Confused about gearing
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sgw":sxvcnccm said:
it just wouldnt shift but would mangle just about everything if accidentally shifting.
I used 53/30 with a short reach mech, long chain and Ging tensioner for commuting on an MTB
I try to use as few gears as possible but keep the ring for 'just in case' moments. Heres how I 'got away with it':
The big cheese is undoubtedly much stronger than me.legrandefromage":12bt6jkx said:
Just say you were in 36/30 and felt the need for 26/30 but mistakenly pushed with your left thumb towards 46/30, instead of clicking with your left finger. The chain isn't long enough so it won't actually happen, but is your left thumb strong enough to break the chain? Mine isn't. Would you break the rm by forcing it so horizontal? No, it will go horizontal. Might you bash the rm against the chainstay in the attempt? Possibly.
If that's the way you ride, it might be as well to keep the chain long enough for big/big, but I did say 'provided you stay in the correct chainring'. But if you're the kind of rider who changes to the appropriate chainring well before you run out of sprocket options, I doubt whether you would ever encounter any difficulty.
The cage is marked:-
Max 28t
Total 28t
I am surprised to see max and total the same, I would expect Total to be the max + ??? I have obviously misunderstood something else!
Anyway I am inclined toward 46, 34, 24 & 12/28. Am I correct in understanding that would work as intended with a short cage?
Can anyone suggest any possible improvement on that for old fart style off road work and decent cruising on flat track or road?
A bit OT (please excuse)
legrandefromage That is the bike I am aiming at.
I was a bit shy at revealing so on a forum where so much beautiful, original and showroom quality work is displayed. I though it might be considered "disrespectful" to such a classic frame. Mind you, I am not sure that my addition of a rack and leaving the finish naturally aged bare matt grey with authentically crazed decals might not prohibit me from the Z.O.C. anyway
How do you find it as a commuter lgf? What mudguards and bars and hows the geometry with drops?. I have always preferred a frame one size up from what most shorties like me would use. I think this should help getting a more roadie (spit) style stance. May I use your pic to show people that I am not mad, or at least not the only one?
(should I have started another thread?)[/u]
Max 28t
Total 28t
I am surprised to see max and total the same, I would expect Total to be the max + ??? I have obviously misunderstood something else!
Anyway I am inclined toward 46, 34, 24 & 12/28. Am I correct in understanding that would work as intended with a short cage?
Can anyone suggest any possible improvement on that for old fart style off road work and decent cruising on flat track or road?
A bit OT (please excuse)
legrandefromage That is the bike I am aiming at.
I was a bit shy at revealing so on a forum where so much beautiful, original and showroom quality work is displayed. I though it might be considered "disrespectful" to such a classic frame. Mind you, I am not sure that my addition of a rack and leaving the finish naturally aged bare matt grey with authentically crazed decals might not prohibit me from the Z.O.C. anyway
How do you find it as a commuter lgf? What mudguards and bars and hows the geometry with drops?. I have always preferred a frame one size up from what most shorties like me would use. I think this should help getting a more roadie (spit) style stance. May I use your pic to show people that I am not mad, or at least not the only one?
(should I have started another thread?)[/u]
sgw":2kwads2i said:
Max only states the maximum cog size that can be used. This is by the way independent of short/medium/long cage. Most manufacturers are on the safe side with this, so you might get away with 30t as well.
Total teeth is (max cog - min cog) + (max chainring - min chainring). So in your case (28-12) + (46-24) = 38t. The total teeth is actually determined by the cage length, the ability to take up chainslack (short/medium/large) and shows that your medium cage is by far not enough to handle the combo you would like.
It seems that you have to make some choices now...
I don't blame you! What people are saying is not wrong, but the general implication that if you go outside the parameters, your house will burn down and your legs will fall off is something of an exaggeration. As I have explained, if you avoid using crazy gear combinations, the inadequacy of your 28t capacity will have no practical consequence.
If it's worrying you though, why not buy a replacement long cage rear mech and set your mind at rest? I see that somebody in the MTB For Sale is asking £12 for an LX RD-M565, which is from c1995 and has a capacity of 38t. Alternatively look out on eBay for an XT RD-M735 or 737 SGS (not GS), both of which have a capacity of 39t and generally cost c£15-20.
If it's worrying you though, why not buy a replacement long cage rear mech and set your mind at rest? I see that somebody in the MTB For Sale is asking £12 for an LX RD-M565, which is from c1995 and has a capacity of 38t. Alternatively look out on eBay for an XT RD-M735 or 737 SGS (not GS), both of which have a capacity of 39t and generally cost c£15-20.
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MTB's with drops are an acquired taste, the frame had done around 40,000 miles by that time so I was not worried about a period correct build.
Middle rings are for decorative purposes only on my builds and are basically there for something to look at (or hold the outer ring on). I never bothered with the rules of rear mechs and teeth count and just went with what ever worked. With too short a chain, I was once on the 'big ring' and shifted up into the largest cassette sprocket bending the mech, mech hanger and other expensive bits (but not on the Zaskar, some experimental crap prior to that).
That set-up was something like a 53t/ 30t with a short cage mech, long chain and tensioner as mentioned before. Mudguards were whatever would fit.
Middle rings are for decorative purposes only on my builds and are basically there for something to look at (or hold the outer ring on). I never bothered with the rules of rear mechs and teeth count and just went with what ever worked. With too short a chain, I was once on the 'big ring' and shifted up into the largest cassette sprocket bending the mech, mech hanger and other expensive bits (but not on the Zaskar, some experimental crap prior to that).
That set-up was something like a 53t/ 30t with a short cage mech, long chain and tensioner as mentioned before. Mudguards were whatever would fit.
one-eyed_jim
Old School Grand Master
It's not a question of thumb strength. Once the chain is picked up by the chainring, it's your leg strength that completes the shift. The chain isn't usually the first thing to give: it's more likely to be the chainring or derailleur hanger.Anthony":1sm9nhw1 said:
A more likely scenario is sprinting in the big chainring to crest a rise and running out of gears. It's easy to forget that the chain is too short to allow the bail-out shift from 46/26 to 46/30. Once the big sprocket picks up the chain it's the same situation as before: something has to give. It might be the chainring (which is seeing quite a big lateral load under cross-chaining) it might be the sprocket (likewise) or it might be the derailleur hanger. If that puts the derailleur cage into the wheel, that can lead to a host of other problems, all in less than a turn of the cranks.
It's easy to say "just avoid big-big" - but I know I'm not always aware of which sprocket the chain is on at a given moment.
