Hi, Need some chain ring advice. I have a Dawes Synthesis MTB/Hybrid circa 1996.

[David Lyons]

I have a Shimano LX 8 speed set up with 22 - 34- 42 front chain set (mid chain ring has been replaced) and a 11 - 32 rear cassette. I am pretty heavy and do quite a few long challenging rides with panniers and just about manage on the very steep hills but lack speed on the flat trying to keep up with my fitter mates with more conventional touring ratios. Thinking of changing the granny ring to 24T and the outer ring to 46T. What do you think? Its a LX group set at present. Guess I could change the whole chain set but cant go too mad cost wise. Your thoughts would be appreciated.

Yes I would to save up and buy a Galaxy but not an option at the moment!

 

[RecordAceFromNew]

If I were you I would get this amazing bargain if the existing chainset is worn. Depending on the model code (FC-mXXX on the inner face of the crank arm) of the existing LX you might not even need a new bottom bracket if it is still good. If you need a new bb a new UN55 is under £13. Assuming you have 26" tyres 90rpm at the pedals with 44x11 should take you to 28mph on the flat - which I suspect even Cav can't keep up all day on a mtb/hybrid...

 

[David Lyons]

Thanks, that's worth thinking about. Current Chainset is a FC M563 170mm. Its 8 speed as well.

 

[RecordAceFromNew]

Thanks, that's worth thinking about. Current Chainset is a FC M563 170mm. Its 8 speed as well.

Your M563 and that M442 from CRC have exactly the same bottom bracket requirement.

 

[biggs682]

that looks a bargain

 

[sreten]

Hi,

Your spinning out 42/11 on the flat ?

A 46 will give you 9% more gearing, which is typically about 1 gear.
Why you would change your small chainring to give less gearing,
(again typically about 1 gear) is a bit beyond me in your logic.

Higher gearing will not make you faster on the flat. Most bikes
have plenty of gears for the flat and high gears are for downhill
and/or a strong wind behind where you can spin out a flat gear.

Lacking speed on the flat compared to fitter people has nothing
to do with incorrect gearing. You are presumably slower period.

FWIW I have 52/42 and 14,16,18,20,22,24,28 on my road bike.
Your 42/11 is a bigger gear than my 52/14 but might be lower
due to MTB versus road wheels, depends on your tyre sizes.
Still on the flat I go fastest 52-18/20, I don't need more gears.

42/11 is plenty enough gearing on most bikes. Given you
seem OK on hills but lose out on the flat, that points to
rolling, i.e. lack of proper rolling on the flat.

The right tyres at the right pressures optimise rolling, and
a heavier person needs fatter tyres than a lighter person.
Note that tyres that feel fast generally are not fast.

I'd look at your tyres to go faster on longer runs. There
is so much myth out there regarding tyres its hard to
to be sensible. The fastest tyres for mere mortals
have nothing to do with what the racers use.

rgds, sreten.

 

[evo456]

Out of stock but this crank set may suit your needs. Affordable too.

http://www.rosebikes.co.uk/article/...fc-m-411/aid:287945?forcedefaulttemplate=true

 

[David Lyons]

Hi,

Your spinning out 42/11 on the flat ?

A 46 will give you 9% more gearing, which is typically about 1 gear.
Why you would change your small chainring to give less gearing,
(again typically about 1 gear) is a bit beyond me in your logic.

Higher gearing will not make you faster on the flat. Most bikes
have plenty of gears for the flat and high gears are for downhill
and/or a strong wind behind where you can spin out a flat gear.

Lacking speed on the flat compared to fitter people has nothing
to do with incorrect gearing. You are presumably slower period.

FWIW I have 52/42 and 14,16,18,20,22,24,28 on my road bike.
Your 42/11 is a bigger gear than my 52/14 but might be lower
due to MTB versus road wheels, depends on your tyre sizes.
Still on the flat I go fastest 52-18/20, I don't need more gears.

42/11 is plenty enough gearing on most bikes. Given you
seem OK on hills but lose out on the flat, that points to
rolling, i.e. lack of proper rolling on the flat.

The right tyres at the right pressures optimise rolling, and
a heavier person needs fatter tyres than a lighter person.
Note that tyres that feel fast generally are not fast.

I'd look at your tyres to go faster on longer runs. There
is so much myth out there regarding tyres its hard to
to be sensible. The fastest tyres for mere mortals
have nothing to do with what the racers use.

rgds, sreten.

Thanks,

Wanted to change the 22 to a 24 to keep the front changer within a 22T limit otherwise I would have to change it so I was told. Also changing up from 22 to 34 is not very reliable coming off a climb. Not sure I understand your thinking on high speed gearing on the flat. Surely 46/11 would be fastest for me than 42/11 if I can keep the pedal rate high up?