I’m in the category of riders who should probably be riding a compact crank.
I have a 6 year old wired SRM and can’t lay out the cash to buy a new power meter so I need to stick with a 130mm BCD spider system.
(Even if I had the cash to buy a new wireless system I might not because the wired one that I have seems to be bullet proof. Never had a problem and the weight and aero penalty of the wire must cost no more than a few tenths of a second over an Olympic or even half-iron distance ride)
The smallest chain rings available to fit the 130mm spider are 50/38.
One of the reasons why I’m thinking about switching to the smaller chain rings is because I spend most of my time in the top half of the cassette when using my 53 and switching to a 50 would move me closer to the middle where the ratios are tighter and should make it easier to keep to my most comfortable cadence.
Does anyone have experience running 50/38? What do you think of it?
Love it. I put a 11-23 on the back for the most part. I can grind out in the big ring more often than I could with the 53. But I may just be stronger as well.
For the really crazy races like the Ohio TTT I could put a 11-26 on the back and have a slew of gears to choose from.
im wondering if 52/38 might be better. With a 50 front, you may sometimes run out of gear on tailwind/downhill sections, and unless you are very cadence sensitive there shouldn’t be much downside to a 52/51 front.
I race road so I don’t have a tri bike but my race bike is a 53/39 and my trainer/off season bike is a 50/36. In race scenarios the compact wouldnt be useful for me since I’m only in the small ring for steep stuff- I’d be downshifting either way.
Without knowing your training roads, w/kg etc…I’d say make mental notes of what gears you usually use on different roads, then figure out what cog that would put you in if you had the compact.
@90rpm using a 50x11 I’d get 32mph and up to 35mph spinning up to ~100rpm on a downhill or with a strong tailwind. For my ability that’s about where I’d decide to coast or ease back a little one effort anyway.
The theory behind the idea is that using a 50 x 23-11 puts me on the 14-15-16-17 for the majority of the rolling to flat courses that I ride. With the 53 I often have to go to the 19 and the ~12% change in ratios between 53x17 and 53x19 creates larger changes in cadence than I like. I frequently wish I had an 18. There are cassettes with an 18 but not many.
A potential downside is that because the smallest ring that will fit on the standard spider is 38 meaning that the overall ratio range going from 53/39x23-11 to 50/38x23-11 is narrower. It’s a potential downside but I can’t find a reason to believe it would be an actual problem.
@90rpm using a 50x11 I’d get 32mph and up to 35mph spinning up to ~100rpm on a downhill or with a strong tailwind. For my ability that’s about where I’d decide to coast or ease back a little one effort anyway.
The theory behind the idea is that using a 50 x 23-11 puts me on the 14-15-16-17 for the majority of the rolling to flat courses that I ride. With the 53 I often have to go to the 19 and the ~12% change in ratios between 53x17 and 53x19 creates larger changes in cadence than I like. I frequently wish I had an 18. There are cassettes with an 18 but not many.
A potential downside is that because the smallest ring that will fit on the standard spider is 38 meaning that the overall ratio range going from 53/39x23-11 to 50/38x23-11 is narrower. It’s a potential downside but I can’t find a reason to believe it would be an actual problem.
You couldn´t have said it better, many peolple think they have Cancellara´s legs.
That’s probably on the limit of what most FD’s could handle…actually my ideal is 52/38, so just losing 1 tooth off each…I definitely won’t bother replacing my chainrings just to go that route.
My training roads have alot of 10-12%+ grades and that is the type of races I like to do- short power climbs. I race alot on a 12-27- so I have the 53x24 without going big/big, and having the 39x27 is really nice when everyone is grinding @ 4-500w/15%+ and I’m sitting and spinning comfortably.
The theory behind the idea is that using a 50 x 23-11 puts me on the 14-15-16-17 for the majority of the rolling to flat courses that I ride. With the 53 I often have to go to the 19 and the ~12% change in ratios between 53x17 and 53x19 creates larger changes in cadence than I like. I frequently wish I had an 18. There are cassettes with an 18 but not many.
I’m not a bike mechanic, but can’t you just buy an 18 tooth cassette ring and swap it for, say, your 12 tooth cassette ring? You’d then still have your 11 (although you stated you don’t use it that often) and you’d have 14-15-16-17-18-19. If that doesn’t work, there’s also the 12-23 option (Shimano) that has the 18. I dropped to a compact q-ring setup (which is supposedly equivalent to a 52 on the power stoke) , and I sometimes miss the 53 tooth. I do like that I don’t have to drop to the small ring as often, though, so I’m sticking with it for now.
Somewhat related question…What is the difference between A type chainrings and B type chainrings? And can I easily tell?
As I recall the difference is in the position of the pins and shaped teeth to optimize shifting from either a 39 (B) or a 42(A). I may have them switched.
Was in a similar situation with a wired 130 bcd Srm. Switched to 110th bcd Quarq and loving it. I do have a set of SRM 52/38 130 BCD rings just lying around if you ate interested.
Another option is to run a mtn bike cassette but you will need a long cage RD.
Where can you get a 36 in 130mm? I thought the smallest was 38.
I have a 53/38 on my tri bike, and it’s awesome. I think Jack Mott might be right though, switching to a 52 or a 51 might be better in terms of having more usable gears.
im wondering if 52/38 might be better. With a 50 front, you may sometimes run out of gear on tailwind/downhill sections, and unless you are very cadence sensitive there shouldn’t be much downside to a 52/51 front.
unless I am missing something.
After waffling about throwing down for a compact, I decided to first try 52/38 on my standard, and have been really happy with combo. On crappy long courses, I can throw on my 12-27 in back and survive anything. Tighter cassette can be tossed on for flatter stuff. Maybe it’s all in my head, but I like the 52/38 versus 53/39.
looks like you have done the math and are good to go then! trust the math!
I do a lot of short TTs around austin that are windy and sometimes you get up to 40+ mph so I need my 53!
@90rpm using a 50x11 I’d get 32mph and up to 35mph spinning up to ~100rpm on a downhill or with a strong tailwind. For my ability that’s about where I’d decide to coast or ease back a little one effort anyway.
The theory behind the idea is that using a 50 x 23-11 puts me on the 14-15-16-17 for the majority of the rolling to flat courses that I ride. With the 53 I often have to go to the 19 and the ~12% change in ratios between 53x17 and 53x19 creates larger changes in cadence than I like. I frequently wish I had an 18. There are cassettes with an 18 but not many.
A potential downside is that because the smallest ring that will fit on the standard spider is 38 meaning that the overall ratio range going from 53/39x23-11 to 50/38x23-11 is narrower. It’s a potential downside but I can’t find a reason to believe it would be an actual problem.
Thanks Jackmott,
Once in while I do end up racing when it’s blowing a gale and more than once in a while I ride or race courses with 9 or 10% hills so I probably would end up spinning out with a tailwind or going downhill and curse myself for changing the 53. It’s just the large portion of the time that I seem to be on the 53x17 or 53x19 and miss the 18.
Someone mentioned the idea of buying an 18 and swapping it in for the 19.
Would that be possible? Would the jump from 18 to 21 cause any problem with shifting?