Help me get up hills!
- Thread starter simon flannery
- Start date
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Dogtrousers
Kilometre nibbler
You can obtain the ranges that the OP needs with a double. Putting on a triple would mean a new front mech, possibly a new shifter, and a new BB, so I think that would be a bit more hassle than necessary. I don't think an uber-granny for crawling up mountains fully loaded is called for so swapping the chainset for a different double would be the least invasive approach.
Although, @Simmer says he managed a 30T big sprocket on the same bike (but does it have the same rear mech?)
cyberknight
As long as I breathe, I attack.
- Location
- Land of confusion
If that specs quoted are right they have upped the lower chain ring form a 38 to a 42 , without measuring the BCD
http://www.sheldonbrown.com/gloss_bo-z.html
it would be hard to say if its a compact or not, i would hedge my bets on not in which case you would need a new chainset and bottom bracket to change to a compact .Short term it would be cheaper and quicker to change the cassette to something with a wider range.
52/42 chain rings are fairly rare on new bikes as most have either a racing double 53/39 or compact 50/34 , i remember having a bike 20+ years ago with 52/42 and a 13-18 freewheel , now that was tough on hills
http://www.sheldonbrown.com/gloss_bo-z.html
it would be hard to say if its a compact or not, i would hedge my bets on not in which case you would need a new chainset and bottom bracket to change to a compact .Short term it would be cheaper and quicker to change the cassette to something with a wider range.
52/42 chain rings are fairly rare on new bikes as most have either a racing double 53/39 or compact 50/34 , i remember having a bike 20+ years ago with 52/42 and a 13-18 freewheel , now that was tough on hills
cyberknight
As long as I breathe, I attack.
- Location
- Land of confusion
pasted from a post by @RecordAceFromNew
"If your chainset is the same as the current Allez 16 then it would be a 52/39. That combined with the 2300 rear mech's spec you have an official wrap range available at the back of 35-(52-39), which is 22.
What that means, is assuming there is enough clearance between the mech's upper jockey wheel and the cassette, the widest range cassette you can theoretically have is 11T to (11+22) or 33T.
However the 2300 rear mech's official maximum sprocket size is 26T - but that figure is nearly always a pessimistic guide, while in reality it is dependent on frame/mech hanger geometry as well as the rear mech's parallelogram dimension - fortunately you can find out what the largest rear cog your existing set up can* handle by just a ruler - the number of teeth you can add to the 25 currently is the clearance between the 25 and the upper jocket wheel (when the chain is on the 25) in mm divided by 2. If e.g. the distance is 10mm then the largest rear cog your system can handle is 30T, but 29T will probably be best to allow for measurement error and a bit of wriggle room for the chain etc.
8 speed Shimano compatible cassettes are widely available - since you can pick any Shimano or Sram 8 speed cassette, whether "for" mtb or road. In fact since you are looking for low gears, Shimano or Sram mtb cassettes will offer a wider choice, e.g. all Shimano and Sram 8 speed cassettes on this page within the right tooth range are eligible.
Unless close ratio is important to you, if I were you I would pick one that starts from 11T (since wrap capacity is not going to be the limiting factor for the rear mech, and it will help speeding you downhill), and go up to near the maximum sprocket size limit by measurement as described above - that will give you the biggest range for the biggest hill most economically.
Regarding chain, if the existing chain is optimal in length then for every 4T increase in max rear cog size you should increase the new chain's length by 2 links above the existing. But if I were you I would not assume the existing length is right and just work out the optimal new length using a chain length calculator.
* if you wish the clearance can be maximised, allowing a bigger cog, by adjusting the mech's B screw."
What expert advice did Halfords give you?
Where are you and what type of hills are you having problems with? Could it be down to personal fitness, power to weight etc.
As many will know although not high the Lincolnshire Wolds have some steepish lumpy bits in, I ride a 42x23 bottom gear a lot on them.
Where are you and what type of hills are you having problems with? Could it be down to personal fitness, power to weight etc.
As many will know although not high the Lincolnshire Wolds have some steepish lumpy bits in, I ride a 42x23 bottom gear a lot on them.
cyberknight
As long as I breathe, I attack.
- Location
- Land of confusion
Ouch!!
Rob3rt
Man or Moose!
- Location
- Manchester
Intelligence happened!
Too right!!
Dogtrousers
Kilometre nibbler
Or get off and Push push push.
You could do that. Depending on your fitness and willpower
Kestevan
Last of the Summer Winos
- Location
- Holmfirth.
If you're planning on keeping the bike I'd suggest replacing the crankset with something a little bit more knee friendly
http://www.chainreactioncycles.com/shimano-claris-2450-octalink-compact-crankset/rp-prod109701
It's an Octalink crank, so you'd need a new bottom bracket too.
TBH when you've factored in the cost of the bits, and the labour to change it over (assuming you're not comfortable wielding the spanners yourself) you are rapidly approaching the point where it makes more sense to ebay the bike and buy something a bit nicer, you could probably get most of the way to the very good value Felt Wiggle are currently doing.......
http://www.wiggle.co.uk/felt-f95-sora-wiggle-exclusive/
http://www.chainreactioncycles.com/shimano-claris-2450-octalink-compact-crankset/rp-prod109701
It's an Octalink crank, so you'd need a new bottom bracket too.
TBH when you've factored in the cost of the bits, and the labour to change it over (assuming you're not comfortable wielding the spanners yourself) you are rapidly approaching the point where it makes more sense to ebay the bike and buy something a bit nicer, you could probably get most of the way to the very good value Felt Wiggle are currently doing.......
http://www.wiggle.co.uk/felt-f95-sora-wiggle-exclusive/
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