Compact Chainsets.

[TheCyclingRooster]

Hi to you all out there. What is the maximum number of teeth that can tolerated on a compact ?

Is there a formula whereby the tolerance range changes with a large ring - say 52T or a smaller yet still the larger of two at say 46T.

If the inner of two was only a 24T or perhaps a 26T would would the outer then be ?

Is the Compact governed by the ratios on the cassette ?

 

[S-Express]

For any double chainset, the max difference in teeth between the two chainrings is around 16.

 

[TheCyclingRooster]

For any double chainset, the max difference in teeth between the two chainrings is around 16.

Hi S- Express. Thank you for that info but when you say 'around' but how many more could one go - without trial and error and a load of playing about ?

 

[si_c]

Hi S- Express. Thank you for that info but when you say 'around' but how many more could one go - without trial and error and a load of playing about ?

Most road double front derailleurs have a maximum difference of 16 teeth as s-express says, this will be because the derailleur has to lift the chain from the smaller to the larger chainwheel, and if the difference is too great then shifting performance will be compromised. Practically you can probably go two either way if you don't mind that, but the only way you will know for sure is trial and error.

 

[TheCyclingRooster]

Hi si_c. Thank you for your reply. I will do a spot of experimentation.

 

[Lozz360]

Hi S- Express. Thank you for that info but when you say 'around' but how many more could one go - without trial and error and a load of playing about ?

Also, I wouldn't want to have a gap of more than 16t. You may be different, of course, but I find the gap going from 50t to 34t quite large even by changing up on the cassette at the same time as dropping to the smaller chain ring.

 

[swansonj]

At one stage I had a bike with 44/24 chainrings that worked fine. I can't remember what derailleur mechanism I used - quite possibly one that was designed for a triple.

 

[Fab Foodie]

Any touring or triple chainset mech should handle whatever set-up you want. What is more important is to have a long cage rear mech with the capacity to take the chain slack. Again a touring or MTB mech should work.
Back in the days of the first double chainsets it waa not uncommon to see 50/28 for the example. People bought TA chainsets to do this. Old beardy CTC and many old continental cyclists still use such a set-up with a many 23T max 5 speed block at the rear.
There's nothing new under the sun, just marketing and newbies :-)