Gear Inches & Hills

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Kieren Feb 2014 1:41am, 11 Feb 2014 3,713 posts	0 Kieren I'm after a new bike and will probably be getting a bromton on the cycle to work scheme but I am having a hard time deciding on gear ratios. Any tips most welcome. ------------------------------- This fuji above has been my bike for the last 9 years and it runs 42x16 which gives me just over 69 gear inches. I've been happy with that as I can go fast and get up reasonably steep hills quite easily. The steepest probably being an 11% gradient in Richmond Park. However that is clipped in, out of the saddle and putting power around the full pedal stroke. This is easier with no free wheel The 2nd bike will be mostly for commuting but I do like the idea of being able to take it places and maybe go for a ride. I do like the turn of speed I can get from 69 gear inches and would like to be able to zoom past the off cyclist now and then and get up steep hills. Pedals will be platform, no clips or straps and the bulk of the bikes work will be sit up and beg style commuter cycling (rather than aero / racer style).
Gobi Feb 2014 7:42am, 11 Feb 2014 53,529 posts	0 Gobi Just get a simple 3 speed sturmy archer Brompton Otherwise if you like a 69inch gear and are concerned about the flat pedals just move to either 42 x 17 or 40 x 16, bother will be easier to ride than the current 42 x 16 which means you may lose a little top end but will help you climb the hills. I ride between 94 x 105 inch gears on the track so I dread to think what you cadence is like riding a 69 inch gear, I once rode an 85inch in a race and spun my legs off :¬)
Kieren Feb 2014 9:53am, 11 Feb 2014 3,714 posts	0 Kieren Thanks Gobi. 3 speed Brompton is looking like the way to go. I think I get options on the chain ring size. Any tips there? You must zoom to be spinning out. I find at 69, cruising speed is about 22mph. Slower or faster is harder work. I span out on that downhill in Richmond park though when I first got it. I think at just under 38mph I was spinning at close to 180rpm and the back wheel started to skip when my hips tightened. Rather scary. That said, I font think I'd be able to climb that hill in a bigger gear
Gobi Feb 2014 10:16am, 11 Feb 2014 53,530 posts	0 Gobi Get the biggest front ring they do as the 3 speed lowest gear will climb alpe d'huez I spin to about 140 rpm on the track, spend a lot of time between 28 and 38 mph
Kieren Feb 2014 8:55pm, 11 Feb 2014 3,715 posts	0 Kieren Just been reading the Bromton thread. OMG Gobi & Rach !!! [IMAGE] I think I'm going to do this. So exciting! I need to get a quote on the weekend. Here's what I'm thinking: * Chainset: BSR 3 Speed (with optional upgrade +8% that gives a 54 tooth chainring and 44.3 // 59.1 // 78.8 gear inches ref: Brompton gear calc: xldev.co.uk * M handlebars. (for confort & visbility) * mudguards, no rack * tyres - no idea
Gobi Feb 2014 9:58pm, 11 Feb 2014 53,534 posts	0 Gobi Nice
Dvorak Mar 2020 10:49am, 29 Mar 2020 19,338 posts	0 Dvorak What did you get in the end, Kieran?
Kieren Apr 2020 12:41pm, 7 Apr 2020 3,903 posts	0 Kieren wow - that is some thread bump Dvorak!! I got a Brompton ML3 - standard gearing. That is the one with the flexi-U shape handlebars. The standard gears are quite tall, so I can go very fast in the middle gear and the small gear is not quite small enough to get up some big hills. In hindsight I probably would prefer a 3 speed with easier gearing (an option) and the flat bar. I got mudguards and the mount on the front for a bag. It was expensive at about £1000 all in but I do feel it is good value. The quality is excellent and they seem to be one of those products you buy once. I can't believe I was thinking of getting a harder gear option - that would have been uncomfortable. Bromptoms are quite twitchy / responsive so take a little getting used to.
Dvorak Apr 2020 4:00pm, 7 Apr 2020 19,418 posts	0 Dvorak Cheers You have had much fun with it, then? Sounds like a four-speed hub gear would be ideal in them?
Kieren Apr 2020 9:05pm, 9 Apr 2020 3,905 posts	0 Kieren Actually, for London I think the 2 speed is enough. The 3 speed is plenty with the lower gear. I think only if there are very steep / long hills might the 6 speed be worthwhile.