Which size 700c tyres for my 29er?

Londonscottish

Hi All,

Newbie here with my first question.

I run an old Rockhopper on 26 inch rims with 50mm Continental Top Contacts. Ran an old Diamond back on same rims & tyres and love that set up (London commuting and general urban stuff).

I now have a 2013 Trek Cobia 29er currently running Schwalbe Big Apple 2.15 inches which I hate (pavement suckers).

So....I want to buy a set of 700c Top Contacts for my Cobia.

I want to replicate the set up on my 26er as closely as possible with the caveat that I think the rims on the Cobia are much narrower than those on the Rockhopper (need to measure them tonight).

....given all that should I just go for the 700c 46mm (to get as close to the 50mm on my 26er) or 700c 42mm (as if I have a narrower rim they may balloon out and dropping the tyre width may give me the same depth)

Has anyone run these tyres (or equivalent) on a 29er?

Thans

The Rookie

Rule of thumb is the tyres can go to the same width as the internal rim width, no less.

Only you know what suites you, personally I'd be going to something like a 38 or 32mm to reduce the drag,

Londonscottish

The Rookie wrote:

Rule of thumb is the tyres can go to the same width as the internal rim width, no less.

Only you know what suites you, personally I'd be going to something like a 38 or 32mm to reduce the drag,

Well I tried 1.3's on my 26er and found them very harsh - they lasted one commute. I guess that'll be 32mm in new money.

So i guess it's 42 or 46 for me.

Just making sure I wasn't missing something as the 29 rims look narrow to my naked eye and I was wondering if that was going to make the tyres balloon out and become "deeper".

In which case a 42 on a narrower 29er rim might be equivalent in depth to a 50mm on a wider 26er rim.

I'll measure the rims this evening....

supersonic

29er rims are the width they are - could be owt. The average xc/trail width is the same for both wheel sizes. Of course going for a smaller tyre will reduce overall radius, but it will drop the bottom bracket height too.

photonic69

I use Continental Travel Contact in 700 x 35 on my 29er rims. Fit well and good easy rolling ride with plenty of grip.

Londonscottish

supersonic wrote:

29er rims are the width they are - could be owt. The average xc/trail width is the same for both wheel sizes. Of course going for a smaller tyre will reduce overall radius, but it will drop the bottom bracket height too.

Thanks Supersonic. I'll have a look in a minute.

Losing BB height would be no bad thing as the whole bike feels miles off the ground already. And I hardly need a ton of clearance crossing the city.

Londonscottish

PhotoNic69 wrote:

I use Continental Travel Contact in 700 x 35 on my 29er rims. Fit well and good easy rolling ride with plenty of grip.

Thanks

Londonscottish

supersonic wrote:

29er rims are the width they are - could be owt. The average xc/trail width is the same for both wheel sizes. Of course going for a smaller tyre will reduce overall radius, but it will drop the bottom bracket height too.

Had a look. Not very scientifically, the rims on the 26 and 29er are roughly the same - 23-25mm at a guess. The 29 rims look narrower as they (a) have a very different x-section and (b) are fitted with clown tyres.

Which I only fitted because I thought I had to buy "29er" tyres and the Big Apples were the only ones non-knobblies I could find at the time.

Oh well you live and learn.

photonic69

Look here for good guide for rim/tyre measurement.
http://sheldonbrown.com/rim-sizing.html

My rims are 622x19 or 19mm inner rim size. Quite standard for some 29ers I believe.

As long as the tyres have 622 in the size they 'should' fit your rims

Londonscottish

PhotoNic69 wrote:

Look here for good guide for rim/tyre measurement.
http://sheldonbrown.com/rim-sizing.html

My rims are 622x19 or 19mm inner rim size. Quite standard for some 29ers I believe.

As long as the tyres have 622 in the size they 'should' fit your rims

Thanks PN. Have ordered a set but will have a good look when they arrive to make sure they are 622' before I rip off the packaging.

Fingers crossed because if they are right I have a feeling they'll be a massive improvement over the Big Apples.

The Rookie

Londonscottish wrote:

Had a look. Not very scientifically, the rims on the 26 and 29er are roughly the same - 23-25mm at a guess.

Inner rim width is usually about 4mm less than the outer, so a 17mm internal width rim (narrowest commonly available) would be 21mm external width and so on.

The larger diameter wheels of a 29er will smooth the lumps so a narrower tyre will be as comfortable as a slightly wider on a 26er.

Londonscottish

Londonscottish wrote:

PhotoNic69 wrote:

Look here for good guide for rim/tyre measurement.
http://sheldonbrown.com/rim-sizing.html

My rims are 622x19 or 19mm inner rim size. Quite standard for some 29ers I believe.

As long as the tyres have 622 in the size they 'should' fit your rims

Thanks PN. Have ordered a set but will have a good look when they arrive to make sure they are 622' before I rip off the packaging.

Fingers crossed because if they are right I have a feeling they'll be a massive improvement over the Big Apples.

OMG. Night and day. I've only had a quick spin up the road but the bike is transformed. It's like having a new bike.

Oddly enough this whole 28/29/600c confusion is endemic. When I first bought the Cobia (in a massive rush as I'd snapped the frame on my commuter) I was concerned about tyre choice. I must have asked in three, four or maybe five different bike shops and not one person realised that they are all 622's. So I ended up wasting £35 and four months of commute life on Big Apples. Revolting things. Although good for fitness I suppose....

Londonscottish

The Rookie wrote:

Londonscottish wrote:

Had a look. Not very scientifically, the rims on the 26 and 29er are roughly the same - 23-25mm at a guess.

Inner rim width is usually about 4mm less than the outer, so a 17mm internal width rim (narrowest commonly available) would be 21mm external width and so on.

The larger diameter wheels of a 29er will smooth the lumps so a narrower tyre will be as comfortable as a slightly wider on a 26er.

Thanks Rookie. Bottled out of the 42's and went for the 47's. Loving them. My bike is now complete.

photonic69

Good tyres aren't they? Glad you got it sorted. Just don't inflate then too hard - I had them up around 100psi and they lose grip on Tarmac. It resulted in a nasty fall for me. Shouldn't have been so eager to lessen rolling resistance.

The Rookie

Londonscottish wrote:

The Rookie wrote:

Londonscottish wrote:

Had a look. Not very scientifically, the rims on the 26 and 29er are roughly the same - 23-25mm at a guess.

Inner rim width is usually about 4mm less than the outer, so a 17mm internal width rim (narrowest commonly available) would be 21mm external width and so on.

The larger diameter wheels of a 29er will smooth the lumps so a narrower tyre will be as comfortable as a slightly wider on a 26er.

Thanks Rookie. Bottled out of the 42's and went for the 47's. Loving them. My bike is now complete.

I'm sure they would have been fine, I run 1.50" on my commuter (26") which is the same as 38mm, but as long as you are happy now.

Londonscottish

PhotoNic69 wrote:

Good tyres aren't they? Glad you got it sorted. Just don't inflate then too hard - I had them up around 100psi and they lose grip on Tarmac. It resulted in a nasty fall for me. Shouldn't have been so eager to lessen rolling resistance.

Yes thet are great.

I run them at 50-55 front and 60-65 rear. I commuted for 4 years on the 26 inch version and loved them. There's still plenty of life left in them too. When I bough the Cobia immediately looked for the "29er" version with no joy without realising the 700c would fit.

No I won't over-inflate. I've been running the Big Apples 20-odd PSI too hard to counteract the natural drag and kit makes them very skittery, even in the dry.

Londonscottish

The Rookie wrote:

Londonscottish wrote:

The Rookie wrote:

Londonscottish wrote:

Had a look. Not very scientifically, the rims on the 26 and 29er are roughly the same - 23-25mm at a guess.

Inner rim width is usually about 4mm less than the outer, so a 17mm internal width rim (narrowest commonly available) would be 21mm external width and so on.

The larger diameter wheels of a 29er will smooth the lumps so a narrower tyre will be as comfortable as a slightly wider on a 26er.

Thanks Rookie. Bottled out of the 42's and went for the 47's. Loving them. My bike is now complete.

I'm sure they would have been fine, I run 1.50" on my commuter (26") which is the same as 38mm, but as long as you are happy now.

Think the rims are 18mm.

I'm sure the 38's would also have been good but having had a bad experience with 1.3inch Scwalbes I was nervous about going too narrow.

And at the price I didn't want to risk getting it wrong (again).

The Rookie

Yeah but 1.3" is just 33mm!

I tried some 1" Conti's in 26", very fast, but yes brutally harsh.

Londonscottish

The Rookie wrote:

Yeah but 1.3" is just 33mm!

I tried some 1" Conti's in 26", very fast, but yes brutally harsh.

Nipped out at lunchtime and did a five mile circuit.

To say I'm happy is an understatement.

I feel like I have a new bike.

I have finally fallen for my 29er.

What a massive massive difference the right tyres make.

The Rookie

Not to mention you've probably shed about 250g each end.

Londonscottish

The Rookie wrote:

Not to mention you've probably shed about 250g each end.

Oh yeah - hadn't thought of that.

Given the price I'd hope they are reasonably light.

However they're made/what ever they're made of they do do the job very well.

Londonscottish

Did the first commute on them today. Fast, quiet, comfortable, grippy when leaning hard.

They've made the bike shrink around me.

Only annoying things was my new-found ability to blast off at the lights was conflicting badly with the roadies setting off in top gear at snails pace doing the crick/crack/crick cleat thing. Are they on some sort of TDF fantasy or something? How hard is it to drop down three or four cogs before coming to rest? Really don't know why they do that. Grumble over.