vickster
Legendary Member
Phew!I have not heard from crank arm for a while
Who rides a standard crank?
- Thread starter Andywinds
- Start date
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OP
OP
Andywinds
Senior Member
I've had a look at what I am running and here are the results. Not sure what these ratios are good for, all I know is it's hard to climb.
Front =52/40
Back =23/12 - 8 speed.
Maybe something like this would offer me better range?
Chainring Size: 50 Tooth, 34 Tooth
Chain: shimano
Bottom Bracket: Shimano
Cassette: Shimano 11 speed
Cassette Range: 11-28 Tooth
Front =52/40
Back =23/12 - 8 speed.
Maybe something like this would offer me better range?
Chainring Size: 50 Tooth, 34 Tooth
Chain: shimano
Bottom Bracket: Shimano
Cassette: Shimano 11 speed
Cassette Range: 11-28 Tooth
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Winnershsaint
Guru
On the current bike I run a 50/34 compact with ten speed 12/27 out back, truth is I rarely use the 27 tooth gear at all, but it's nice to know it's there. On my new bike I had the choice of compact or pro compact and settled for the former with an 11/28 cassette mainly because the 11 tooth gives me a gear higher than I currently have whilst still retaining a bale out gear if need be. This is largely a decision made in deference to my knees, which I intend to keep into ripe old age.
Yellow Saddle
Guru
- Location
- Loch side.
Yes, it has been a while....last Thursday at 16:51 or some such.I have not heard from crank arm for a while
Hugh Manatee
Veteran
I have an older 130 BCD 600 tricolour crank on one of my bikes. I wanted lower gears for winter so I know 38/50 fits fine. The bike also has a braze on front mech attachment and on my frame, I didn't need to extend the slot to accept the smaller diameter ring. There was enough space as it was.
Poacher
Gravitationally challenged member
- Location
- Nottingham
Damn right it's hard to climb! I think in terms of gear inches - which has a pedigree going back to 'ordinaries' aka penny farthings - in which you travel forwards pi * number of inches, which was originally the diameter of the front wheel. Anyhow, I'd consider a gear of 40" suitable for most climbing (at my age and weight I'm now looking at 30" or so!). Your lowest gear, calculated as teeth on chainring * nominal diameter of wheel / number of teeth on rear sprocket, is 40 * 27 / 23 = 47 (rounded to nearest integer). By the same calculation, your top gear is 117", plenty high enough not to spin out in normal riding.
Your options are to fit a smaller chainring, fit a cassette with more teeth on the largest sprocket, or as you suggest, both.
Firstly, it may be possible to find a solution with your existing chainset; the obvious first suggestion would be a different cassette. Is it Campag, Shimano or something more exotic? Working on the assumption that it's Shimano, you could fit a straight 8-speed replacement HG50 13-26, to give a new low gear of 41.5.
Other options include 11-28, 11-30 and 11-32, BUT you'd probably never use the two smallest sprockets on these, and might well need a longer rear derailleur.
Next to consider is your chainset and what the bcd (bolt circle diameter) is. Measure (fairly accurately!) the distance between the centre of two adjoining bolts: if this is 76.4mm you have 130 bcd and can swap the 40 for a 38 tooth and a worthwhile reduction in bottom gear, if it's 79.4mm you have 135 bcd and could only reduce to a 39 tooth, scarcely worthwhile. Maybe time to think about a compact? Try the 13-26 cassette first, though.
Do you have a square taper bottom bracket? An "upgrade" to this month's latest flavour would require you to replace this with one which is likely to wear more quickly.
While I'm denigrating "upgrades", can I also suggest that an 11-speed cassette might not fit your hub? Nowt wrong with 8 speed!!!!!!
ChrisEyles
Guru
- Location
- Devon
Yep - 52/40 up front with 12-23 on the back is brutal! Swap it out for an 11-28 or even better 11-32 and you'll have a much easier time of it. There will be a bit of a bigger jump between gears on an 11-32 eight speed cassette, but it's not a problem for most riders. As for rarely using the smallest sprockets, this is true, but you won't half be glad of them when you do occasionally use them
Do check the capacity of your rear derailleur first though.
OP
OP
Andywinds
Senior Member
Thanks Chris and Poacher. Your help is really appreicated. I do like the idea of using an 8 speed 11-28 cassette and wouldn't the existing derailleur take this better? The hill I was climbing was only 1.2 miles but had 607ft elevation, I know this is not much but it killed me with an average speed of 5mph 
I will be looking for a second hand road bike in the next few weeks so will look out for something with a better gear range anyway. But may just get another cassette if I can get one cheap enough.
I will be looking for a second hand road bike in the next few weeks so will look out for something with a better gear range anyway. But may just get another cassette if I can get one cheap enough.
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ChrisEyles
Guru
- Location
- Devon
That's a tough hill - 9.6% average gradient over 1.2 miles - doing that in a 40/23 gear would kill me too!
What rear derailleur do you have? If you know the model it should be possible to find out the size of the largest sprocket you can have on the back (agreed that your existing one is unlikely to handle an 11-32, but you may get away with 11-28, still enough to make a good difference) e.g. I have a shimano acera derailleur which has a largest sprocket size from 28t - 34t, with a total capacity of 43t (capacity is the difference between your chainrings 52-40 = 10 plus the difference between your largest and smallest sprockets on the rear 28-11 = 17, so 27t for your proposed set-up).
You may also need a slightly longer chain if you have taken out the excess links on your current one, but if you're getting a new cassette it's not a bad idea to fit a new chain at the same time in any case.
What rear derailleur do you have? If you know the model it should be possible to find out the size of the largest sprocket you can have on the back (agreed that your existing one is unlikely to handle an 11-32, but you may get away with 11-28, still enough to make a good difference) e.g. I have a shimano acera derailleur which has a largest sprocket size from 28t - 34t, with a total capacity of 43t (capacity is the difference between your chainrings 52-40 = 10 plus the difference between your largest and smallest sprockets on the rear 28-11 = 17, so 27t for your proposed set-up).
You may also need a slightly longer chain if you have taken out the excess links on your current one, but if you're getting a new cassette it's not a bad idea to fit a new chain at the same time in any case.
OP
OP
Andywinds
Senior Member
It's a Shimano SORA. This bike is borrowed but the guy that owns it was given it and never rides the thing.
ChrisEyles
Guru
- Location
- Devon
Do you know which model it is? There are Sora 3500, Sora 3300 etc derailleurs, all with slightly different capacities/max sprocket sizes. If you don't know which it is, try google imaging "Sora rear derailleur" and click on some of the links which look the same as yours to find out the model and capacity/max sprocket size.
ChrisEyles
Guru
- Location
- Devon
Others may be able to confirm, but it looks to me like one of these, a Sora 3300:
http://sdeals.com/index.php/home/gears/rearmechs/product/13108-shimano-sora-rd-3300-rear-mech
If so, that gives a capacity of 29t and a maximum sprocket size of 27t (though you *may* be able to get away with a 28t largest).
So an 11-27t cassette is really about the best you can do with the current set-up - I'd say this is different enough from your current 11-23 cassette that it's a worthwhile change to make on the hills. This would give you a bottom gear similar to what I have on my road bike (42/28 with 27" wheels). If you are doing regular hill climbs to keep the fitness up then this should be enough to get you up pretty much anything in one piece, though there'll still be a bit of out-of-the-saddle honking involved. To lower the gearing any further you'd have to replace the derailleur with a medium or long cage model.
TBH now that long cage derailleurs exist I don't understand why modern bikes aren't furnished with a lower low gear in 90% of cases, since most riders would be grateful for them at least some of the time!
http://sdeals.com/index.php/home/gears/rearmechs/product/13108-shimano-sora-rd-3300-rear-mech
If so, that gives a capacity of 29t and a maximum sprocket size of 27t (though you *may* be able to get away with a 28t largest).
So an 11-27t cassette is really about the best you can do with the current set-up - I'd say this is different enough from your current 11-23 cassette that it's a worthwhile change to make on the hills. This would give you a bottom gear similar to what I have on my road bike (42/28 with 27" wheels). If you are doing regular hill climbs to keep the fitness up then this should be enough to get you up pretty much anything in one piece, though there'll still be a bit of out-of-the-saddle honking involved. To lower the gearing any further you'd have to replace the derailleur with a medium or long cage model.
TBH now that long cage derailleurs exist I don't understand why modern bikes aren't furnished with a lower low gear in 90% of cases, since most riders would be grateful for them at least some of the time!
