Gearing question

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F70100
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Gearing question

Postby F70100 » 4 Dec 2013, 10:49am

Hi folks.

New bike customer here looking for a day bike/ b&b-tourer and am being steered (by my very helpful local bike shop) towards a bike built around a Kinesis T2 frame with triple 50/39/30 and 12-30 cassette.

Having checked out the touring top tips sticky thread and Sheldon Browns gear calculator, I don't know if I should be concerned that the lowest ratio available will be 26". I note that tourers such as Galaxies sport a low ratio of 22". Some touring advice seems to suggest that something in the high teens might be beneficial (if not now, then at least eventually).

Should I try to find a chain ring for my build with 48/36/26 (as per Galaxies). This combo doesn't seem to be available on the usual components suppliers websites (Ribble, Parker Int etc).

Bike crew will be 53 year old male, 1.72m x 85kgs, average fitness and no experience.

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meic
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Location: Caerfyrddin (Carmarthen)

Re: Gearing question

Postby meic » 4 Dec 2013, 11:06am

My solution (and the cheapest solution short of "manning up") is to fit a smaller granny ring.

ie replace the 30t ring on the chainset with a 28, 26 or 24tooth inner ring.

24 is as small as you can go on that sort of crankset.

http://www.spacycles.co.uk/products.php ... b0s149p244

other sources and brands are available.
Yma o Hyd

tatanab
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Re: Gearing question

Postby tatanab » 4 Dec 2013, 11:09am

Depends on where you live, where you intend to B&B tour - Alps are obviously different to Holland. Unless there is something odd about the chainset you can always fit a smaller inner ring later. 30 by 30 is about a 27" gear. I cycle camp with an all up weight of 65 lbs and have a bottom gear of 24 by 28 i.e about 23" which is not greatly smaller. On a triple, I have 48/36/24 and rear 14-28. The chainset is easy to assemble with 5 arm MTB cranks or those available from SPA with TA rings.

Answer those first questions for yourself - where do I live, where do I want to go - and I think you might stick with what is on offer until you have a few miles under your belt.

freeflow
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Re: Gearing question

Postby freeflow » 4 Dec 2013, 11:15am

Just ask the shop to ensure that the triple chain ring has a 74 mm BCD for the 30 tooth chain ring. This will allow you to change the 30 tooth chainring down to a 22/24 tooth if you need to later on. I have this setup with my Ultegra kit (using 6603 chainset) and it works fine with a 24 tooth chainring. 30% hill are no problem (but that's just normal riding not loaded touring).

If the bike is assembled for you around a the TK2 from then you shouold ask the shop to fit a touring chainset from the off.

If it has to be shimano then you need either 105 5703 or Ultegra 6603. Ultegra 6703 restrixcts the smallest chainring to 30 tooth.

Ayesha
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Re: Gearing question

Postby Ayesha » 4 Dec 2013, 11:25am

If the bike is being built up custom, a 34 ( or 36 ) sprocket on the cassette will give you even more with a smaller inner ring.
Last edited by Ayesha on 4 Dec 2013, 11:29am, edited 1 time in total.

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cycleruk
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Re: Gearing question

Postby cycleruk » 4 Dec 2013, 11:28am

As been said above - A lot depends on what kind of cycling you would like to do.
I have the exact same gearing on one of my bikes and it covers most of what I do on good day rides.
My light tourer has 48/36/26 with 12/30 to give about a 23" gear, but I would look to go a little lower with a full load.
You can certainly have smaller chainset rings and a larger rear sprockets but these would have to be chosen with regard to the rest of the drive train.

Do you have a preference for the bike set-up?
(ie. Campagnolo/Shimano. drop bars or straight - gear changers etc.)
There's no such thing as a tailwind.
It's either a headwind, or you're going well.

Ayesha
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Re: Gearing question

Postby Ayesha » 4 Dec 2013, 11:47am

A 1:1 ratio is just over 3 mph at 40 rpm.

3.2 mph is 1.43 m/s.
Up a 20% hill this is a 0.29 metre rise per second.

Multiply the entire vehicle weight by 9.81 and multiply by 0.29 which will tell you how many Watts you will need.

For me, its 250 Watts ( 90kg ) and just about manageable for ten minutes or so. But then I’m knackered like after a 5 mile TT.

I reduced the ratio which allowed me a slower climb with a reasonable cadence.

Mark1978
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Re: Gearing question

Postby Mark1978 » 4 Dec 2013, 11:52am

30/30 is a pretty low gear which you can use to spin up all but the steepest hills - if you're carrying load it makes a difference of course.

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meic
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Location: Caerfyrddin (Carmarthen)

Re: Gearing question

Postby meic » 4 Dec 2013, 11:57am

I cant (or I have all of the steepest hills out to find me).

My bikes are all fitted with something like 24f 28r*, 26f 30r or 26f 32r.
Going any lower than that generally means that gearing is no longer my limiting factor and I can no longer control the bike on the climb.

* 26" wheels
Yma o Hyd

jb
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Re: Gearing question

Postby jb » 4 Dec 2013, 12:15pm

Pushing a bike with loaded panniers up a hill is more energy sapping than riding & very awkward so its best to have a low enough gear. Much below 22" though, and the feel becomes a little mushy, keeping a slow moving bike upright can be more energy consuming than pushing a higher gear. For super low gears its best to concentrate on a smooth pedal action at the top and bottom of the stroke rather than pushing at the power point causing a jerky action (but its still better than walking).

A small chainring below 24 teeth will wear out fairly quick unless you get a steel one so its best to get a bigger back sproket on the casset if you can.

I like to have at least a 23" gear when touring, even if I don't use it it's nice to know it’s there, just in case. Fatigue and the bonks can be cruel taskmasters at the end of the day.
Cheers
J Bro

F70100
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Re: Gearing question

Postby F70100 » 4 Dec 2013, 12:48pm

I live in Suffolk. There are hills, some steep, but I don't think I would classify them as long (will stand corrected).

Planned tours would be UK tourist stuff (C2C, Way of the Roses etc). If these leave me wanting more a further "investment" may be required... I feel i might be at the top of a very slippery slope!

In the short term, I'll see what my dealer can come up with that is within the budget (I do like the look of the T2). I guess like everyone else, I'm trying to avoid a costly mistake by getting it right first time but without having any personal experience to base a decision on, (I don't know if I want a relaxed/racy riding style, how quickly my fitness might improve, what sort of trips I will actually do, etc) you have to start somewhere by just taking a punt with a best guess.

One thing I do know is that this is a great resource - I've just joined CTC!

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meic
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Re: Gearing question

Postby meic » 4 Dec 2013, 12:52pm

If the bike has a triple chainset (and isnt one of the new expensive ones without a 74mm BCD inner ring fitting) and can take a 30t rear cassette then you can not go far wrong.

Exchanging the inner ring for a 24t version (at a cost of around £7) will give a very low bottom gear if the existing one is too high.
Yma o Hyd

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horizon
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Re: Gearing question

Postby horizon » 4 Dec 2013, 12:54pm

F70100 wrote:Hi folks.

New bike customer here looking for a day bike/ b&b-tourer and am being steered (by my very helpful local bike shop) towards a bike built around a Kinesis T2 frame with triple 50/39/30 and 12-30 cassette.



F70100: I get the uncomfortable feeling that you shouldn't even be looking at what a Galaxy has. The T2 AIUI is a winter trainer, i.e. really a road bike with some respect to practicalities. That will give you a good day rider but if you are partly hankering after a tourer then you might just end up with a string of "The Galaxy has this, can I have it on the T2?" questions. For many people I would presume this bike will be an excellent light tourer but they may be making a different set of compromises. The fact that the gearing has already given you food for thought means that you might not have fully explored the options before deciding on this bike and, I have to say, it might have been in the best interests of the bike shop to steer you away from doing so. I hope not.
Let's just get Brexit done so that we can get on with the important job of re-joining the EU!

Valbrona
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Re: Gearing question

Postby Valbrona » 4 Dec 2013, 1:25pm

F70100 wrote:Bike crew will be 53 year old male, 1.72m x 85kgs, average fitness and no experience.


That puts you in the 26/36/46 or thereabouts category. Not (currently) achievable with modern-style integrated axle chainsets. You need a square taper bottom bracket and something like a Stronglight Impact Triple chainset, which is 74/110 BCD, as opposed to the more common 74/130 BCD.

Gearing isn't just about getting a small enough inner ring, but also about having one or two other chainrings which might actually be useful. 50-something tooth chainrings on recreational bikes is not very clever.
I should coco.

mercalia
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Re: Gearing question

Postby mercalia » 4 Dec 2013, 1:32pm

I have a 26/36/46 with 30-11 at rear. Like you not young any more and I find that this set up works well, I rarely use the 46, spend most time on the 36. When I was 10 years younger I would regard this as rather slow ( now 61 ) but the puff not there any more. I get off and walk at steep hills. It maybe be mechanically true that pushing a laden bike up a hill less efficient than riding, but u cant really keep stopping if riding?
Last edited by mercalia on 4 Dec 2013, 1:43pm, edited 2 times in total.