I mostly ride on trails that require 2000 ft of climbing for every 10-12 miles ridden. I’m currently on a 32T oval. I’m almost always in the 51T cog in the back for climbs. I make most of the climbs - but my cadence is really slow on the tougher climbs. There are a few tech climb sections that I just don’t have the power to get up.

I noticed my friend is riding a 30T Oval and he’s a stronger rider than I am. He’s in the 3rd cog off the 51 most of the time.

I’m trying to decide whether I should go 28T oval or 30T oval. What do you guys think?

Bike is a Canyon Spectral CF7, 29er.

Thanks

I would start with 30t and see how you feel. Way easier to go down than back up.

I'd say just the opposite and go 28t. I've never been climbing a steep hill and thought gee I wish this were harder and even if I did I could shift to a harder gear. I do often wish I had one gear easier. I've had 28-32 and rarely ran out of topend with the 28t.

Thanks for the input.

So when I converted from 32T round to 32T oval I bot an absoluteBlack chainring. It was ~100$ shipped. I'm trying to save some money this time around, especially since I'm not sure if I should go 28T or 30T. I found a company on Amazon that sells HG+ 12 speed "compatible" single chainrings. The one caveat is you cannot use a shimano 12-speed quick link with their chainring. The shimano 12-speed quicklink is too narrow. I measured my quicklink widths : 3.45mm. The width of the links on the chain is ~3.72mm.

"If you are non-shimano brand 12 speed chain, it works for your 12s system. If your chain is shimano brand original 12 speed chain, you have to buy a Non-shimano brand 12s quick link to replace the original shimano 12s quick link."

Here's the company's product list on Amazon. Anyone have any experience? Seems like they get good reviews.

Amazon shimano compatible chainring 12 speed

I wouldn't buy random no-name junk from a known fake and knock off seller even especially more if they are saying it won't work with a common set up. That seems dangerous if the chainring cannot work with common chain and quick link combination. It isn't one I would want to have on any of my bikes.

Start with the 30t in a quality chainring from a known quantity and quality from a source that is an actual bike shop (even if just simply an online only shop) and if you find that doesn't work maybe try and record some mileage for it and re-sell it or keep it for later.

Yeah you're right - don't mess around with knock offs.

I can get an Absolute Black 28T or 30T for like $85 shipped. If I decided to go 28T would I need to remove a chain link? (In which case I'd need to get new quick links. Shimano says don't reuse).

Yeah it may save you a buck but will cost you more in the long term for little back.

If you go with a smaller ring you will probably need to resize your chain and I would get a new link. I don't really mess around with their recommendations if they say get a link I say get a link. It might be a ploy to sell more product but there is usually some truth to it.

That is why I said try the 30t first because you can always remove more links but adding them in is tougher.

So I just went thru the gear ratios for my cassette comparing a 28T vs 30T vs 32T (current).

One click down (smaller cassette cog) on a 28T ~= 32T gear ratio. It's not always exact but its pretty close. See the color coded chart. Plus I gain a whole new gear = 28-51.

Where I ride, I'm mostly in 51, and then in 45, 39 and occasionally 33, maybe 28. When I'm descending its mostly maneuvering and brake checking here and there. I'm never in the 10, 12, 14, 16. And I never ride this bike around town.

So I'm leaning toward a 28T Oval.

I'll grab some quick links as well. If I don't use it, its nice to carry in the hip pack in case there's a mishap.

Can you test ride one of your friends bikes with the smaller ring? That way you don't have to decide blindly.

FWIW, I've got a 32x10-52 setup, pretty common. For the long uphill grind, I never have an issue. There are some occasions when I want to go up some steep rock ramp or other weird obstacles and run out of power.

The tricky part is, do I need a smaller chainring, or do I actually need a bigger one and stronger legs? At those low gears, I'm barely moving. It's slow enough that I end up doing track stands on obstacles and small bumps completely stop my progress and I tip over. An even lower gear would slow me down even more, it gets closer to the minimum allowed by physics, to stay moving.

If I'm on a steep non technical trail just grinding, I can go 3-4mph which is plenty. If you want a lower gear for that, do it. You almost certainly won't notice the loss on the high gears.

I took the slowest sections (climbs) of my last ride from Strava and calculated my cadence. My cadences range from 26 - 54. That's super slow. To the point where I could be hurting my knees from grinding. And I'm pretty sure I'm in the granny (51) for most of the slower sections.

I'm fairly lean - 5'9" 150lbs. I run 3 miles at an 8:00 pace. I think my legs are just not strong enough. Can I get them stronger - sure. But its not going to happen overnight. I'm also 51 years old so I'm battling father time. The last thing I want to do is hurt my knees from grinding up hill.

You make a good point about moving too slow - to the point where I'm going to tip over. The first two sections below (same trail section) I'm moving at 1.4 - 1.9 mph. That's slow. But I'm not tipping over. Would a smaller front ring help? I think so b/c I'd be able to spin at a higher (and safer) cadence which could translate to either the same speed or potentially even faster.

See cadences below:

I've had a 28T oval ring on my MTB for the last 8 years. It's very helpful to allow for recovery during non-technical climbing, but for tech climbing I generally need to upshift a a gear or two to get enough thrust to get over obstacles. I do find that I spin out in the 28/10 top gear - most often when on pavement while heading to/from trails - but this is a small price to pay for greater climbing endurance.

Wow! How steep are these 1/2 mile climbs?


While dropping down to a 28 will help you with cadence - it probably wont do very much for speed. For more speed, you will need more power. You may get some power from higher cadence, but that will come at the cost of higher aerobic output.

28x51 at 60 rpm should be 2.8 mph. At your weight, assuming a 15% grade - you need to push about 170-175w to turn that 60rpm. 10% grade at that same power and you would get 84rpm.

I dunno if you know what your power numbers are - but the above is a rough guide of what you need.

Edit:
MTBing is flipping hard. Gearing or not! As a roadie moving into MTBing a bit - I find every ride on my MTB to be a full on FTP and VO2 max interval session wrapped up into one ride.

Got the 28T oval. Put it on. Seems like the derailleur is fine in 51. But on the smallest cog its pretty slack. See the chain sort of hanging. Once I put some pressure on the pedals the slack is taken up. One gear up from the smallest is fine - no slack in the chain.

Do I need to remove a link? FYI I will never be in that small cog. Like never.

I would say that chain is too long if you went down in chainring sizes by 4 teeth you will need to shorten your chain. That is always the case. Also use your gears, don't be afraid to shift into a smaller cog it is pretty normal to use all of them that is why they made cassettes with those ranges.

Took off a link. Chain looks much better in the small cassette cog. Thanks!!!

1. So after the ride with the "LONG" chain, I noticed the chain was rubbing against the protective foam material on my frame. And it lightly scratched the carbon.
2. Rode the next day with the "SHORT" chain. I put some electrical tape on in that area before the ride. After the ride I saw the electrical tape was split.

Maybe the 28T oval ring (Absolute Black) is too small for my frame. When the rotation is on the smaller section of chainring the chain seems to get too close to the frame. Is there anything I can do about it?

Here's a picture:

Glad it is looking better, I would reach out to the frame manufacturer and see what they suggest about the chain rubbing the frame and what their minimum chainring size is?

3m mastic tape 2228 Is a nice thick rubberish tape, works really well in areas that take a real beating.

Not sure where you mountain bike at it, but it's rare that I use the smallest 4 cogs. Maybe a sprint on a flat surface of the last 100 yards or so of race but that's about it.

I may not use it super often but I have used them why bother having them if you aren't going to use them? Certainly downhill they are more helpful but have had enough flat sections and some general singletrack near me. Also very helpful to get to the trail if you aren't taking a car.

Yeah. I take my bike to the trail by car. Once on the trail it's rare that I use the smallest 4 cogs. Trails I ride aren't flat.

I cut away a small section of the rubber protecter and replaced it with thick tape. Some frame protection tape I had in the parts bin. The chain rubbed a groove onto the tape. But didn't damage the frame.

I called the manufacturer..... they will get back to me in about 2-3 months. I asked on a Canyon specific forum and guys are saying even a 30T round will cause chain rub. Oh well....I guess back to 32T oval. And some leg extension exercises in the gym.

Anyway does the derailleur look too stretched out here? This is with the 32T oval.

Your derailleur is in about the same position mine is in in my lowest gear. Seems pretty tight but it works well.

Yikes!!!!

Do you have a long cage derailleur with a 50 or higher tooth count?

They pretty much all look like this. If the top pulley isn't rubbing, it's about right.

If he added a link or 3, it'd droop in the smallest cog.

Personally, I'd be perfectly fine with an 11 or 12 tooth smallest cog. Even for fast downhill. Seems to me the 10 tooth is ornamental except on the occasion downhill paved stretch, which these bikes don't do too often. At least it gives me a better chainline in the 12 to 17 area.

Yes. 3 different bikes. None of them look that tight.