Author Topic: Gear Chainring  (Read 6287 times)

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Offline PeteJack

Re: Gear Chainring
« Reply #15 on: May 09, 2011, 12:59:15 am »
Be careful. If you have too big a difference between the big ring and the granny; if the chain is short enough for the granny gear it may be too short for the big ring. If you see what I mean. I

Offline mcparsons

Re: Gear Chainring
« Reply #16 on: May 09, 2011, 09:50:17 am »
I'm a huge fan of 22-32-44 front and 11-34 rear. Makes life so much easier.
...

I have no idea why these gears aren't available as stock on at least a few bikes in the U.S. They would meet the needs of most ordinary people riding between 4 and 27 mph.

Spot on.  I never regret having a 19" gear now and never used the 130" high gear that came stock.  The 22-32-44 crank set also means I use more of my gear combinations and all of my rear cogs which should extend their life.  I do occasionally drop the chain when shifting from the middle to lower chainring under pressure but I've learned to ease up when shifting. 

Offline RussSeaton

Re: Gear Chainring
« Reply #17 on: May 09, 2011, 01:59:56 pm »
Be careful. If you have too big a difference between the big ring and the granny; if the chain is short enough for the granny gear it may be too short for the big ring. If you see what I mean. I

Not sure how this problem would ever occur if you size the chain correctly.  Wrap the chain around the big ring and big cog and through the rear derailleur.  Just long enough to make this circle with a tiny tiny amound of extra play.  Then the chain is the right length.  If you are in the small chainring and small cog, the rear derailleur may not have enough length to take up all of the slack.  No problem.  Having the chain hang loose on the bottom does not cause any concern.  And using the small chainring and smallest 1-2-3 cogs is not something you should ever do anyway.

Offline whittierider

Re: Gear Chainring
« Reply #18 on: May 09, 2011, 02:29:48 pm »
Quote
Not sure how this problem would ever occur if you size the chain correctly.  Wrap the chain around the big ring and big cog and through the rear derailleur.  Just long enough to make this circle with a tiny tiny amound of extra play.  Then the chain is the right length.  If you are in the small chainring and small cog, the rear derailleur may not have enough length to take up all of the slack.  No problem.  Having the chain hang loose on the bottom does not cause any concern.  And using the small chainring and smallest 1-2-3 cogs is not something you should ever do anyway.
In the small-small combination, the chaing may rub on itself behind the upper derailleur pulley, which can't be good.  But our tandem has 24-42-52 with a 13-34 cassette and it works fine because the smallest ring only gets used with the cogs on the large half of the cassette.

Offline Tourista829

Re: Gear Chainring
« Reply #19 on: May 09, 2011, 08:33:36 pm »
Whitterider, I don't know, maybe I am old and decrepped but I had a 26, 44, 50 on my Cannondale for years. I always felt the 44" in the middle was a bit too high. I now have a Raceface crank, on my Comotion and I think it is a 24, 34, 46 and for me, it is so much easier to pedal. I still get in a solid 75 miles and occassionally 100 in a day. I feel so much better, at the end of the day. 

Offline PeteJack

Re: Gear Chainring
« Reply #20 on: May 13, 2011, 09:12:07 pm »
Quote
Having the chain hang loose on the bottom does not cause any concern.

You are probably right, although you can get the chain rubbing on itself as someone noted. Someone mentioned how loose my chain appeared to be when I was using the small ring so I took a link out. Now I can't use the big big combination because the chain's too short. I know you aren't supposed to use this combination either but I find you are much more likely to do this by accident (like when you turn a corner and find a surprise hill) than use the small-small combination by accident. I'll fix it next time I change the chain. FWIW Here's Sheldon on chain length http://sheldonbrown.com/derailer-adjustment.html#chain

Offline mu2flyer

Re: Gear Chainring
« Reply #21 on: May 15, 2011, 11:42:44 am »
I have a Co-Motion Mocha Tandem with 26” wheels. How does this effect gearing? Assuming the same gear combination how would it differ from a 700 wheel while climbing up hill? BTW mine has 52-39-30 front and 11-28 rear.

Offline PeteJack

Re: Gear Chainring
« Reply #22 on: May 15, 2011, 02:42:43 pm »
I can't get into gear inches and all that. They never mean anything to me. Here's my thought: on my Trek520 I have 51-38-24 and 11-32. My big front ring, about the same as yours, is comfortable on the flat. I used to have a 28 granny but I found it too big for loaded climbing so I swapped it for a 24 the smallest my derailer would take. It's not often you need it but when you do it's much appreciated. I suggest you try a smaller granny if your big ring is OK on the flat. It will be ludicrous on the flat or even slight gradients, the old pedaling air syndrome, but when you need it you'll both be so grateful it's there. It can be the difference between riding and pushing.

Offline RussSeaton

Re: Gear Chainring
« Reply #23 on: May 15, 2011, 03:30:13 pm »
I have a Co-Motion Mocha Tandem with 26” wheels. How does this effect gearing? Assuming the same gear combination how would it differ from a 700 wheel while climbing up hill? BTW mine has 52-39-30 front and 11-28 rear.

Smaller wheels make the gears easier.  Circumference of the tire.  So with a 26" wheel, the 30x28 low gear will be a little bit easier than a 700C wheel with 30x28.  Small amount easier.  10% easier between 26"x1.0" tire and 700Cx23mm wheel.  Diameter is roughly 24" for the 26" tire and 26.3" diameter for the 700C wheel.  At the high end, the 52x11, the 10% difference would be noticable.  At the low end, the 30x28, the difference may not be noticable.  At the low end you are talking 2 gear inch difference.  That is not much at all.  At the high end the difference is 10 gear inches.  Noticable.

Offline whittierider

Re: Gear Chainring
« Reply #24 on: May 15, 2011, 03:42:25 pm »
Quote
I have a Co-Motion Mocha Tandem with 26” wheels.  How does this effect gearing?  Assuming the same gear combination how would it differ from a 700 wheel while climbing up hill? BTW mine has 52-39-30 front and 11-28 rear.
Co-Motion's site says that bike comes with Continental Sport Contact 26x1.6" tires, so I went to Continental's website to see just what that is, and there's no such thing.  Guessing it's a mountain-bike 26 though, meaning 559mm bead seat diameter as opposed to 571 which is the road 26" (650c), I can guess the difference is a little under 5% (when you consider that the bigger tire partly makes up for the smaller rim diameter), meaning that a 23-tooth cog on yours would be approximately like a 24-tooth on a bike with 700c, and 700c with a 23-tooth would give a gear that's just a hair higher.  A cog of that size generally has you in the climbing area, so the difference between 23 and 24 teeth there would not be enough to feel.

Offline PeteJack

Re: Gear Chainring
« Reply #25 on: May 15, 2011, 03:57:57 pm »
I can only go by personal experience: if you are interested in getting up steep hills without walking get a small granny. It's not like it would cost you an arm and a leg to try one out which beats theorizing about gear inches, mine cost $25. Just ask your LBS if the ring you want to try will work with your derailer. Now if you have to use a different derailer...