Tech Question

Noangel72

Hi,

I need to replace the chainrings on my Trek 1.2, original chainset is a
Bontrager Sport 53/39. Will I be able to purchase any Shimano chainring or am I restricted to Bontrager chainrings?

Thanks.

niceonetom

As far as I know you can get rings from any manufacturer as long as you get them for the right chain width - 9 speed, 10 speed etc.

papac

right chain width - 9 speed, 10 speed etc.

and correct bolt circle diameter.(BCD) 130mm in this case.

Might be worth noting that if you look around online you can sometimes pick up a new, half decent crankset for similar money to a pair of chainrings.

Noangel72

...in fact I noticed that a chainset (for example a Sora doublering) would cost less than the two rings.......I wonder if then I would have to replace the bottom bracket too....and with what model...octalink?...68mm or 70mm????

papac

I wonder if then I would have to replace the bottom bracket too

Depends. BB must match chainset. Imo if bike has enough mileage to wear out chainrings it probably is no bad idea to replace bb while your rooting around in that dept. anyways.

Almost certainly you have english bb which afair is 68mm.

Noangel72

....might wait and upgrade the entire groupset!...thanks for the tips!

papac

...might wait and upgrade the entire groupset!...thanks for the tips!

Don't want to wreck your head but selling your current bike and buying a new one is sometimes a better option.

Especially this time of year when people are looking for entry level s/h bikes.

e.g If you or someone you know has an axa insurance policy you can get 15% off all bikes in halfords.
This would then cost 1060 euros.
http://www.halfords.ie/webapp/wcs/stores/servlet/product_storeId_11101_catalogId_15551_productId_502001_langId_-1_categoryId_212536

If you got 300 for your trek you would have a nice new shiny carbon bike, Sram rival equipped, for a few quid more than a groupset.
My 2cents.

Noangel72

good point...I was thinking that myself!.....I am also moving back to Italy in a couple of months so I could trade in there for an Italian bike.....I just bought Mavic Aksium wheels so I will either upgrade the groupset now or trade in for a new bike .....don't know yet....but I like the 1.2 Trek frame.....

niceonetom

Noangel72 wrote: »

I need to replace the chainrings...

papac wrote: »

pick up a new, half decent crankset for similar money to a pair of chainrings.

Noangel72 wrote: »

....might wait and upgrade the entire groupset!

papac wrote: »

...selling your current bike and buying a new one is sometimes a better option.

From new chainrings to new bike by post #7. Record?

Noangel72

Lumen

niceonetom wrote: »

From new chainrings to new bike by post #7. Record?

Seven Degrees Of Planet-X?

papac

Record?

I was gonna suggest it but I thought 11 speed campag might be a step too far.

kumate_champ07

Noangel72 wrote: »

Hi,

I need to replace the chainrings on my Trek 1.2, original chainset is a
Bontrager Sport 53/39. Will I be able to purchase any Shimano chainring or am I restricted to Bontrager chainrings?

Thanks.

not sure what bottom bracket you have but this is awesome value if your bcd is 130mm

http://www.chainreactioncycles.com/Models.aspx?ModelID=2647

I might be interested in going halves if you wanted the chainrings and I could have the crank?

cdaly_

Errm, how do I figure out what BB I have on the bike?

Chips Lovell

cdaly_ wrote: »

Errm, how do I figure out what BB I have on the bike?

If you can't actually see it, then I'd go by what cranks you have, i.e. they'd only be compatible with a certain BB type.