New cog for Dawes Giro 300

[Racer_Rob]

I've got a Dawes Giro 300 (as you might have guessed) but want a smaller cog on the cassette (11T really). At the moment I have a Shimano HG37 7 speed 13-28T.

Is this the right thing http://www.bonthronebikes.co.uk/424-416152
(If not could someone point me in the right direction either in that site ^^ or www.wiggle.co.uk)

Can I then take off the cassette lockring then remove the 2nd largest cog, move the other cogs up and have the new 11T as the smallest. I guess the length of the chain won't have to be altered?

Thanks for the help, ask for anymore info!

 

[alfeng]

I've got a Dawes Giro 300 (as you might have guessed) but want a smaller cog on the cassette (11T really). At the moment I have a Shimano HG37 7 speed 13-28T.

Is this the right thing http://www.bonthronebikes.co.uk/424-416152
(If not could someone point me in the right direction either in that site ^^ or www.wiggle.co.uk)

Can I then take off the cassette lockring then remove the 2nd largest cog, move the other cogs up and have the new 11T as the smallest. I guess the length of the chain won't have to be altered?

Thanks for the help, ask for anymore info!

FWIW. Yes, you can theoretically do what you are suggesting EXCEPT you cannot use the current 13t cog you have since the last cog has "stops" which keep it from sliding all the way onto the freehub; so, you would probably need at least two new cogs.

AND, while it's not for me to tell you how to spend your money OR how much to spend on a component, I think that £9.19 + shipping for the single cog is probably the least efficient way to spend your money.

If your rear wheel's freehub really has a lockring [NB. the oldest 7-speed freehubs used a threaded, last cog to secure the stack], then I would suggest that you buy an 8-speed MTB cassette & simply eliminate one cog-and-spacer BECAUSE most of the MTB cassettes come with an 11t smallest cog -- the 8-speed cog spacing is essentially the same as the 7-speed cog spacing.

Most of the SRAM 8-speed cassettes use separate cogs, so if you get an 11-28, you can simply use it as an 11-24(?) or any other combintion you want. The 8-speed SRAM may cost more (but, possibly less if you can find one on eBay.UK), but you'll probably have a slighltly better cog combination -- possibly, something like 11-12-14-16-18-20-24-28 as the initial stack ...

If you want to keep the 28t OR even have a larger rear cog in addition to the 11t, then you can simply get a cassette with the wider range because I found that you can have as much as an 8t difference (maybe, more?) without any shifting problems (presuming everything is properly adjusted!).

To over simplify the possibilities, any of the separate cogs from your current cassette EXCEPT FOR the 13t can be stacked with the cogs from an 8-speed cassette if the 8-speed cassette uses separate cogs.

You will not need to alter the length of your chain.

 

[Racer_Rob]

I agree I did think £9.99 was a bit steep!

I had a quick look at MTB cassettes, I'd guess something like this would be OK http://www.bonthronebikes.co.uk/322-417889
It may work out cheaper to get some over priced cogs instead of a totally new cassette though, would the new 11T have to be a special type to have the stops on it, or do you think the one on the link I posted before would have stops already (seems as your not going to go smaller than that!)
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The other little problem I've come across is removing the current cassette which I've attatched some pictures of. I guess I need a special tool to remove the lockring? I've showed the tool I have at the moment but won't that remove the whole hub and not allow me to get to the cogs.

 

[alfeng]

I agree I did think £9.99 was a bit steep!

I had a quick look at MTB cassettes, I'd guess something like this would be OK http://www.bonthronebikes.co.uk/322-417889
It may work out cheaper to get some over priced cogs instead of a totally new cassette though, would the new 11T have to be a special type to have the stops on it, or do you think the one on the link I posted before would have stops already (seems as your not going to go smaller than that!)
---
The other little problem I've come across is removing the current cassette which I've attatched some pictures of. I guess I need a special tool to remove the lockring? I've showed the tool I have at the moment but won't that remove the whole hub and not allow me to get to the cogs.

FIRST, if you were to buy a Shimano cassette, you would want an LX-or-lesser cassette because the largest 5 (?) cogs on the XT & XTR cassettes are attached to a spider ... whereas the LX-and-lesser cassettes are comprised of separate cogs.

The issue, for the moment, is moot because your rear wheel has a FREEWHEEL ... and, after you remove it, you can only replace it with another Freewheel ... from single-speed (e.g., BMX) to multi-speed (what is currently attached).

Generally, a 13t cog is the smallest that is available for a Freewheel.

If you REALLY want to use an 11t cog, then you have to relace the rim on a new hub -- the Shimano ACERA hub should be suitable -- or, buy a new wheel.

You are in a situation where you have to decide how much money you want to spend ...

Perhaps, the LEAST EXPENSIVE option for you would be to change the chainring ...

46t is the largest that I am aware of for micro-/(94BCD 5-arm) cranks.

48t is the largest for standard 4-arm/(104BCD) that won't cost an arm-and-a-leg -- Shimano has a 48t in either steel or alloy. ZIPP now has a 53t(?) chainring in the 104BCD size, but I reckon it will cost more than £45, possibly much more!

If your crank has a 5-arm, 110BCD crank, then you can probably put a 52t chainring on it without making any other changes other than adjusting the height of the front derailleur ... but, in some cases you might have to change the BB spindle to a longer one to allow the larger chainring to clear the chainstay ...

BTW. Removing Freewheels usually requires a lot of leverage ... it is easier (?) to put the tool in a BENCH VISE, set the wheel on the tool, and then turn the wheel counter-clockwise. I've had Freewheels which could only be remove by destroying them (i.e., grinding them off ... and, using the HEAT of the process to expand the Freewheel's body enough & 'melt' the grease to make using a large pipewrench barely suitable).

 

[Racer_Rob]

I've already got a 52t chainring, I had looked into getting a larger one before but prices go waaay up.

I'm not really a fan of getting a whole new hub, I was only thinking of this being a small upgrade!

Do you have any links to a 11t cog with stops which would be suitable for a freewheel? (and I guess a 13t aswell which doesn't have the stops on it as I guess I can't use the current one with stops anywhere except at the end).

In terms of removing the cassette, won't the tool I attatched in the pic remove the whole cassette? Don't you need a seperate tool for taking off the brass-coloured lockring?

Thanks for all the help.

 

[alfeng]

I've already got a 52t chainring, I had looked into getting a larger one before but prices go waaay up.

I'm not really a fan of getting a whole new hub, I was only thinking of this being a small upgrade!

Do you have any links to a 11t cog with stops which would be suitable for a freewheel? (and I guess a 13t aswell which doesn't have the stops on it as I guess I can't use the current one with stops anywhere except at the end).

In terms of removing the cassette, won't the tool I attatched in the pic remove the whole cassette? Don't you need a seperate tool for taking off the brass-coloured lockring?

Thanks for all the help.

First, your rear wheel does NOT have a cassette ... it has a FREEWHEEL -- a Freewheel incorporates BOTH the cogs & ratcheting mechansim.

http://sheldonbrown.com/k7.html​

FWIW. 99% of the information that Sheldon Brown (RIP) provides is accurate ... the 1% that is "wrong" will involve things that are so arcane that it probably won't have any impact you.

The tool you have is designed to remove the entire Freewheel.

While I know of & know some people have changed the cogs on a Freewheel, I think you have to be very motivated (more than I have ever been).

http://sheldonbrown.com/gearing/index.html​

Shimano makes a special hub (it must have been designed in the late 80s ... HARRIS CYCLERY carries it) which can accept a Freewheel which has smaller cogs, but the cost is probably more than the cost of most Freehubs (the ratcheting mechansim is a part of the hub) which you can commonly find ...

A Shimano ACERA rear hub (for example) will probably cost only a little over £10 if you can find one on eBay.UK ... and, probably about £15 from your LBS. The ACERA is designed for a 7spd cassette. (i.e., cogs, only -- no ratcheting mechanism). A Shimano LX hub will cost only a little more than an ACERA hub AND allow you to use anything from a 7-speed to a 10-speed cassette.

BTW. Are you saying that your crankset currently has a 52t chainring mounted on it?