Gearing down...

[timdownieuk]

I'd appreciate some advice please.

I recently bought one of these from a Forum member: http://www.bikepedia.com/quickbike/Bike ... odel=Sutra

A really nice bike, and in lovely condition, and just about original spec. Before I bought it I had the notion that the gearing would be slightly too high for me, and so it's proving.

It has a 14-25 rear cassette fitted, and I know the obvious thing to do is to change this for something like a 14-34 but the problem's not really at the rear, it's the road triple chainset up front.

With that in mind, could I get away with replacing the current chainset with something like a 48-36-26 Deore chainset which would give me a very useable set of ratios and retain the rather nice close ratio gearing at the back?

I recently moved from a 11-26 8 speed cassette to a 11-34. I was worried about the big gaps but in practice it feels absolutely fine. I don't carry more than a few pounds of load and haven't missed my 42 or 32 front rings since I disposed of them.

Obviously depends on you local terrain but I reckon I can get up most hills up to 20% on a 52x34

[Bicycler]

I recently moved from a 11-26 8 speed cassette to a 11-34. I was worried about the big gaps but in practice it feels absolutely fine. I don't carry more than a few pounds of load and haven't missed my 42 or 32 front rings since I disposed of them.

Obviously depends on you local terrain but I reckon I can get up most hills up to 20% on a 52x34

A 40" bottom gear would be too high for me when the going got lumpy! Do you really get much use out of the 125" top gear? There was a time in the not so distant past when professional racing cyclists topped out at about 100"!

The lower the better for me nowadays. Even MTB triples/cassettes will often give a 100" top gear and that will do me fine

[timdownieuk]

I recently moved from a 11-26 8 speed cassette to a 11-34. I was worried about the big gaps but in practice it feels absolutely fine. I don't carry more than a few pounds of load and haven't missed my 42 or 32 front rings since I disposed of them.

Obviously depends on you local terrain but I reckon I can get up most hills up to 20% on a 52x34

A 40" bottom gear would be too high for me when the going got lumpy! Do you really get much use out of the 125" top gear? There was a time in the not so distant past when professional racing cyclists topped out at about 100"!

The lower the better for me nowadays. Even MTB triples/cassettes will often give a 100" top gear and that will do me fine

No, I don't often spin out in top gear (other than down steep hills) but I'm too mean to ditch my beautiful TA Cyclotourist 52 ring just for the sake of having a better gear range.

[Bonefishblues]

Thanks all, appreciate the different perspectives given.

It sounds as if the best bet is to either go for the Spa XD2 with 48/36/26 with a new BB and hope that the 105 front won't take umbrage (surely it shouldn't - it's not that big a change, is it?). If it does, I'm grateful for the reference to the IRD Alpina - but they do look rather like the proverbial Rocking Horse poo in terms of availability, having had a quick search around.

Either that, or change all 3 chainrings on the FSA - but that ends up just as, if not more expensive than buying a new chainset it seems? Which sensibly-priced rings (130/74 BCD) would people recommend, if I did decide to go this route?

[Erudin]

From: http://www.peterwhitecycles.com/chainrings.asp

"My most popular chainrings are 48 - 38 - 26 and 24 tooth replacements for Shimano's 9 speed Ultegra and 105 triple cranks. This makes for a much better range of gears if you're touring. Most of Shimano's 9 speed cassettes start with a 12 tooth cog, and some start with 11, which is wasted when your largest chainring is 52 teeth and you're carrying a heavy load. Reducing the size of all the chainrings lets you actually use all nine cogs in back. Why have nine speeds if you can't use them all? 48,38,24 shifts very smoothly with the Ultegra 9 speed front derailleur and STI shifters. When you change the size of the outer chainring, you'll need to change the position of the front derailleur. With every tooth reduction, the derailleur needs to be lowered by 2mm."

From: http://forum.ctc.org.uk/viewtopic.php?f=5&t=63551&start=15#p542901

CJ has a system for measuring the min small chain ring. If I remember correctly...

Thanks but not quite. It goes like this:

To measure how low you can get, engage your existing inner ring with the smallest rear cog you really need to use with inner. Lean an elbow on the right pedal to tension the chain and see what's the biggest allen key you can poke underneath it in the front mech cage. The key figure is 2mm per tooth. So if an 8mm key goes in there, you can reduce the inner ring by 4T.

With a 50 outer, you may well be able to use a 24 inner - with the inner (i.e. taller) half of the cassette at least. A Jump-Stop is always a wise precaution, even with the size of inner the chainset originally came with. And a bigger jump isn't a problem if you flick up a couple of cogs with the right hand at the same time as you drop to inner with the left. I used to double-shift back in the days of down-tube friction controls (poked the left lever forward with my thumb whilst tugging the right with two fingers) but now we have STI and Ergopower anyone can do it - so do it!

If you're planning also to reduce the outer ring, you can make a further equal reduction to the inner - assuming there's scope to move the front mech down the frame, 2mm for each tooth reduction in the outer. TA make a 38 middle to fit 130bcd, so 24,38,48 is possible on those cranks, but more cost.....

[Valbrona]

I think lots of people like something smaller than a 38t middle ring on their triple, hence the preference for 74/110BCD or MTB-specific cranksets.

[NetworkMan]

As implied above, I don't understand that if all the OP wants to do is go to a 26T inner in order to get 1 gear lower he doesn't just pop one on his existing chainset. It is possible that the chain will go too slack or rub the cage in the higher two or three gears on the little ring but personally I don't use those gears anyway. Total cost £9 in dural or £7 in steel!

I did a similar trick on my touring bike with 7 speeed triple. I reduced the size of the inner from 28T to 24T while keeping the existing 38T and 48T outers. The chain goes slack in the highest one or two gears but I don't care.

[NetworkMan]

.... and the two mm rule goes like this...
1T is 1/2 inch or 12.7 mm. A reduction of 1T reduces the ring radius by 12.7/(2 * pi) = 2.02 mm. QED

[Bonefishblues]

As implied above, I don't understand that if all the OP wants to do is go to a 26T inner in order to get 1 gear lower he doesn't just pop one on his existing chainset. It is possible that the chain will go too slack or rub the cage in the higher two or three gears on the little ring but personally I don't use those gears anyway. Total cost £9 in dural or £7 in steel!

I did a similar trick on my touring bike with 7 speeed triple. I reduced the size of the inner from 28T to 24T while keeping the existing 38T and 48T outers. The chain goes slack in the highest one or two gears but I don't care.

OP wants, ideally, a 26 inner, a 36 middle and a 48 outer and is looking for the most elegant way to achieve this

If I went for a 110/74 BCD touring chainset such as the Spa ones, would my chainline be an issue as it's being suggested it might be if I went for a Deore mountain chainset with the same rings?

[Bicycler]

Spa's own tourer runs an XD-2 and a road front derailleur.

[Bonefishblues]

Spa's own tourer runs an XD-2 and a road front derailleur.

Doh! So it does. This must therefore be the right answer I think!

It needs a new BB, but that's no issue, given the chainset's remarkable value to start with it's still cheaper than a Deore. Do you happen to know whether Spa will tweak the chainring size on request, as I'd be looking for 36/26 rings as opposed to their 38/28 "out of the box"?

It's really funny they didn't mention this when I was speaking to them, rather than steering me elsewhere, as it's exactly what I'm after.

[niggle]

My previous road bike was a Spesh Allez SportTriple, with 30/39/50T chainset and 9spd 12-25 cassette. When I transferred the components on to a new build based around a Genesis Equilibrium I was due to do the Dartmoor Devil audax in a month or so, so I fitted a £6 Onza Buzzsaw stainless steel 26T inner ring, lowering the bottom gear from 32" to 28", which was fine for the DD, did not walk any of the hills that year

However in day to day use around Cornwall the jump between inner and middle rings annoyed me a bit so when the cassette wore out last year I replaced with a 12-27 and swapped the inner ring to a Dural 28T for about £10. Bottom gear remained the same but now the jump from inner to middle and vice versa is quite acceptable to me. All these mods have kept the spec just within the official capacity of the Tiagra medium cage rear mech. Note only the largest two sprockets change when going to 12-27 from 12-25 9spd.

[reohn2]

The front mech will handle a 46t big ring easily I'm using road mechs on four bikes one is a 105(2005 as it happens) and one of which has a 44t outer and is wildly out of spec,but works just fine with 9sp Shimano STI's.
If you decide to stick with the original c/set a 26t inner will fit but whether the mech has the capacity with a 52t outer I couldn't say,you'll need to check the gap on the trailing/bottom edge of the mech cage.
I'd go for Spa's own chainset,which has a 110BCD so you can go smaller on the middle(34t min) and inner(24t min) rings with a 48t outer.
TBH I buy the their TD2 cranks(5 arm) with Spa's own rings,which are very good quality indeed,don't forget you'll need crankbolts,with a Shimano 115 or 118mm UN55 BB,very durable and stylish to boot

[NetworkMan]

The front mech will handle a 46t big ring easily I'm using road mechs on four bikes one is a 105(2005 as it happens) and one of which has a 44t outer and is wildly out of spec,but works just fine with 9sp Shimano STI's.

Do you know the model numbers of the levers and front changers? My Tiagra 9 -speed is from about 2001 and has FD-4403 and FC-4403. I know that things changed - FD-4503 etc. It looks as if on the newer shifters it 'overshifts' since the mech does not occupy the same position when shifting down from big as it does when shifting up from bottom. http://www.shimano.com/media/techdocs/content/cycle/SI/TIAGRA/FD-4503/SI_5K80A_En_v1_m56577569830606982.pdf I guess this is to make the change work better - rather as one does with a non-indexed downtube shifter except that the STI does not back off after the overshift.

[Bonefishblues]

The front mech will handle a 46t big ring easily I'm using road mechs on four bikes one is a 105(2005 as it happens) and one of which has a 44t outer and is wildly out of spec,but works just fine with 9sp Shimano STI's.
If you decide to stick with the original c/set a 26t inner will fit but whether the mech has the capacity with a 52t outer I couldn't say,you'll need to check the gap on the trailing/bottom edge of the mech cage.
I'd go for Spa's own chainset,which has a 110BCD so you can go smaller on the middle(34t min) and inner(24t min) rings with a 48t outer.
TBH I buy the their TD2 cranks(5 arm) with Spa's own rings,which are very good quality indeed,don't forget you'll need crankbolts,with a Shimano 115 or 118mm UN55 BB,very durable and stylish to boot

Thanks, that's helpful advice.

I notice Spa say 110mm BB, you're recommending longer - any particular reason?