Please excuse the probably fairly obvious questions but am quite new to bike 'tuning' 😎 I am looking at raising the gearing on my mtb (poc mid 90's Raleigh Firefly), its curently an 18spd with 42,34,24 chain ring on the front and 14-28 6spd freewheel (newley replaced with shifters) on the back. Is it just the case of changing the 42 tooth chainring for a larger one? I never use the smallest one (24t) but do need to drop into the 34t sprocket for some of the steep hills on my commute. If it is a case of just getting a new chainring, how much realistic difference will a couple of extra teeth make? Will this cause any problems with the front derauiler?
Im not looking at spending loads on this bike, I've just upgraded the brakes (avid sd's) and got some slicks. Thats about all its getting aside from maintenance as I leave it chained up at work and at the gym which arn't great areas 🙁 .
Shimano make a MF-HG50 11-28 7 speed, spin on. Check the clearance between the 14t of the 6 speed and the frame drop out, it may fit straight on, if not, spreading the frame a few mm and adding some spacer washers to the axle is a simple operation.
A Crankset with a 48 tooth Big Ring, Shimano FC-TX71 28/38/48, is quite cheap also. I use a FD-C051 Front Derailleur with this crankset.
For the tyres, Conti Sport Contact 26x1.3 or Ultra Gator Skins in 26x28mm are good performers.
Please excuse the probably fairly obvious questions but am quite new to bike 'tuning' 😎 I am looking at raising the gearing on my mtb (poc mid 90's Raleigh Firefly), its curently an 18spd with 42,34,24 chain ring on the front and 14-28 6spd freewheel (newley replaced with shifters) on the back. Is it just the case of changing the 42 tooth chainring for a larger one? I never use the smallest one (24t) but do need to drop into the 34t sprocket for some of the steep hills on my commute. If it is a case of just getting a new chainring, how much realistic difference will a couple of extra teeth make? Will this cause any problems with the front derauiler?
Im not looking at spending loads on this bike, I've just upgraded the brakes (avid sd's) and got some slicks. Thats about all its getting aside from maintenance as I leave it chained up at work and at the gym which arn't great areas 🙁 .
Thanks in advance,
Ed
You'll probably need a new chain. Check that the capacity of your rear derailleur is adequate for the larger chainring (or at least post the model number of the RD). You'll need to post the BCD (bolt circle diameter: 94, 104 or 110mm) of the crankset, or at least its model number. Check that you are able to move the front derailleur up the seat tube. It's all possible. Up to 48T seem to be available, but to go that big you will have to lock out your 24T granny ring completely with the lower limit screw. 46T would allow you to keep the granny ring, assuming that you have an RD capacity of 22T. Post your details and the replies that you get will then make more sense than this excess of information that I have just written! PS: George's post regarding a new freewheel with a smaller top gear sprocket probably makes more sense than a chainset change, if you can get hold of one.
