Gearing enquiry

[Benjahmin]

Just bought a 46t chainring to replace a 44t on the wifes Big Bear. To maintain/improve hill climbing I've found a 12/32 cassette to replace the existing 15/28.
In all my years I've never changed the gearing on a bike. So, can anyone have a guess at if there's enough movement in the derailleur to take the extra size on both cogs? Here's a picture of the derailleur in first gear with the current set up.
Thanks.

 

[Woosh]

Hello Benjahmin,

The Big Bear is fitted with Shimano TZ21 freewheel, 7-speed, 14T-28T
https://www.sigmasports.com/item/Shimano/TZ21-Freewheel-7-speed-14-28-Cassette/JWE

If you need higher gear inches, Sunrace make one that goes 13T-34T
https://www.evanscycles.com/sunrace-index-7-speed-freewheel-00102413

 

[Nealh]

In general if the number of gears are the same then yes.
You may have to adjust the cable tension in top and bottom gear though you are loosing and gaining rear ring sizes so might all pan out equal. Other wise end stops might need playing with.

You will have to add a link or two to the chain length, for correct chain length place chain on front and rear largest gear only (not around the derailleur) mark the taut chain where it meets and add 1 link.

 

[Deleted member 4366]

You should get a DNP freewheel with 11T top gear, like 11T/30T. The cassette you got probably won't fit. Is it a free-hub or free-wheel?

 

[Woosh]

Is it a free-hub or free-wheel?

it's a freewheel.

 

[flecc]

Yes you are ok. Shimano's Tourney rear mechanism that you have is a megarange one that can cope with sprockets up to 34 teeth.
.

 

[Deleted member 4366]

it's a freewheel.

I was asking about the 12/32 replacement one.

 

[Benjahmin]

Don't know d8veh, I've been zooming all over the web and I've lost the link. However the one woosh has linked looks fine. So I'll go for that and order a slightly longer chain as well, then I can knock out as many links as I need to.
Thanks for the help guys.

 

[Benjahmin]

So, turns out that the Sunrace 13-34 is a megarange. I've got one of these on another bike and the ten tooth jump between 1st and 2nd is brutal. Leaves you spinning out in 1st but 2nd is too heavy. Seems like all the closer ratio are 11-28. There are DNP11-32 ones that have a 8 tooth 1st to 2nd jump, so sort of megarange. There are some DNP 11-30 freewheels which would be ace. Trouble is they all seem to be sold out. Anyone know of one going?

 

[flecc]

How about this 13 to 28 if you change back to your 44 tooth chainring to keep the former hill climbing while raising the top gear?
.

 

[Benjahmin]

Thanks Flecc.
This is turning into a right pain. The 46t crankset is on its way, this would give a higher top gear with the existing 14-28. Job done -I thought. However SWMBO informed me, over the weekend, that she is also struggling on some of the hills hereabouts. News to me as she's usually in front. That's why I'm trying to change that bottom ratioThe annoying thing is the DNP 11-30 seems readily available from America, yet rarely offered in this country.
Are we a GEAREST nation one wonders?

 

[anotherkiwi]

Thanks Flecc.
This is turning into a right pain. The 46t crankset is on its way, this would give a higher top gear with the existing 14-28. Job done -I thought. However SWMBO informed me, over the weekend, that she is also struggling on some of the hills hereabouts. News to me as she's usually in front. That's why I'm trying to change that bottom ratioThe annoying thing is the DNP 11-30 seems readily available from America, yet rarely offered in this country.
Are we a GEAREST nation one wonders?

The americans don't have any trouble importing cheap Chinese bikes with freewheels not cassettes...

I ordered mine direct from DNP and the postage was bad but not too bad. They even built me a special cassette to my specifications, one off job!

A 46:14 top is actually slower than 38:11 and a 38:32 is lower geared than 46:28... I would have gone for a 38 tooth front and a DNP 11-32 on the back for leisure cycling and a lovely Hebie CHAINGLIDER 359.

 

[Benjahmin]

Thanks AK, think I follow what you're saying.
Well I've just found this:
https://www.spacycles.co.uk/m2b0s112p3087/IRD-7-Speed-Classica-Freewheel
Not entirely sure it's a screw on. Can anyone confirm.
At the price it should jump up and screw itself on

 

[anotherkiwi]

Yep them be freewheels. I think I paid less than that for a DNP 11-32 a custom made cassette and postage from Taiwan

 

[anotherkiwi]

Sunrace make a lovely 11-36 10 speed freewheel with 2-3-4 spacing as you go down the gears. Unfortunately the stack height makes it impossible to fit in anything but a 145mm dropout.

 

[Deleted member 4366]

There are some DNP 11-30 freewheels which would be ace. Trouble is they all seem to be sold out. Anyone know of one going?

I have loads of 8 speed 11T/32T. They have 28T second gear, so not such a jump. £20 including postage.

 

[Benjahmin]

Thanks D8veh, but the Big Bear's a 7 speed.

 

[flecc]

Thanks AK, think I follow what you're saying.
Well I've just found this:
https://www.spacycles.co.uk/m2b0s112p3087/IRD-7-Speed-Classica-Freewheel
Not entirely sure it's a screw on. Can anyone confirm.
At the price it should jump up and screw itself on

Yes, a freewheel, but the 13 - 32 does have some megarange jump.

Your rear mechanism will work with it ok though.
.

 

[Benjahmin]

Thanks Flecc. According to the spec the ratios are 13-15-18-21-24-28-32, so there's a 4 tooth jump for the bottom two gears, nothing like the 10 tooth jump on my other bike. If nothing else turns up I think this will do.
Mr wallet's going to moan though.

 

[flecc]

Indeed, that jump isn't severe and might not be too noticeable. It looked larger in the photo of the sets.
.