crank advice

[stu_sirrus]

I've got a 2011 sirrus sport. Got a cheap shimano altus crank on at the moment. I've done about 5000 miles which people say is reaching the end of its life. I'm considering upgrading to a road style bike. Would a deore 9 speed fit to my bike with alivio gear system 8 speed without changing the deraileur and shifters. Advice much appreciated.

 

[Cycleops]

If your chainring is worn you can simply replace it, you don't need to replace the cranks, if that is what you are asking. I thought the Sirrus was a road bike, all be it a hybrid. I don't see how changing to a nine speed will make a difference.

 

[Nigelnaturist]

I've got a 2011 sirrus sport. Got a cheap shimano altus crank on at the moment. I've done about 5000 miles which people say is reaching the end of its life. I'm considering upgrading to a road style bike. Would a deore 9 speed fit to my bike with alivio gear system 8 speed without changing the deraileur and shifters. Advice much appreciated.

You would need to change the shifters, to convert to a 9 speed, and as Cycleops says it wont make much difference, though it would enable you to have smoother stepping through your gears, probably not worth from a cost and time point of view, I am looking at changing my 7sp to either an 8 or 9 simple because I would like a lower and higher gear on both sides, my set up is so that I spin out easily downhill, but in general use its fine, if I had the fitness it would manage 17-19 with the gearing I have, on the flat.

 

[MattHB]

When you say 'upgrade to a road style bike', what are you actually trying to achieve? More road gearing? Drops?

It's a little unclear.

Incidentally, I can't imagine a modern crank wearing out in only 5000 miles.

 

[RecordAceFromNew]

I've got a 2011 sirrus sport. Got a cheap shimano altus crank on at the moment. I've done about 5000 miles which people say is reaching the end of its life. I'm considering upgrading to a road style bike. Would a deore 9 speed fit to my bike with alivio gear system 8 speed without changing the deraileur and shifters. Advice much appreciated.

There are a few things to consider.

First off has the chainset really reached the end of its life? What made you think so? Generally the tell-tale sign is cogs appearing shark-toothed, but it is not completely straightforward because even new chainsets have some cogs that are shark-tooth shaped. You could google for a high resolution photo of an identical new chainset (e.g. see below) and compare the tooth profile.

Secondly chainsets need to match the bottom bracket to deliver the same chainline to not cause problems or require new front mech. While Deore is Shimano's mtb chainset just like the Altus, I am pretty sure all current Deores have Hollowtech 2 BB while all Altus are square tapered/octalink, that is assuming all else (e.g. large ring size) being equal without giving rise to other potential issues. So unless the BB is worn or to be replaced at the same time, you may wish to to bear that in mind, and measure the chainline before changing to ensure new will be similar to old. You can check to see if a BB is worn by slipping the chain off the chainset and then rotate the cranks and feel/hear for rumble/play if any.

Hope it helps.

 

[stu_sirrus]

Thanks a lot guys. My dilemma is whether it is worth upgrading the current system to a 9 speed or change for a road style hybrid. The basic model of the sirrus is relatively heavy but I got a free shimano r500 wheelset. I put carbon forks on. But is still only basic. Will do some research on how.much everything youvguys have suggested to make the deore work. Is the alivio crank much different. The shops have said 5000 miles would potentially cause the chain and cassette to wear. Im away but when I get back I will check for wear. Thanks people. Much appreciated

 

[HLaB]

The sirrus is already a road style hybrid (aka a flat bar road bike) adding an extra cog won't make it faster You are batter replacing with another set of 8sp chain rings if your are worn out but 5,000 miles is a little short mine still has the original chainrings which have done over 10,000 road miles (its now a turbo bike).