MTB chainset with more teeth

[Dermot]

Hi,

I've been making a few alternations to my 5 year old Cannondale badboy. The bike has a 9 speed cassette (SRAM) and triple Chainset (Shimano Deore). I cycle to work practically every day. It's 8 miles each way so I know the route.

I moved from 44mm tyres to 25mm (599-25) and the difference is vast. I am spending 60% of my ride in the top gear and it doesn't always keep up. I've been looking and I cannot see a MBT chainset with more than the 44 teeth I already have. I don't need a triple either. I've never used the inner ring. AFAIK, shimano's only double chainset are the XT range. For that price, I could get an Ultregra or a 105. It would be a double and have more teeth. There is a Shimano FC-3550 Sora 9-Speed that is reasonably priced but it is compact and has just 46 teeth so not a big jump.

The question is will it work? Can you fit a Ultregra or similar on a MBT frame?
Thanks in advance,
Dp.

 

[dan_bo]

http://www.middleburn.co.uk/chainrings_atb.php

 

[Dermot]

Interesting. Those atb rings have 5 bolt holes. My Shimano Deore (M590, I think) requires 4 and I'm not sure if those spaces will work. I'll email that supplier and see if they stock something compatible.
Thanks for the link.
Dp.

 

[ohnovino]

The Shimano Deore FC-M591 has a 48-tooth big ring

 

[I like Skol]

The M590 comes in other 'flavours'. I have the 26/36/48 variety and also never touch the 26T unless by accident (I thought about whipping it off but it does no harm and it's there should I ever need it?). Also, what cassette are you running? If the smallest sprocket is a 12T then swapping to a cassette with an 11T as the smallest actually makes a big difference.

I can see that a 44T chainring would be limiting for a fast road commute

 

[Dermot]

I hadn't noticed that and I've spent a lot of time surfing the Chain Reaction site. I did replace the outer ring a couple of weeks ago as it was worn and one tooth was missing. I also have a wobble in the cranks which I think indicates a problem somewhere, possibly the bottom bracket. In short, it might make sense to replace the whole chainset. I was also considering replacing the rear cassette too as, like the front, it's also worn. I had my eye on this HG80 and chain. I can't see how many teeth that cassette has, from the picture, it looks like 11.

There's a few options to consider now. It would be good to get some return on the cost of the outer ring I recently bought. I have to address the wobble in the cranks and I will need to replace the cassette in the near future too.

Thanks for the suggestions. I need to weight up the options.
Dp.

 

[I like Skol]

Chain reaction appear to have rolled out a new website today and it's all a bit clunky with information missing. Try a different website or wait a few days for CRC to get their act together.

 

[gbb]

Bear in mind you may have to change the BB as well...to take the large chainring away from the chainstay. I replaced a small outer (can't remember the size now) with a larger, and it immediately fouled the driveside chainstay. I didnt progress further, itwasnt that important to me, but it did occur to me if I put a wider axled BB in to compensate, would that change the chainline drastically ?
Worth checking the current gap between chainring and stay ?

 

[Dermot]

Chain reaction appear to have rolled out a new website today and it's all a bit clunky with information missing. Try a different website or wait a few days for CRC to get their act together.

Yes I noticed that too. I feel their pain. I've been there.

 

[cyberknight]

learn to spin faster 44x12 at 90 rpm is 25.5 mph

 

[Dermot]

Haven't spent the afternoon thinking about it, I've come to the conclusion that I should address the problem I appear to have with the crankset wobbling. I'll start a new thread for that and see what people think.
Thanks,
Dp.

 

[byegad]

Note all of the details of your crankset, and ring SPA Cycles. They'll almost certainly have a 48 tooth outer ring for your bike.

 

[Dermot]

I don't think I'll replace just the outer ring. I only bought the current one 3 weeks ago. I should get some return on investment from it. However, I might be persuaded to replace the entire Chainset in the not too distant future because I am not happy with the amount of wobble on the cranks at the moment. The problem is, I like to do this stuff myself, I get a kick out of it, but I don't have all the tools - can't believe what some people want for a torque wrench - so upgrades this this can come up lumpy.