Straight swap replacement for Truvativ Isoflow cranks?

easybiker

Need to replace my ageing Truvativ Isoflow crankset (42-32-22) on my trusty 8-speed Hardrock MTB. Chain is Shimano HG40 6/7/8-speed. Anyone aware of a straight replacement? Was looking at Truvativ 5D on ebay, or Suntour XCT or SRAM S600. Finding the right technical info to retain the same chainline seems impossible. Please help me someone!

CitizenLee

You can adjust chainline with spacers, and most aftermarket cranksets should fit with the correct bottom bracket. Not sure I'd replace them with either of those two though.

What year Hardrock is it? I think they all have a 68x113mm BB.

easybiker

It's a 2007 Hardrock. BB is Powerspline. Still waiting for the WD40 to soak in before I can get the cranks off to measure the BB.

If you don't like my 3 suggestions, what would be your inclination for a set of comparable quality to the Isoflows?

CitizenLee

easybiker wrote:

It's a 2007 Hardrock. BB is Powerspline. Still waiting for the WD40 to soak in before I can get the cranks off to measure the BB.

If you don't like my 3 suggestions, what would be your inclination for a set of comparable quality to the Isoflows?

Here's specs so you don't have to measure

http://www.specialized.com/us/en/bikes/ ... port#specs

68 x 113mm

What's your budget for new cranks?

cooldad

BB depends on the cranks, so check the docs that come with the cranks for correct BB size.

It might not be the same size as the OE.

easybiker

CitizenLee wrote:

easybiker wrote:

What's your budget for new cranks?

As little as possible, of course, for something that will last between 5,000 - 10,000 miles of mixed on road / off road riding. You tell me how much I need to spend, please.

CitizenLee

I just think if you're upgrading it may as well be an actual upgrade.

Still trying to keep it cheap I go for a Shimano Deore Tripleset for £54.99

http://www.chainreactioncycles.com/shim ... prod106873

Don't worry about it being 10 speed, makes no difference for cranks.

You'd also need a 68/73mm Hollowtech II Bottom Bracket.

http://www.chainreactioncycles.com/shim ... -prod34674

I'd also be inclined to change chain and cassette after so many miles too, so they all wear evenly.

http://www.chainreactioncycles.com/shim ... -prod67295
http://www.chainreactioncycles.com/shim ... rp-prod779

So, £61.98 for crankset and BB, or £81.37 all in.

easybiker

Thanks, CitizenLee, I'll look at that. I've already changed the chain and cassette, it's only now that it's started slipping on the chain rings. I guess they had adapted to the old stretched chain. If I want to save money on the £61.98, might it be worth looking at just replacing the chain rings? The actual Truvativ rings are no longer available.

CitizenLee

No probs

In that case you would just need a triple ring set with same amount of teeth per ring and same BCD (bolt spacing). I think the Isoflow is 64/104mm BCD (64mm being the granny ring, and 104mm being middle and outer) but you will need to check that. Might not work out much cheaper though.

easybiker

Thanks CitizenLee, it has really helped to know that chain rings labelled 9 speed are OK in an 8 speed system. I see that all chain speeds have the same internal width, 3/32th of an inch. I'm much more confident now. I've ordered 22T and 32T Deore and 42T Alivio from ChainReaction for £23 all in.

CitizenLee

Glad I could help. That's worked out pretty cheap and should keep you going for a good while longer

easybiker

To cap it all, they fitted perfectly with no filing or spacers required. Goes like a dream now.

CitizenLee

easybiker wrote:

To cap it all, they fitted perfectly with no filing or spacers required. Goes like a dream now.

Haha nice one! Always a good feeling when things go smoothly!