Can you run 53/36 chainring combination ?

chocwege · Postby **chocwege** » Fri Jul 04, 2014 6:32 pm

I've just moved from a compact 50/34 to standard 53/39 cranks with my new Ultegra Di2 setup. I'm finding the 39 a bit tough in the hills (even with a 28 cog granny gear !). But I was finding the 50/34 wasn't really suitable for riding on the flats - I thought a 52/36 might be a good compromise.

The cost of a new inside chainring (ie 36 tooth) is only $25 but to get a new outside chainring (ie 52 tooth) is $180. So can I run a 53/36 combination or do I have to make a double change to 52/36 and pay the extra $$$ ? Or should I just HTFU ?

RonK · Postby **RonK** » Fri Jul 04, 2014 6:48 pm

I don't believe you can get a 36t ring with the correct BCD. That's why compacts exist.

KGB · Postby **KGB** » Fri Jul 04, 2014 6:55 pm

Yep, once you get down to about a 38 then the chain is practically running around the bolt circle.

If you ran the compact cranks, do you have a 53 that will fit? If so, throw it on and try.
Having said that, the difference between 50 and 53 is probably about 1 cog on the back (very roughly). 50x11 is a pretty big gear, if you can spin that out on the flats I'm damn impressed! New cassette?

Duck! · Postby **Duck!** » Fri Jul 04, 2014 7:36 pm

If you have a 6800 Ultegra crank you can try it, as all chainring combinations use the same BCD, otherwise regular cranks have a 130mm BCD vs 110mm for compacts. As KGB said, you won't get smaller than 38T on a standard BCD because the chain is virtually running on the bolts, and it's very rare to find bigger than 50T on compacts because the long mount arms on the big ring are subject to bending, breaking and general poor performance. Shimano's hollow chainring construction overcomes this, which is why they can now make 53T rings to suit the 110mm BCD (but the 4-arm design is incompatible with anything else).

So yes, on a 6800 (also 9000 Dura-Ace & 5800 105) you can run a 36/53 combination. That said, the 53 is ramped to match a 39T small ring, so shifting will suffer slightly .

chocwege · Postby **chocwege** » Fri Jul 04, 2014 7:45 pm

Yes it is Ultegra 6800 so it's the same BCD. I'm just not sure if the Di2 will cope with the smaller chainring as I remember reading somewhere that the size differential between the 2 chainrings was a limiting factor ?

Duck! · Postby **Duck!** » Fri Jul 04, 2014 8:10 pm

The front derailleur is rated for a maximum difference of 16T (34/50 or 36/52). However there's generally a bit of tolerance, so I don't think the 17T difference will push the friendship too far. You typically have problems when a big front difference is coupled to a wide cassette, but given 6800 is designed to accept up to 20T difference at the back (12-32 cassette), the 28 is within range, so you should be OK. As mentioned before the main (and then only slight) problem I can see is that the not-ideally-aligned ramping on the side of the big ring may cause a bit of roughness in front shifting.

Postby **mikesbytes** » Fri Jul 04, 2014 10:23 pm

My road bike has 53/39 running on bcd110, I brought it off a dutch guy who didn't like the compact rings it came with.

The trick with putting a 53 on bcd110 is to use chain rings that are cnc machined, for example http://www.miche.it/en/catalogo/catalog ... ovalsystem

jasonc · Postby **jasonc** » Sat Jul 05, 2014 7:45 am

a workmate ran 34/52 on a 6800 crank (mech groupset). was a bit noisier than 36/52 but it did work

it's cheaper to buy a crank with 36/52 than it is to buy the bloody chainrings.

Carrots · Postby **Carrots** » Sat Jul 05, 2014 9:49 am

Few more comments on the WW forum for the same topic...

http://weightweenies.starbike.com/forum ... p?t=125646" onclick="window.open(this.href);return false;

Sent from my iPhone using Tapatalk

chocwege · Postby **chocwege** » Sat Jul 05, 2014 2:19 pm

Thanks for the advice. Will pick up a 36 chainring and give it a go. $25 for the chainring v $180 for a new crankset so its worth a try.

Postby **mikesbytes** » Sat Jul 05, 2014 6:16 pm

chocwege wrote:Thanks for the advice. Will pick up a 36 chainring and give it a go. $25 for the chainring v $180 for a new crankset so its worth a try.

$25 that's cheap, which chain ring and where did you get it?

jasonc · Postby **jasonc** » Sun Jul 06, 2014 6:51 am

mike - http://www.bikebug.com/groupset-compone ... 36960.html" onclick="window.open(this.href);return false;

$25.99

HappyHumber · Postby **HappyHumber** » Sun Jul 06, 2014 8:03 am

mikesbytes wrote:The trick with putting a 53 on bcd110 is to use chain rings that are cnc machined, for example http://www.miche.it/en/catalogo/catalog ... ovalsystem

I think you'd be hard pressed to find 'rings in this day and age that aren't produced by CNC machines, TBH.

They'd have to be particularly nasty and/or cheap otherwise. Or some old Cold-war era stock dug up out of an Eastern-bloc warehouse.

CXCommuter · Postby **CXCommuter** » Sun Jul 06, 2014 8:54 am

RonK wrote:I don't believe you can get a 36t ring with the correct BCD. That's why compacts exist.

Maybe for shimano- SRAM you can- Cyclocross cranksets (46/36) are 130mm BCD so you can run 53/36 (I have done it).

mitchy_ · Postby **mitchy_** » Sun Jul 06, 2014 10:57 am

CXCommuter wrote:
RonK wrote:I don't believe you can get a 36t ring with the correct BCD. That's why compacts exist.
Maybe for shimano- SRAM you can- Cyclocross cranksets (46/36) are 130mm BCD so you can run 53/36 (I have done it).

sram CX cranks are very much 110BCD. it's impossible to run anything smaller than 38T on 130BCD.

HappyHumber · Postby **HappyHumber** » Sun Jul 06, 2014 11:36 am

You guys are being conned by all the mod-cons...

TA-Specialites Pro-5-Vis (or compatible) FTW! 26t through 56t, in a double, single or triple

warthog1 · Postby **warthog1** » Sun Jul 06, 2014 7:37 pm

RonK wrote:I don't believe you can get a 36t ring with the correct BCD. That's why compacts exist.

Looks like campag are following the industry leaders;

cyclingnews wrote:The 2015 Campagnolo Super Record crank with a 4-arm spider eliminates the compact-specific crank option. Now Campagnolo, like Shimano, has a bolt circle diameter that works with compact, semi-compact and standard chainrings

http://www.cyclingnews.com/news/new-cam ... first-look

CXCommuter · Postby **CXCommuter** » Mon Jul 07, 2014 12:20 pm

mitchy_ wrote:
CXCommuter wrote:
RonK wrote:I don't believe you can get a 36t ring with the correct BCD. That's why compacts exist.
Maybe for shimano- SRAM you can- Cyclocross cranksets (46/36) are 130mm BCD so you can run 53/36 (I have done it).
sram CX cranks are very much 110BCD. it's impossible to run anything smaller than 38T on 130BCD.

My SRAM 46/36T BCD is 130mm and runs a 53T on occasion- Absolute BS that they are 110mm BCD- it states 130mm BCD on the chainrings. They are 2012 Rival cranks

My fail- they are 46/38- 130mm BCD (just checked them at work)

DaveQB · Postby **DaveQB** » Fri May 05, 2017 2:28 pm

I know it's an old post but I used this thread when researching about going to a 53x36 on a 6800 crank with 6770 Di2 10 speed setup and just want to add my results for anyone else searching. Bought and installed the 36 chainring and it feels like it shifts the same as when I had the 53x39 setup; no noticeable difference, it's been great.