Changing Rear Cassettes (Shimano 9 sp)

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Changing Rear Cassettes (Shimano 9 sp)

Postby MichaelB » Wed May 16, 2007 10:37 am

Dear all resident experts,

The question relates to a road bike with 50/39 Front Chainrings and 26-12 9sp rear Cassette

In my recent cycling efforts, on the flats I have ha\d to move from using the small chainring and 7th/8th gears on teh rear to the Large chainring due to my increase in average speed.

The initial thoughts were to get a seperate rear wheel and fit it with a 11-21 rear cassette, and use t for the flats, and keep the 26-12 for the hilly rides (still need it for sure).

To save the added expense of another rear wheel, how hard/messy/painful is it to change the rear cassette (& chain to match different length required) rather than just a rear wheel.

Or is there a third option (another bike is not an option) ?

What do others do ?

Cheers

Michael B
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by BNA » Wed May 16, 2007 10:47 am

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Postby europa » Wed May 16, 2007 10:47 am

Pah, I'd buy another bike and be done with it - 'clinical death' is diagnosed by the absence of the desire for a new bike.

Just ride the one your on as it is mate. What's wrong with riding on the large ring in the top gears all the time? Nothing unless you're trying to do it along the expressway. Unless you are running out of gears, don't touch your gearing, you don't need to. If you are running out of gears, it's not hard to address that (I just fitted a smaller granny for that very reason, but I realise you're looking at the other end of the cluster).

Now, once you take up racing, you may find you want a cluster designed more for racing - it used to be higher geared with smaller steps between the gears (and utter pain for your legs). I don't know if that still applies - probably does but to a lesser extent thanks to the number of cogs we carry on the back now. The thing is, once you take up racing, you may well find yourself buying a set of racing wheels - lighter, faster, different gears, and saving your existing set of wheels for the rigors of training.

When you wear out this set of gears (not long at the way you're going), think about where the holes are in your setup and fix them then.

Richard
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Postby rdp_au » Wed May 16, 2007 11:19 am

Now, once you take up racing, you may find you want a cluster designed more for racing - it used to be higher geared with smaller steps between the gears (and utter pain for your legs). I don't know if that still applies - probably does but to a lesser extent thanks to the number of cogs we carry on the back now.


Ain't that the truth. My old triathlon bike still hangs in the garage. Early 80's vintage, fitted with high range kit for the time - six speed, 13-18 rear cluster and 53-39 chainrings. Took it out for a ride a couple of months ago. It still felt fast, but bl**dy hell, going up any sort of incline was hard work!!

Cheers,

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Postby MichaelB » Wed May 16, 2007 11:28 am

Sage advice.

Funnily enough there is a set of Shimano WH-7700 wheels, 180km old with a couple of minor scratches (look like from hanging up on a rack) for $350 (no postage as they are in Adelaide ) but no rear cassette.

Also comes with a wheel bag !!!!

Mind you, haven't done any racing yet !!!

Can I resist .......................................................
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Postby europa » Wed May 16, 2007 12:16 pm

MichaelB wrote:Can I resist .......................................................


You're normal, of course you can't :D

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Gear Changing Technique

Postby rdp_au » Wed May 16, 2007 12:27 pm

Further to MichaelB's comments below, I'd be interested in techniques people use in changing gears. The approach I have always used is to try to use all gears available, but avoid the combinations that result in a heavily crossed chain. This means I would never routinely ride on the small chainring and top or near top gear on the cluster. Similarly, I'd not use the combination of large chainring, bottom gear on the cluster.

I have a triple crank and normally start on the middle chainring and middle of the cluster (or lower, depending on how steep the road is where Im starting). I then work up to the top third of the cluster (3rd or 4th on my 7 speed), probably 5th or 6th on a 9 speed, and then move across the the large chainring. If the road is flat, I continue changing up, moving all the way up to top gear. On an incline, change down on the cluster as needed until into the bottom third, and then move back to the middle chainring. If the hill is really steep, same process onto the smallest chainring.

This seems to give me the best spread of gear ratios, keeps changes clean, and minimises wear. What do you all do?

David
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Postby MichaelB » Wed May 16, 2007 12:42 pm

David,

Basically the same here. I occaisonally use the top two cogs with the small chainring, but not with any effort (diownhill to keep cadence right) rather than change up to the big ring for a short time.

Europa,

It's bloody hard, but I think I will, as the budget doesn't allow it this month. :cry:

Besides, I haven't even done any racing yet ...... :roll:
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Postby mikesbytes » Wed May 16, 2007 1:12 pm

Piece of cake to change the rear cassette.

Why don't you go for 11-26 so you have a full range.

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Postby europa » Wed May 16, 2007 1:26 pm

No, a full range is 11-32 like I've got :twisted:

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Postby MichaelB » Wed May 16, 2007 1:36 pm

mikesbytes wrote:Piece of cake to change the rear cassette.



Define "piece of cake" a bit further please.

Is it 10 min or 30 min + special tools ?
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Postby europa » Wed May 16, 2007 1:50 pm

MichaelB wrote:
mikesbytes wrote:Piece of cake to change the rear cassette.



Define "piece of cake" a bit further please.

Is it 10 min or 30 min + special tools ?


Don't forget swearing time and breakage :roll:

Here's Sheldon Brown's take on the process - http://sheldonbrown.com/k7.html

It is fairly simple, but you will need a couple of special tools. Then again, you'll need them anyway to replace worn cassettes so that's not a real problem - you're just buying them before you wear out your first cassette. I'm guessing it'd get old really quickly and that a second rear wheel would be the easy route ... actually no, the easy route is not to do it at all :wink:

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Postby Bnej » Wed May 16, 2007 2:51 pm

europa wrote:No, a full range is 11-32 like I've got :twisted:


I think there is such a thing as an 11-34.

Then you have to get a 22t granny and combine it with a SRAM dual drive hub, I think you could get a sub-10" low gear, and still get a very high top gear.
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Postby MichaelB » Wed May 16, 2007 3:36 pm

I guess what I was after was closer gearing for the flat rides, and then still retaining the flexibility for hilly rides.

It is not something that I'll be changing on a daily basis nor getting that much faster, hence the idea of a 11-21 or 11-23 for flat use, whilst keeping the 12-26 for hills (mainly use the 26 or 23 teeth gears).

The current spread on the 12-26 (S-RAM by the way) is 12-13-14-15-17-19-21-23-26.

Might just have to put up with what I have unless someone wants to donate a spare rear wheel ...... :wink:
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Postby europa » Wed May 16, 2007 3:43 pm

You can't get much closer than a one tooth spacing - they don't come in half teeth that I'm aware of. It's only on the larger cogs that the spacing jumps and if you're using them, you aren't on the flats. Sure you need a change?

My cluster is an S-RAM too - they aren't owned by Trek by anychance are they? Like Bongtrager - says so on the box of bar tape I bought recently
though it does explain why Trek dealers stock so much Bongtrager stuff.
:wink:

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Postby MAD GREEK » Wed May 16, 2007 3:59 pm

SRAM Corporation is a privately held bicycle component manufacturer based in Chicago, Illinois, founded in 1987. The correct pronunciation of SRAM is sram, as indicated on their website FAQ. SRAM is an acronym comprising the names of its founders, Scott, Ray, and Sam, where Ray is the middle name of company head Stan Day.
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Re: Changing Rear Cassettes (Shimano 9 sp)

Postby LuckyPierre » Wed May 16, 2007 6:27 pm

MichaelB wrote: ... the question relates to a road bike with 50/39 front chainrings and 26-12 9sp rear cassette ... how hard/messy/painful is it to change the rear cassette (& chain to match different length required) ... or is there a third option (another bike is not an option) ?

There is third option - get a 53 tooth large chain ring. The girlie bike has 53/39 chain-rings and a 12-27 cassette and I only run out of top gear when I'm doing over 55 km/hr (I don't have cadence sensors, so I don't know how fast my poor little legs are going to do that).
If you've got a compact crank, then it probably isn't a very palatable option, so you'll probably prefer an 11-xx cassette.
ps. most of the guys in the club with compact cranks run 11-23 or 11-21 casstettes and 50 / 36 chainrings (so there's a fourth option that covers both top an bottom gears). :)
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Postby mikesbytes » Wed May 16, 2007 10:38 pm

Jump to the Sheldonbrown web site and have a play with the gearing calculator.

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Postby MichaelB » Thu May 17, 2007 8:33 am

Thanks for the input guys.

Re the cranks, whilst I have a 50 tooth big ring, I still have a 39 tooth small ring, so a bit of a hybrid.

I don't have an issue with running out of gears on the big chain-ring (except downhill), but the aim will be to get a closer spread between the gears for the mainly flat rides that I do.

Funnily enough, the last time I was looking at chnaging a rear cassette on my bike, I ended up spending $1,350 on a new bike ......

On the wheels that were mentioned before (Shimano WH-7700). They are about 7 years old, have done 2 1/2 triathalons, and had the cassette changed once. The store strctched them when they did this in Canberra. The guy is selling them as his bike is now Camag equipped.

If they don't sell, may try a cash offer after ....

I am trying to resist .....

Edit :

Just read the initial review in Cycling News, and decided that I'll save my money ...

Shimano has had a rather uncharacteristically bumpy ride on its journey into the high-end pre-built wheelset market. Its first Dura-Ace model (WH-7700) definitely took the road less traveled, with an unusual, but visually striking, "lateral crossover" lacing pattern where the spokes crisscrossed each other over the centerline of the wheel on their way to being anchored into the opposite side of the rim. Some said it was high-tech; others found it just plain goofy. While Shimano claimed it made for a stiffer and lighter wheel, the sad reality was that they were heavy, unreliable, and difficult to true.

Q.E.D.
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