Stronglight chainset replacement.

[Paulus]

Just a quick question.
My square taper Tiagra triple chainset is worn out 52/42/32.
Could I replace it with a Stronglight Escape triple 48/38/28 without replacing the BB? It's also square taper
As I'm getting older I think I need a bit lower gearing.

 

[bikingdad90]

Yes most likely as the width with be the same. The issue will be chain stay clearance with the 28 and having to fiddle with the front mech as it’ll need to move down the seat tube.

 

[C R]

Check the spec for the spindle size required. Each square taper chainset is designed for a particular spindle length, so you need to make sure that the bottom bracket you currently have in your bike is the correct size spindle for your new chainset.

 

[Sharky]

Have you exhausted the cassette options?

 

[T4tomo]

Yes most likely as the width with be the same. The issue will be chain stay clearance with the 28 and having to fiddle with the front mech as it’ll need to move down the seat tube.

Will it? If a 32 clears the stays what problem do you foresee with a 28?

To the OP BB length may be an issue, if you can't find specs of both online then try it with current BB and then get another if it doesn't align properly.

You will need to lower the FD, for the 52->48 change for slick shifting

 

[Ian H]

Spa Cycles have a good range of cranksets. Their own brand is good quality. You can customise the ratios. They'll also advise on bottom bracket compatibility if you ask them.

 

[Paulus]

Have you exhausted the cassette options?

The cassette is fairly new, so as the chainset is worn I thought I'd go down that route.

 

[Ajax Bay]

My square taper Tiagra triple chainset is worn out 52/42/32.
Could I replace it with a Stronglight Escape triple 48/38/28 without replacing the BB? It's also square taper

No
https://sheldonbrown.com/bbsize.html
My 4403 Tiagra requires a 113mm BB spindle.
Its replacement is this:
https://www.spacycles.co.uk/m8b17s1...Triple-Chainset-With-Stronglight-Zicral-Rings
But your Stronglight Escape triple requires a 122mm BB spindle (see second clip)

 

[Paulus]

No
https://sheldonbrown.com/bbsize.html
My 4403 Tiagra requires a 113mm BB spindle.
Its replacement is this:
https://www.spacycles.co.uk/m8b17s1...Triple-Chainset-With-Stronglight-Zicral-Rings
But your Stronglight Escape triple requires a 122mm BB spindle (see second clip)

View attachment 761723

View attachment 761730

So I'll need a BB as well.
Thank you.

 

[Jameshow]

Will it? If a 32 clears the stays what problem do you foresee with a 28?

To the OP BB length may be an issue, if you can't find specs of both online then try it with current BB and then get another if it doesn't align properly.

You will need to lower the FD, for the 52->48 change for slick shifting

It should be fine.

I'd suck it and see, but if your BB isn't smooth I'd change it at the same time.

 

[C R]

It should be fine.

I'd suck it and see, but if your BB isn't smooth I'd change it at the same time.

@Ajax Bay found that the stronglight replacement needs a BB with a longer spindle. With the shorter spindle there's a risk of the inner chainring being too close to the frame.

 

[Jameshow]

@Ajax Bay found that the stronglight replacement needs a BB with a longer spindle. With the shorter spindle there's a risk of the inner chainring being too close to the frame.

Agreed and the chain line would be out by 9mm not a small amount!

 

[ColinJ]

I put a Stronglight triple from Spa on my CAAD 5. It started off as a 48/38/28 but when the 38 tooth ring wore out I replaced it with a 36. That gives nicer steps between the rings and I find that using a 36 with my 12-30 cassette lets me do most of my riding on that middle ring.

I just found my original posts about the upgrade. Apparently, I fitted a 115 mm bottom bracket. The conversion did involve some bodging because the bike started off with a 53/39 double chainset. Shifting down to the little ring can sometimes be iffy so I think that a few extra mm bottom bracket length would have been ideal. Any extra length would give the front mech that much more travel relative to the chain. Not that that would apply to @Paulus's bike because he already has a triple.

 

[Ming the Merciless]

Agreed and the chain line would be out by 9mm not a small amount!

Would it, or would the extra 9mm be split across both sides of the BB?

 

[C R]

Would it, or would the extra 9mm be split across both sides of the BB?

It would be split, assuming a symmetrical spindle, but the risk of being too close to the frame is still there, and the derailleur adjustment may be tricky.