Longer Chain Moving from Compact to Semi Compact?

[bpsmith]

Am all but ready to fit a new Ultegra 52-36 Chainset, in place of the Gossamer Pro 50-34. Just wondering if I desperately need to fit a new chain as there's plenty of life left in the current one?

Instinct suggests that I should do it now, to go with the new chainrings, but it does seem rather wasteful if the length will be fine without.

 

[si_c]

Should be fine, provided your derailleur has the capacity - just put it in big/big and see if the derailleur looks pulled forward, if it does, just avoid that combination.

 

[bpsmith]

During the Summer I totally perfected the front derailleur setup and can comfortably use literally any gear combination now. I can honestly say, that I never stray onto the 2 largest sprockets whilst in the big ring, so unlikely to be an issue then. Cheers.

 

[si_c]

During the Summer I totally perfected the front derailleur setup and can comfortably use literally any gear combination now. I can honestly say, that I never stray onto the 2 largest sprockets whilst in the big ring, so unlikely to be an issue then. Cheers.

It probably won't be, it's only a 2 tooth increase on the large sprocket - this equates to the chain needing to be one half link longer in size to wrap around the larger diameter chainring for the same derailleur movement.

 

[Ajax Bay]

ready to fit a new Ultegra 52-36 Chainset, in place of the Gossamer Pro 50-34. Just wondering if I desperately need to fit a new chain

If your chain is on the short side now then the current length chain may be too short. Most riders try to avoid large to large but sometimes it just 'happens' more easily in the dark ime. When on large/large (50-28(say)) now if your cage points no higher than 5 o'clock, you should be OK with the 52 as it will only need half an inch more chain. Otherwise - new chain.
Do you know how many miles you've done on the current chain. A thousand is enough to minimise wear on the cassette.

 

[bpsmith]

If your chain is on the short side now then the current length chain may be too short. Most riders try to avoid large to large but sometimes it just 'happens' more easily in the dark ime. When on large/large (50-28(say)) now if your cage points no higher than 5 o'clock, you should be OK with the 52 as it will only need half an inch more chain. Other wise - new chain.
Do you know how many miles you've done on the current chain. A thousand is enough to minimise wear on the cassette.

Cheers. Will have a glance later. Not got around to doing the job yet, as want to order a chain in readiness.

Done roughly 1,311.7 miles on this bike and roughly 1,560.1 miles on the other. Strava is very useful for recording data like this.

I use a chain checker and replace chains on around 0.75 on the tool. Bearing in mind that a new chain comes on just under 0.5, I think that I am doing well considering they’re both currently on 0.6.

I have replaced the last 2 chain on 0.75 and the cassette on this bike looks nigh on the same as the other bike, despite having done 3 times the mileage. Currently at 4,558.2 and original cassette. Do I appear to be getting good mileage?

 

[bpsmith]

Here’s how the derailleur looks in the extreme cross chain.

 

[Ajax Bay]

Done roughly 1,311.7 miles on this bike . . . .
I use a chain checker and replace chains on around 0.75 on the tool. Bearing in mind that a new chain comes on just under 0.5, I think that I am doing well considering they’re both currently on 0.6.
I have replaced the last 2 chain on 0.75 and the cassette on this bike looks nigh on the same as the other bike, despite having done 3 times the mileage. Currently at 4,558.2 and original cassette. Do I appear to be getting good mileage?

You've done well to get that mileage from your cassette and it is a compliment to your systematic chain checking and changing. I'd expect a new chain to be at zero % elongation, but whatever.

Here’s how the derailleur looks in the extreme cross chain.

That chain is already on the short side (imo). Going from 50 to 52 will make it too short. You've had 1300 miles from that chain. New chain, one link (one inch) longer would be my recommendation. See how long the chain/cassette combination lasts. The prudent route, which might end up cheaper in the event, would be to replace both chain and cassette when you change the chainset.

 

[bpsmith]

You've done well to get that mileage from your cassette and it is a compliment to your systematic chain checking and changing. I'd expect a new chain to be at zero % elongation, but whatever.

That chain is already on the short side (imo). Going from 50 to 52 will make it too short. You've had 1300 miles from that chain. New chain, one link (one inch) longer would be my recommendation. See how long the chain/cassette combination lasts. The prudent route, which might end up cheaper in the event, would be to replace both chain and cassette when you change the chainset.

The current chain length was set using the Big-Big method, without going through the derailleur, with a full extra link added. Been fine so far, although do agree that it would probably be too short.

Have ordered a Dura Ace chain this evening in readiness. Got a silly price on a Gabba 3 SS Jersey at the same time, but that’s another story.

With respect to the cassette, I was thinking of getting a closer ratio one for the aero bike, so might swap that cassette onto this bike as it’s done a third of the mileage.

Cheers for the advice btw.

 

[slowmotion]

I've no idea about the wear on your current chain, but this chain length calculator is the dogs bollocks.

http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html

 

[Dirk]

Am all but ready to fit a new Ultegra 52-36 Chainset, in place of the Gossamer Pro 50-34. Just wondering if I desperately need to fit a new chain as there's plenty of life left in the current one?

Instinct suggests that I should do it now, to go with the new chainrings, but it does seem rather wasteful if the length will be fine without.

I went the other way on my Focus with Ultegra Di2 - from 52/36 to 50/34. I didnt have to alter the chain.

 

[Ajax Bay]

this chain length calculator is the dogs bollocks.

Quick calculation but:
1) Requires you to know/go and measure chainstay length and know/inspect/count number of teeth on large sprocket and large chainring.
2) Then requires the fettler to times by 2 and count to 114 (say) before cutting the new chain..
The OP @bpsmith uses large to large plus one link (one inch). I wonder whether that's not the cat's whiskers?

 

[bpsmith]

Ok, here's my plan:

Swap Ultegra Semi Compact Chainset, 11-28 Cassette and Chain from Bike 1 to Bike 2. All three items have been on bike since new and the Chain should be the right length on the basis that the chainstay's on Bike 2 are literally only 3mm longer on Bike 2 than Bike 1.

That leaves me free to fit the brand new Chainset and Chain to Bike 1, along with a new closer ratio cassette at the same time. I will have a spare chain and cassette, albeit used, that I can put on a spare pair of wheels with crap tyres for Turbo use. Happy days.

 

[andrew_s]

Here’s how the derailleur looks in the extreme cross chain.

That's OK.
You wouldn't want to ride cross-chained like that regularly, but you do want to be able to change into big/big.
If the chain's too short to allow it, and you accidentally click the shifter once too often, things may break. It's most likely to happen in the dark when you can't glance at the chain to keep track of what gear you are in, and the most likely damage is a broken chain, bent chainring or a bent derailleur hanger.

 

[bpsmith]

I agree. I don’t like a bodge. I like my gear set up how intended, even if I never use the extreme crossed chain scenario.