Is my gear range wide enough?

[mcb2080]

Hi. I have signed up to do a supported LEJOG through my work in August, really looking forward to attempting this.

I have a Ridgeback Nemesis hybrid bike with a shimano alfine 8 speed hub, the front ring is a 45 tooth with a 20 tooth rear sprocket.

Do I have enough of a gear range to tackle the big hills or will I have to get a bike with a double cassette?

I have done plenty of 50 and 60 miler's so I think my bike should be comfortable for doing the LEJOG but I am a just wondering about the hills as the most I climb on an outing is about 800 feet.

According to map my ride the hardest climb I have is a cat 5, which I can do sitting in my saddle on the lowest gear.

533 ft Start Elev 1050.0 ft Max Elev 1860.0 ft Gain -1880.0 ft Descent Distance Elevation Grade Cat Start End Length Min Max Avg. Max

7.53 mi 8.78 mi 1.25 mi 777 ft 985 ft 3.1%

http://www.mapmyride.com/routes/view/18670038

Cheers

Ps, all the threads here are great for giving advice and motivation.

 

[snorri]

Your link says the route is private, so not accessible for comment.
I'm sure you'll be fine, with support you will not be carrying a load so should be OK.

 

[mcb2080]

Your link says the route is private, so not accessible for comment.
I'm sure you'll be fine, with support you will not be carrying a load so should be OK.

Hi snorri and thanks for the reply. hadn't realised the route was marked as private, I have unlocked it now.

Yeah, we will not need to carry much as there is a mini bus to support us.

I have been trying to gauge what is the category of the hardest hills on LEJOG but map my ride doesn't seem able to show them for some reason, maybe just too much info for about a 1000 mile ride.

I just don't want to get caught out with a hill that I have to push the bike up....lol, I want to cycle the whole lot.

Thanks again

Mark

 

[snorri]

I think the steepest hills you will encounter in Scotland are Berriedale on the A9 between Helmsdale and Lybster, and Culnakirk between Drumnadrochit and Beauly. Perhaps, if you are going that way, you could put these sections in to Mapmyride and see what comes up.

 

[RecordAceFromNew]

According to spec an Alfine 8 with a 20T cog at the back is equivalent to a 12-38 cassette, so with the 45T at the front it is delivering a range of roughly 30" to 97". For comparison purpose the lowest gear is equivalent to the 34T small ring of a compact double chainset with a 29T cog at the back. In terms of high it is equivalent to a 48T large ring in front with a 13T cog at the back.

To answer your question imho you are not really worse off than most cyclists with a double chainset and a cassette, and it would cost a lot to change because the cost of shifters, drivetrain as well as rear wheel will be incurred.

If you feel the lowest is not low enough the simplest and cheapest solution is to change the 45T to something smaller. If the chain is not worn it can simply be shortened.

 

[mcb2080]

I think the steepest hills you will encounter in Scotland are Berriedale on the A9 between Helmsdale and Lybster, and Culnakirk between Drumnadrochit and Beauly. Perhaps, if you are going that way, you could put these sections in to Mapmyride and see what comes up.

Thanks snorri, I will give that a try.

 

[mcb2080]

According to spec an Alfine 8 with a 20T cog at the back is equivalent to a 12-38 cassette, so with the 45T at the front it is delivering a range of roughly 30" to 97". For comparison purpose the lowest gear is equivalent to the 34T small ring of a compact double chainset with a 29T cog at the back. In terms of high it is equivalent to a 48T large ring in front with a 13T cog at the back.

To answer your question imho you are not really worse off than most cyclists with a double chainset and a cassette, and it would cost a lot to change because the cost of shifters, drivetrain as well as rear wheel will be incurred.

If you feel the lowest is not low enough the simplest and cheapest solution is to change the 45T to something smaller. If the chain is not worn it can simply be shortened.

Thanks very much for the technical explanation, I thought my gears where no where near enough range wise.

As for replacing the front 45T, I hadn't even thought of that, in fact I placed a bid on a road bike on ebay last night, bloody smirnoff....lol

Would the smaller front T have to be an Alfine or would any front ring do?

As for gear range, could you give me an idea of ideal front T size for gear range comparable to an ideal set up for tackling LEJOG.

Once again, thanks for your very clear explanation.

 

[mcb2080]

Just having a quick google and came across a post similar to mine where the guy changed the rear cog to a 22T nexus sprocket.

Would this be just as effective as lowering the front chain ring, as it is only £8 for the back, not sure of cost for the front chain ring yet.

I have two spare alfine chains, so I am ok with what ever way I change the drive set up.

EDIT

Seems the alfine has a 39T front ring at a cost of £70-£80

So seems I have three choices to make:

45 x 22 or a 39 x 20 / 39 x 18, I have an 18T lying in my shed.

I have replaced the bottom bracket on my bike so I have the correct tool for taking the front ring apart.

 

[corshamjim]

Just having a quick google and came across a post similar to mine where the guy changed the rear cog to a 22T nexus sprocket.

Would this be just as effective as lowering the front chain ring, as it is only £8 for the back, not sure of cost for the front chain ring yet.

I have two spare alfine chains, so I am ok with what ever way I change the drive set up.

Personally I would change the rear sprocket from 20t to 22t. In fact I did just that with my SA 5-Speed recently (now a 3-speed - long story). At that price you can give it a try and if you decide it makes your top gear too low change back again easily. The only disadvantage over reducing the size of the front chainwheel is that you are adding some weight not reducing it -it's up to you to decide whether that's important or not.

 

[mcb2080]

Personally I would change the rear sprocket from 20t to 22t. In fact I did just that with my SA 5-Speed recently (now a 3-speed - long story). At that price you can give it a try and if you decide it makes your top gear too low change back again easily. The only disadvantage over reducing the size of the front chainwheel is that you are adding some weight not reducing it -it's up to you to decide whether that's important or not.

Yeah, I think I will try a 22T first as see how it goes, I found a gear ratio comparison on sheldon brown for the shimano nexus 8 speed so hopefully it is the same gear ratios.



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From the above table the 39 / 20 has a lower ratio than a 45 /22 but for the price of only having to change the rear sprocket, I think I will try this option first.

Thanks again for everyone's help, much appreciated.

 

[dellzeqq]

mcb - how fit are you? I'd have thought that your problem on a LEJoG would be distance, not hills. I've done Berriedale on a 39/21 and it wasn't difficult. I'm sure RecordAceFromNew is correct, and if you have the equivalent of a 30 inch gear you'll do Berriedale with ease. Helmsdale and Shap go on and on, but they're not steep.

If you do stop on Berriedale it's no tragedy - there's a graveyard on the left hand side with some moving epitaphs on them.

 

[mcb2080]

mcb - how fit are you? I'd have thought that your problem on a LEJoG would be distance, not hills. I've done Berriedale on a 39/21 and it wasn't difficult. I'm sure RecordAceFromNew is correct, and if you have the equivalent of a 30 inch gear you'll do Berriedale with ease. Helmsdale and Shap go on and on, but they're not steep.

If you do stop on Berriedale it's no tragedy - there's a graveyard on the left hand side with some moving epitaphs on them.

Hi dellzeqq, I have only started commuting to work in the last couple of weeks 10 miles each way maybe 3 times a week, I work 12 hour shifts and use the car for the night shifts.

I joined a gym in January and have been more concentrating on running on a treadmill, my long run is currently 17 miles and I am adding a mile on to this each week.

I have a Tacx roller trainer that for the last few weeks have been doing at least 25 miles on in between my night shifts.

I am going to up my miles on the roller to 2 x 25 miles a day followed by a 5 - 10 mile treadmill run if I am not commuting that day.

Towards the end of the month, I will start getting out on the road to start doing 60 milers again, and then upping the miles the closer I get to the date.

Regarding the gears, I am not too clued up on the comparison ratios of an alfine against normal gears, but after the explanations on here then I will go with either my current set up or a 22T.

Cheers