Changing Gear Ratio

[st599_uk]

Hi

I recently had a bit of a life changing illness - I went from riding 100 miles a week to not being able to get to the end of the street. I'm back riding - although I've changed the type I'm doing. On a good day, I'm fine, on a bad day I'm struggling badly with hills. I'd really like to go touring next summer and the crankset, cassette and chains are starting to wear.

So, I'm thinking of trying to change the gearing a bit to give me a lower gear or two. I don't really use the big ring (of 3) on the crankset, so wouldn't really miss the top end speed, but I don't really know what I'm looking for

How do I know which crankset and cassette are suitable?

[reohn2]

This thread may be of some help :- viewtopic.php?f=5&t=125974

[gaz]

Welcome to the forum.

It would be useful to know more about your current set up.

What chainset are you using, BCD, number of teeth on chainrings, type of bottom bracket?

Freewheel or cassette, how many sprockets, smallest and largest?

Front and rear shifters, make and models?

[st599_uk]

Hi

Many thanks for the quick reply - the bike is a hybrid with the original drive train:

Shifters Shimano EZ Fire 51 21 speed
Front Derailleur Shimano M191
Rear Derailleur Shimano Altus
Cassette Shimano TZ31 14x34
Crankset SR Suntour XCC 28/38/48
Chain KMC Z51
Bottom Bracket Sealed Cartridge

I've replaced quite a lot of the bike (pedals, tyres, pannier rack etc.), but the drive chain just worked, so I left it.

The teeth are starting to round over, so need replacing anyway, so I thought I'd try and get the upgrade done at the same time.

[Brucey]

a chainset with smaller chainrings might be a good start, eg

https://www.ebay.co.uk/itm/SR-Suntour-XCT-MTB-Cranksets-175mm-cranks-22-32-42-rings-White-or-Black-MTB/283097804731

cheers

[reohn2]

a chainset with smaller chainrings might be a good start, eg

https://www.ebay.co.uk/itm/SR-Suntour-XCT-MTB-Cranksets-175mm-cranks-22-32-42-rings-White-or-Black-MTB/283097804731

cheers

I agree,that would be a simple and economic solution.

[Norman H]

Replacing the complete chainset, as suggested by Brucey, might well be cheaper than replacing all three individual rings, and would be the way to go if the old chainset is shot anyway. If the existing chainset is a 5 arm 110/74 BCD design, and the outer and middle rings are still serviceable, you could get away with just changing the inner ring. 24T is the smallest that you can fit on a 74BCD spider though.

The other problem that you might face if you intend loaded touring is the rear sprockets. The TZ31 is a screw on freewheel I believe. Freewheel style rear hubs have a reputation for bending and breaking rear axles. You might have to consider a wheel rebuild at some time to incorporate a cassette style rear hub.

[thelawnet]

It sounds like you are looking at:

* new freewheel (to replace old worn model) £15
* new chain (ditto) £5
* new crankset (as per brucey's suggestion) £25

Other possible upgrades:

* new wheel (to get rid of freewheel & strengthen) , e.g., https://www.ebay.co.uk/itm/Mavic-A119-R ... 3597372539 £60
* 9-speed shifter/brake lever unit £13 https://www.ebay.co.uk/itm/SHIMANO-ST-E ... 2154519709
* 11-36 9-speed cassette £15 (though you need a new freewheel which costs about the same anyway)

Note by this point (£100+) you could probably find a suitable used 27-speed mountain bike but of course no guarantee that would not need various maintenance items either.

[st599_uk]

Many thanks for all the great hints. Exactly what I joined Cycling UK for.

As I really like the geometry of the bike, it's really comfortable for me, and it can carry loads to form shops, sports clubs etc. I'm definitely going to replace the parts that are wearing down.

It's done quite a distance now (mainly before I was ill), so I'm going to hand it over to a mechanic to service and replace the parts. I think that I may go for both the upgrade to a 9 speed cassette/freewheel and the smaller chainset as (if my maths is correct) that gives me both the lower gears I want and a couple that are higher than I currently have - good for days when I'm good and bad.

[st599_uk]

Just an update, I've updated the rear wheel to a cassette and the crankset. Performs beautifully with a couple of more bits I'd like to change.

Took it out at the weekend, cruised up some hills with plenty left in the tank.

Thanks for all the help.

[foxyrider]

Nice to see some feedback

Enjoy your riding