the warning on the upper front chain ring rear cassette sizes. But since you have a 42T front, it's ok for a short period of time. A word of advice. When you are climbing steep hills, REMEMBER to shift your front derailleur to the front granny chain ring BEFORE you shift to the biggest cog (cassette ring) at the back. That way, you won't put a lot of stress on the poor derailleur. Good luck on your tour!

Last edited by pacificcyclist; 03-28-12 at 02:59 PM.
pacificcyclist is offline   Reply With Quote
Old 03-28-12, 05:09 PM   #23
Bezalel
Senior Member
 
Join Date: Mar 2010
Location: City of Brotherly Love
Bikes: Raleigh Companion, Nashbar Touring, Novara DiVano, Trek FX 7.1, Giant Upland
Posts: 1,516
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Quote:
Originally Posted by nondo View Post
So, following your advice, i'll opt for a new 42/32/22 crankset, opting for a rear cassette of 11-34 (since i have to buy a new one, i'll play it safe with a 17.5 granny) and a new chain.

My last doubt is whether or not my Altus derraileur is compatible or not with the new setup. The datasheet http://techdocs.shimano.com/media/te...9830686243.pdf mentions capacity of 43T (?), largest sprocket 34T (ok), smallest sprocket 11T (ok) but says it is supposed to be used on 8 sprockets! (But heck, if it works on my current 7 gear setup...!)

Thanks so much for your help.
Regarding changing your cassette, I think your bike uses a Freewheel and not a cassette. The way to check is by looking for a model number, if it starts with MF it's a freewheel if it starts with CS than it's a cassette.

Capacity is a simple concept. Any time you shift to a chainring or cog other than the largest ones, the derailleur cage needs to take up that much chain, so if you have a 22-44 crankset you need a capacity of 22 and for a 11-34 cassette you need a capacity of 23 which would require a total capacity of 45.

Derailleurs don't care how many speeds you have all indexing is done at the shifter, as long as the model number matches the datasheet you can ignore the speed spec and concentrate on the other specs.
Bezalel is offline   Reply With Quote
Old 03-28-12, 05:21 PM   #24
djb
Senior Member
 
Join Date: Jul 2010
Location: Montreal Canada
Bikes:
Posts: 5,757
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Quote:
Originally Posted by Bezalel View Post
Regarding changing your cassette, I think your bike uses a Freewheel and not a cassette. The way to check is by looking for a model number, if it starts with MF it's a freewheel if it starts with CS than it's a cassette.

Capacity is a simple concept. Any time you shift to a chainring or cog other than the largest ones, the derailleur cage needs to take up that much chain, so if you have a 22-44 crankset you need a capacity of 22 and for a 11-34 cassette you need a capacity of 23 which would require a total capacity of 45.

Derailleurs don't care how many speeds you have all indexing is done at the shifter, as long as the model number matches the datasheet you can ignore the speed spec and concentrate on the other specs.
good explaining.

his link to his bike seems to indicate that it uses a "7 speed cassette", funny that it would use 7 and not 8 speed stuff as the bike cant be that old, but if thats what it is, then thats what it is....
Ive seen 7 speed cassettes on sale at a store here in Montreal at reasonable prices, so they are around.
djb is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 01:21 AM.