Centaur group on my Cross bike: Crank/Ring question.

[zott28]

Hi all, sorry if this has been discussed, but I've found nothing thru search.

I have a lightly used Centaur group that I decided to put on a cross frame. The crank is 39/53, I'd like to switch that out. What are my option for getting new rings that would be cross friendly. Should I just look into a new crank set, and if so, any suggestions on which one would pair nicely with this Centaur group?

Thanks,
Zott.

[fourflys]

I'm pretty sure you're stuck with buying a compact crankset... I believe the bolt pattern/size is going to preclude you from replacing those chainrings with anything small enough to be usefull... I'd look around for an older square taper BB/crankset, that's what I put on my cross bike... post a WTB in the classifieds on here, I was able to pick a NOS centaur CT set...

I could be wrong though and if I am, I'm sure I'll be corrected...

[Bruce K]

I was looking at www.cyclocrossworld.com and they have chain rings as low as 42t outers but they are only for 110 or 130 bolt patterns.

BK

[zott28]

If I change the outer to a different brand would I need to change the inner to keep the ramps the same?
I want to keep it a double for trail riding.
Thanks for the help guys.

[fourflys]

If I change the outer to a different brand would I need to change the inner to keep the ramps the same?
I want to keep it a double for trail riding.
Thanks for the help guys.

I'm not sure the brand is that important, the issue is the bolt pattern that BK talked about... you have to make sure you match the correct BCD, look on your crankset now and look for either 110 or 130 BCD (I'm sure it's 130, but double check...)

[r_mutt]

if it's a campy standard crank, 53/39, then it's 135 BCD.

you can't go any smaller than 39 on the inner ring on campy's 135 BDC, but Specialties TA make an 135 BCD 46 outer. that would leave you with 39/46 chainrings- suitable for cross.

the other option is to buy a campy ct crank which has 110 BCD, and choose any ratio you want.

http://cyclocrossworld.stores.yahoo.net/spectapinout.html

[John M]

What you need for cross depends on the terrain you ride/race, your fitness level and what kind of gearing you run in the back.

Strong guys can race something like a 46/39 or 48/39. That also works well for flat races. I am a weakling racing in a hilly area, so I run a 48/34 compact on my cross bike with a 12-26 in the back. Also, with the 34, I can sometimes ride hills that other guys are running up.

I'd say figure out what gearing you need. If you need a front chainring smaller than 39T, you'll need a different crankset. Cranksets with 130BCD will accommodate a 38T small chainring, 110BCD can go down to 34.

[v531xc]

I agree with John M. I use a single 38t up front with a 12-26 in the back. It really depends on your terrain.

There might be brands other than TA who make smaller rings for running a cross double with 135bcd. Also, BBG makes 135bcd bashguards if you decide to run a single ring.

[Ken Robb]

take a look at Sugino too.

[dogdriver]

White Industries' VBC crankset

http://www.whiteind.com/cranks/roadcranks.html

has nearly limitless chainring combos. Call them (an actual human who knows of what they speak will answer) with compatibility questions.

Don't own one of these, but run a White drive train on my SS and can't speak highly enough of the quality...

Best, Chris

[fogrider]

I had the same problem...the thing is, if he don't have the gearing on the bike, how does he know if its right for his terrain? but I don't race, I like to have a little more gearing just in case.

I found a race face square taper crank and slapped it on the campy bb. the race face is way stiff and rock solid. I don't think they make the same model currently, but I think they have a cx crank in their line up...not sure what bb the current cranks require.

[gforce]

Another option is just run a single 42 or 39. Many racers just use a single
chainring for simplicity. I find it offers enough range and allows me to focus
on the terrain and dismounts more. There are plenty of guys on single speeds
that are really fast.

[zott28]

I think I would run a single up front if I was only racing, but I plan on riding the fire trails in Marin a lot more than racing. My commute bike is set up 1x9 and it's fast enough for what I'm doing.
It looks like the best set up would be something in the mid 30's and something in the mid 40's which would mean I need a new crankset.

[djg]

If you move to Centaur CT, there are some nice aftermarket rings from PMP worth looking at.