Changing triple chainset query

ForumNewbie

Hi, I'm thinking about changing the Tiagra 52/40/30 triple chainset on my steel Audax bike for a Tiagra 50/39/30 triple. I have a 105 front mech, and just wondering whether it would have to be lowered a bit on the frame to work with the smaller chainset? Am I right to assume the shifter would still work okay?

keezx

Front mech a bit lower and you're ready.....
Not much difference anyway....

desweller

It'll work fine.

Curious as to why you're doing it though?

ForumNewbie

DesWeller wrote:

It'll work fine.

Curious as to why you're doing it though?

Thanks for the responses. The reason I'm thinking of doing this is that I've been trying to up my cadence rather than grind in bigger gears, and I've found that on hills I've been dropping to the granny ring more than usual to maintain cadence, which is fine, but I think I'd be better with a 39 middle ring than a 42. Also I don't really need a 52 big ring - a 50 would be fine.

I also sometimes feel pain/weakness in my left knee when pedalling, which I think has come from trying to push too big gears so I think the 39 middle ring will help there. I've also noticed the cranks on my current set-up are 175 mm which I've never really thought about before, but just read that there are probably too long for my legs as I am only 5'8" tall, so that may have been contributing to my knee problems. I see that the Tiagra 50/39/30 comes with 170 or 175 mm cranks, so I think the 170s would be better for me.

desweller

I've got 170s on my tourer and they definitely encourage more spinning compared to the 175 I used to have on my roadie, so IMO you're on the right track.

If you're getting knee problems it's worth getting your setup checked. I find that adding some occasional running into my training also helps strengthen my knees, particularly at this time of year. Now I will get flamed by people whose knees have been knackered by running.

ForumNewbie

DesWeller wrote:

I've got 170s on my tourer and they definitely encourage more spinning compared to the 175 I used to have on my roadie, so IMO you're on the right track.

If you're getting knee problems it's worth getting your setup checked. I find that adding some occasional running into my training also helps strengthen my knees, particularly at this time of year. Now I will get flamed by people whose knees have been knackered by running.

Thanks Des, I've had the bike 8 years, but the frame is too big for me really, but adjusting saddle position and adding a short adjustable stem has made it very comfortable for last 5 years, although not very aerodynamic, but as I'm in my mid-50s not that bothered. I probably wouldn't 'pass' a bike fit with that bike though. I was thinking I would get a 50/39/30 anyway, but only now realised I would benefit from shorter cranks as well, so I think I will definitely do it, but may wait till after winter.

I also have a carbon bike with a compact chainset, but I must admit I prefer a triple as think it's better for cadence. I might even think of changing that to a triple next year, but probably the front mech and shifter would also need changing?

desweller

You'd definitely need to change the front mech; some older iterations of Shimano left hand shifters would do triples and doubles, but I think they knocked it on the head for the recent versions.

I'm led to believe you can't get a triple at all for 11-speed.

earthvspace4XTuUWcX

With your carbon bike I would suggest fitting a 48 or even a 46 chain ring, depending on what cassette you are running. Far simpler and cheaper than having to change the crankset, front mech and shifter. In your situation I think you will find this much better than a standard 50/34 compact.

ForumNewbie

xdoc wrote:

With your carbon bike I would suggest fitting a 48 or even a 46 chain ring, depending on what cassette you are running. Far simpler and cheaper than having to change the crankset, front mech and shifter. In your situation I think you will find this much better than a standard 50/34 compact.

Hi xdoc, my carbon bike has an 11-28 cassette, but I could do with a lower gear than 34/28 for the steepest hills. I know a lot of people would find that fine, but I'm in my mid-50s and not that strong so could do with the extra gear, and that's why I'd like the triple with the 30 ring, as well as for the lesser drop from 50 to 39 rather than 50 to 34.

It's a Cube Agree bike and they do or did sell them with triples when I bought it 3 years ago. In hindsight I wish I had gone for a triple but I thought compact was the way to go as most new carbon/race type bike here in the UK has 2 rings rather than 3.

ElectronShepherd

The other option to consider is to switch to an MTB cassette on the rear. If (and it's an important if) the cable pull is the same, you could fit a long cage MTB derailleur and cassette. Moving from 28 tooth at the back 34 tooth would make a big difference. You'd need a new chain as well, since the current one would be too short.

desweller

The trouble with compacts and MTB cassettes and all that jazz is they're just not as convenient. I'm a big fan of triples. Bloody hate compacts. I've got a 50/36 in-between chainset to try on my next bike but I could easily see it being converted to a triple if I don't like it.

Front derailleurs are pretty cheap. If you're patient then I'm sure you can pick up some 2nd hand shifters for not much money (my current pair of 105 shifters cost me £45).

rafletcher

DesWeller wrote:

You'd definitely need to change the front mech; some older iterations of Shimano left hand shifters would do triples and doubles, but I think they knocked it on the head for the recent versions.

I'm led to believe you can't get a triple at all for 11-speed.

The mech is not the shifter. He has a triple shifter AND a triple mech. It'll work fine with the slightly smaller big ring, even without lowering it. I just changed my outer chainring from a 52 to a 50 and didn't touch the mech (I forgot until I read this post!) Works fine.

No 11sp triples though, you're correct there.

ai_1

DesWeller wrote:

The trouble with compacts and MTB cassettes and all that jazz is they're just not as convenient. I'm a big fan of triples. Bloody hate compacts. I've got a 50/36 in-between chainset to try on my next bike but I could easily see it being converted to a triple if I don't like it.

Front derailleurs are pretty cheap. If you're patient then I'm sure you can pick up some 2nd hand shifters for not much money (my current pair of 105 shifters cost me £45).

Best of both worlds if you want an all rounder is something like my the setup on my old Tricross Sport Triple. It has a triple and the ability to run a very wide range cassette.
It's predominantly Tiagra with a 50/39/30 triple and a Deore long cage rear derailleur.
So, you can put what would normally be a MTB cassette on the back AND you have a 30 tooth chainring at the front. The gear range in it's original spec was 30/32 at the small end up to 50/11 at the big end. Ideal for getting a slightly overweight beginner over nearly any terrain. That triple and large sprocket combo got me over many climbs (at a fast walking pace) that most would have said I wasn't ready to tackle. However, once I'd gotten a little fit, I changed the rear cassette. For my mix of flat and mountainous rides I soon decided a 12-27 cassette was a better match to the triple. It delivered closer ratio spacing and once I'd gotten a bit fitter, it still gave me an adequate gear option to climb 15%+ gradients.
Having said that I'm enjoying my new compact equipped bike too.

desweller

rafletcher wrote:

DesWeller wrote:

You'd definitely need to change the front mech; some older iterations of Shimano left hand shifters would do triples and doubles, but I think they knocked it on the head for the recent versions.

I'm led to believe you can't get a triple at all for 11-speed.

The mech is not the shifter. He has a triple shifter AND a triple mech. It'll work fine with the slightly smaller big ring, even without lowering it. I just changed my outer chainring from a 52 to a 50 and didn't touch the mech (I forgot until I read this post!) Works fine.

No 11sp triples though, you're correct there.

Read it again, he's got a double on his carbon bike.

ForumNewbie

DesWeller wrote:

rafletcher wrote:

DesWeller wrote:

You'd definitely need to change the front mech; some older iterations of Shimano left hand shifters would do triples and doubles, but I think they knocked it on the head for the recent versions.

I'm led to believe you can't get a triple at all for 11-speed.

The mech is not the shifter. He has a triple shifter AND a triple mech. It'll work fine with the slightly smaller big ring, even without lowering it. I just changed my outer chainring from a 52 to a 50 and didn't touch the mech (I forgot until I read this post!) Works fine.

No 11sp triples though, you're correct there.

Read it again, he's got a double on his carbon bike.

Sorry for any confusion - I shouldn't have mentioned my carbon bike. At the moment I am just thinking of changing the triple on my Audax bike - the 50/42/30 for a 50/39/30, and it sounds like it shouldn't need the front mech changing or maybe not even moving it down the frame a bit.